Definition
Milk peptides are formed from milk proteins through enzymatic breakdown by digestive enzymes or by the proteinases of lactobacilli during the fermentation of milk. These peptides directly influence numerous biological processes evoking behavioral, gastrointestinal, hormonal, immunological, neurological, and nutritional responses.
Discovery
The major protein fractions in bovine milk include a-LA, ß-LG, caseins, immunoglobulins, lactoferrin, proteose- peptide fractions (heat-stable, acid soluble phosphoglycoproteins and minor whey proteins such as transferrin and serum albumin. Antimicrobial milk proteins, such as lactoferrin, were described in early literature1. Casecidin, obtained by chymosin digestion of casein at neutral pH, was among the first defense peptides actually purified and exhibited activity in vitro against Staphylococcus, Sarcina, Bacillus subtilis, Diplococcus pneumoniae, and Streptococcus pyogenes2. Milk also contains peptides that exhibit antifungal properties like lactoferrin or its peptides (ex. lactoferricin B., in combination with azole antifungal agents, has been demonstrated with Candida albicans3.
Stuctural Characteristics
Milk peptides have a high content of negative charges they will efficiently bind divalent cations with the formation of soluble complexes. Complexes of peptides and minerals of Fe, Mg, Mn, Cu and Se are reported. The high content of negative charges makes these phosphopeptides resistant to further hydrolysis. Milk caseins are easily degradable proteins due to their random coil structure. The whey proteins, b-lactoglobulin, a-lactalbumin and lactoferrin also give rise to peptides with mineral binding abilities. These proteins are regarded as more resistant to enzymatic attack and undergo hydrolysis much more slowly than the caseins4.
Mode of action
Milk peptides may affect mucosal immunity possibly by guiding local immunity until it develops its full functionality5. Several milk peptides have been shown to have antihypertensive effects in animal and in clinical studies. The most studied mechanism underlying the antihypertensive effects of milk peptides is inhibition of angiotensin-converting enzyme6. Angiotensin-converting enzyme inhibition (ACE. is an enzyme that plays a crucial role in the function of the renin-angiotensin system (RAS). The RAS is an important regulator of blood pressure and fluid and electrolyte balance. In the RAS, angiotensin I is converted to angiotensin II by ACE. Angiotensin II is a strong vasoconstrictor that induces release of aldosterone and therefore increases sodium concentration and furthers the blood pressure. ACE inhibitors have 2 effects on the renin-angiotensin system. They reduce production of angiotensin II and inhibit the degradation of the vasodilator.
Several milk peptides have opioid-like activities are derived from ??casein, called ?-exorphins, and those derived from ?-casein are called casoxins. These peptides have been shown to lower blood pressure. Because the antihypertensive effect of ?-lactorphin was completely prevented by an opioid receptor antagonist naloxone, it has been proposed that the antihypertensive effect is mediated via opioid receptors.
Functions
Antimicrobial Peptides - Milk contains a variety of components that provide immunological protection and facilitate the development of neonatal immune competence6. Lactoferrin is another milk bioactive compound with nutritional and health promoting properties; it modulates the microbial intestinal environment, displays anti-microbial activity against various pathogens and stimulates the establishment of beneficial microflora.
Antihypertensive Peptides (ACE Inhibitors) - Antihypertensive peptides inhibit the angiotensin converting enzyme (ACE), ACE converts angiotensin I to angiotensin II, increasing blood pressure and aldersterone, and inactivating the depressor action of bradykinin7.
Antithrombotic Peptides- Antithrombotic peptides are present in milk, involved in milk clotting, defined by the interaction of ?-CN with chymosin and blood clotting processes8.
Caseinophosphopeptides- Casein phosphopeptides (CPP) have been identified after trypsin release from as1-, as2-, and ß-CN. This complex formation results in an increased solubility which, in turn, provides enhanced absorption of calcium across the distal small intestines of animals fed casein diets in comparison to control animals fed soy-based diets7.
Immunomodulatory Peptides - Immunomodulatory milk peptides affect both the immune system and cell proliferation responses. ß-casokinins inhibit ACE enzymes that are responsible for inactivating bradykinin, a hormone with immune enhancing effects7.
References
1. Bullen JJ, Rogers HJ, Leigh L (1972). Iron binding proteins in milk and resistance to E. coli infections in infants. Br. Med, 1: 69–75.
2. Lahov E and W Regelson (1996) Antibacterial and immunostimulating casein-derived substances from milk: casecidin, isracidin peptides. Food Chem. Toxicol, 34: 131–145.
3. Wakabayashi H, Abe S, Okutomi T, Tansho S, Kawase K, Yamaguchi H (1996). Cooperative anti-Candida effects of lactoferrin or its peptides in combination with azole antifungal agents. Microbiol. Immunol, 40: 821–825.
4. Vegarud GE, Langsrud T, Svenning C (2000.. Mineral-binding milk proteins and peptides; occurrence, biochemical and technological characteristics. British Journal of Nutrition, 84(1): 91-98.
5. Politis I and Chronopoulou R (2007). Milk Peptides and Immune Response in the Neonate. Advances in Experimental Medicine and Biology, 606: 253-269.
Tuesday, August 25, 2009
Kassinins
Definition
Dodecapeptide tachykinin that is kassinin is found in the central nervous system of the amphibian Kassina senegalensis. It is similar in structure and action to other tachykinins, but it is especially effective in contracting smooth muscle tissue and stimulating the micturition reflex.
Discovery
In 1964, Erspamer et al., first demonstrated the occurrence of bioactive peptide, kassinin in amphibian skin1. A biosynthetic precursor of kassinin cDNA encoding the novel kassinin analog (Thr2, Ile9)-kassinin was identified in skin secretion of amphibian2. In 1983, two new mammalian tachykinins, neurokinin A and neurokinin B, were discovered in the porcine spinal cord. Their pharmacological actions more closely resemble those of the amphibian tachykinin kassinin and the molluscan tachykinin eledoisin3.
Structural Characteristics
Tachykinins are among the most widely-studied families of regulatory peptides characterized by a highly-conserved C-terminal -Phe-X-Gly-Leu-Met amide motif, which also constitutes the essential bioactive core. Both the aqueous and lipid-induced structure of kassinin, has been studied by Rani et al., (2001). Water kassinin prefers to be in an extended chain conformation, in the presence of perdeuterated dodecylphosphocholine (DPC) micelles, a membrane model system, helical conformation is induced in the central core and C-terminal region (K4-M12) of the peptide. N-terminus though less defined also displays some degree of order and a possible turn structure. The conformation adopted by kassinin in the presence of DPC micelles is consistent with the structural motif typical of neurokinin-1 selective agonists and with that reported for eledoisin in hydrophobic environment4.
Mode of Action
In frog skin, tachykinins stimulate the ion transport, by interacting with NK1-like receptors which can be estimated by measuring the short-circuit current (SCC) value. Kassinin (NK2 preferring in mammals) increases the SCC5. Kassinin also induces concentration-related contractions of the longitudinal muscle of the mouse distal colon. Contractile responses to the tachykinins result from a direct activation of smooth muscle cells. Kassinin evokes a contractile response in the absence of external Ca2+ and their myogenic activity was, to some extent, resistant to the inhibitory effect of nifedipine (a calcium channel blocker). So an additional process, probably the release of an intracellularly bound Ca2+ store, participates in the mechanism by which kassinin contracts the mouse distal colon. After desensitization of the mouse distal colon to Substance P (SP), the contractile activity provoked by SP was totally abolished whilst the responses evoked by kassinin were barely affected. These observations and other experimental findings indirectly support the assumption that the mouse distal colons possess different tachykinin-binding sites6.
Functions
Effect on rat urinary bladder - Synthetic replicates of kassinin are found to be active on rat urinary bladder smooth muscle at nanomolar concentrations2. Kassinin induces concentration-related contractions of the longitudinal muscle of the mouse distal colon.
Effect on endocrine pancreatic function - The effect of kassinin on endocrine pancreatic function was examined in the rat. Kassinin, injected intravenously in graded doses 10, 20, and 30 min before blood collection, significantly increased both plasma insulin and plasma glucagon in a dose-related fashion. The largest dose examined (10 µg) increased plasma insulin by 275% and plasma glucagon by 77% 7.
Synthetic kassinin affects splanchnic circulation - Effects of intravenously administered synthetic kassinin on splanchnic circulation and exocrine pancreatic secretion was examined in six anesthetized dogs. Kassinin caused dose-related increases in the blood flow in superior mesenteric artery and portal vein, and produced an initial increase followed by a decrease in pancreatic blood flow, but did not affect the exocrine pancreatic secretion. This study suggests that kassinin functions as a neuropeptide controlling the splanchnic circulation in mammalian species8.
References
1.Book : Handbook of chemical neuroanatomy. Chapter VI Neurokinin receptors in the CNS by Da-silva R, Mcleod AL, Krause JE.
2.Wang L, Zhou M, Lynch L, Chen T, Walker B, Shaw C (2009). Kassina senegalensis skin tachykinins: Molecular cloning of kassinin and (Thr2, Ile9)-kassinin biosynthetic precursor cDNAs and comparative bioactivity of mature tachykinins on the smooth muscle of rat urinary bladder. Biochimie, 91(5): 613-619.
3.Tan DP and Tsou K (1988). Differential Effects of Tachykinins Injected Intranigrally on Striatal Dopamine Metabolism. Journal of Neurochemistr, 51(5): 1333-1337.
4.Rani CR, Lynn AM, Cowsik SM (2001). Lipid Induced Conformation of the Tachykinin Peptide Kassinin. Journal of Biomolecular Structure and Dynamics, 18 (4): 611-625.
5.Lippe C, Bellantuon V, Ardizzone C, Cassano G (2004). Eledoisin and Kassinin, but not Enterokassinin, stimulate ion transport in frog skin. Peptides, 25(11): 1971-1975.
6.Fontaine J and Lebrun P (1989). Contractile effects of substance P and other tachykinins on the mouse isolated distal colon. Br J Pharmacol, 96(3): 583–590.
7.Gullner HG, Yajimsa H, Harris V, Unger RH (1982). Kassinin: Stimulation of Insulin and Glucagon Secretion in the Rat. Endocrinology, 110 (4): 1246-1248.
8.Doi R, Inoue K, Kogire M, Sumi S, Takaori K, Yun M, Yajima H, Tobe T (1988). Effects of synthetic kassinin on splanchnic circulation and exocrine pancreas in dogs. Peptides, 9(5): 1055-1058.
Dodecapeptide tachykinin that is kassinin is found in the central nervous system of the amphibian Kassina senegalensis. It is similar in structure and action to other tachykinins, but it is especially effective in contracting smooth muscle tissue and stimulating the micturition reflex.
Discovery
In 1964, Erspamer et al., first demonstrated the occurrence of bioactive peptide, kassinin in amphibian skin1. A biosynthetic precursor of kassinin cDNA encoding the novel kassinin analog (Thr2, Ile9)-kassinin was identified in skin secretion of amphibian2. In 1983, two new mammalian tachykinins, neurokinin A and neurokinin B, were discovered in the porcine spinal cord. Their pharmacological actions more closely resemble those of the amphibian tachykinin kassinin and the molluscan tachykinin eledoisin3.
Structural Characteristics
Tachykinins are among the most widely-studied families of regulatory peptides characterized by a highly-conserved C-terminal -Phe-X-Gly-Leu-Met amide motif, which also constitutes the essential bioactive core. Both the aqueous and lipid-induced structure of kassinin, has been studied by Rani et al., (2001). Water kassinin prefers to be in an extended chain conformation, in the presence of perdeuterated dodecylphosphocholine (DPC) micelles, a membrane model system, helical conformation is induced in the central core and C-terminal region (K4-M12) of the peptide. N-terminus though less defined also displays some degree of order and a possible turn structure. The conformation adopted by kassinin in the presence of DPC micelles is consistent with the structural motif typical of neurokinin-1 selective agonists and with that reported for eledoisin in hydrophobic environment4.
Mode of Action
In frog skin, tachykinins stimulate the ion transport, by interacting with NK1-like receptors which can be estimated by measuring the short-circuit current (SCC) value. Kassinin (NK2 preferring in mammals) increases the SCC5. Kassinin also induces concentration-related contractions of the longitudinal muscle of the mouse distal colon. Contractile responses to the tachykinins result from a direct activation of smooth muscle cells. Kassinin evokes a contractile response in the absence of external Ca2+ and their myogenic activity was, to some extent, resistant to the inhibitory effect of nifedipine (a calcium channel blocker). So an additional process, probably the release of an intracellularly bound Ca2+ store, participates in the mechanism by which kassinin contracts the mouse distal colon. After desensitization of the mouse distal colon to Substance P (SP), the contractile activity provoked by SP was totally abolished whilst the responses evoked by kassinin were barely affected. These observations and other experimental findings indirectly support the assumption that the mouse distal colons possess different tachykinin-binding sites6.
Functions
Effect on rat urinary bladder - Synthetic replicates of kassinin are found to be active on rat urinary bladder smooth muscle at nanomolar concentrations2. Kassinin induces concentration-related contractions of the longitudinal muscle of the mouse distal colon.
Effect on endocrine pancreatic function - The effect of kassinin on endocrine pancreatic function was examined in the rat. Kassinin, injected intravenously in graded doses 10, 20, and 30 min before blood collection, significantly increased both plasma insulin and plasma glucagon in a dose-related fashion. The largest dose examined (10 µg) increased plasma insulin by 275% and plasma glucagon by 77% 7.
Synthetic kassinin affects splanchnic circulation - Effects of intravenously administered synthetic kassinin on splanchnic circulation and exocrine pancreatic secretion was examined in six anesthetized dogs. Kassinin caused dose-related increases in the blood flow in superior mesenteric artery and portal vein, and produced an initial increase followed by a decrease in pancreatic blood flow, but did not affect the exocrine pancreatic secretion. This study suggests that kassinin functions as a neuropeptide controlling the splanchnic circulation in mammalian species8.
References
1.Book : Handbook of chemical neuroanatomy. Chapter VI Neurokinin receptors in the CNS by Da-silva R, Mcleod AL, Krause JE.
2.Wang L, Zhou M, Lynch L, Chen T, Walker B, Shaw C (2009). Kassina senegalensis skin tachykinins: Molecular cloning of kassinin and (Thr2, Ile9)-kassinin biosynthetic precursor cDNAs and comparative bioactivity of mature tachykinins on the smooth muscle of rat urinary bladder. Biochimie, 91(5): 613-619.
3.Tan DP and Tsou K (1988). Differential Effects of Tachykinins Injected Intranigrally on Striatal Dopamine Metabolism. Journal of Neurochemistr, 51(5): 1333-1337.
4.Rani CR, Lynn AM, Cowsik SM (2001). Lipid Induced Conformation of the Tachykinin Peptide Kassinin. Journal of Biomolecular Structure and Dynamics, 18 (4): 611-625.
5.Lippe C, Bellantuon V, Ardizzone C, Cassano G (2004). Eledoisin and Kassinin, but not Enterokassinin, stimulate ion transport in frog skin. Peptides, 25(11): 1971-1975.
6.Fontaine J and Lebrun P (1989). Contractile effects of substance P and other tachykinins on the mouse isolated distal colon. Br J Pharmacol, 96(3): 583–590.
7.Gullner HG, Yajimsa H, Harris V, Unger RH (1982). Kassinin: Stimulation of Insulin and Glucagon Secretion in the Rat. Endocrinology, 110 (4): 1246-1248.
8.Doi R, Inoue K, Kogire M, Sumi S, Takaori K, Yun M, Yajima H, Tobe T (1988). Effects of synthetic kassinin on splanchnic circulation and exocrine pancreas in dogs. Peptides, 9(5): 1055-1058.
Kassinins
Definition
Dodecapeptide tachykinin that is kassinin is found in the central nervous system of the amphibian Kassina senegalensis. It is similar in structure and action to other tachykinins, but it is especially effective in contracting smooth muscle tissue and stimulating the micturition reflex.
Discovery
In 1964, Erspamer et al., first demonstrated the occurrence of bioactive peptide, kassinin in amphibian skin1. A biosynthetic precursor of kassinin cDNA encoding the novel kassinin analog (Thr2, Ile9)-kassinin was identified in skin secretion of amphibian2. In 1983, two new mammalian tachykinins, neurokinin A and neurokinin B, were discovered in the porcine spinal cord. Their pharmacological actions more closely resemble those of the amphibian tachykinin kassinin and the molluscan tachykinin eledoisin3.
Structural Characteristics
Tachykinins are among the most widely-studied families of regulatory peptides characterized by a highly-conserved C-terminal -Phe-X-Gly-Leu-Met amide motif, which also constitutes the essential bioactive core. Both the aqueous and lipid-induced structure of kassinin, has been studied by Rani et al., (2001). Water kassinin prefers to be in an extended chain conformation, in the presence of perdeuterated dodecylphosphocholine (DPC) micelles, a membrane model system, helical conformation is induced in the central core and C-terminal region (K4-M12) of the peptide. N-terminus though less defined also displays some degree of order and a possible turn structure. The conformation adopted by kassinin in the presence of DPC micelles is consistent with the structural motif typical of neurokinin-1 selective agonists and with that reported for eledoisin in hydrophobic environment4.
Mode of Action
In frog skin, tachykinins stimulate the ion transport, by interacting with NK1-like receptors which can be estimated by measuring the short-circuit current (SCC) value. Kassinin (NK2 preferring in mammals) increases the SCC5. Kassinin also induces concentration-related contractions of the longitudinal muscle of the mouse distal colon. Contractile responses to the tachykinins result from a direct activation of smooth muscle cells. Kassinin evokes a contractile response in the absence of external Ca2+ and their myogenic activity was, to some extent, resistant to the inhibitory effect of nifedipine (a calcium channel blocker). So an additional process, probably the release of an intracellularly bound Ca2+ store, participates in the mechanism by which kassinin contracts the mouse distal colon. After desensitization of the mouse distal colon to Substance P (SP), the contractile activity provoked by SP was totally abolished whilst the responses evoked by kassinin were barely affected. These observations and other experimental findings indirectly support the assumption that the mouse distal colons possess different tachykinin-binding sites6.
Functions
Effect on rat urinary bladder - Synthetic replicates of kassinin are found to be active on rat urinary bladder smooth muscle at nanomolar concentrations2. Kassinin induces concentration-related contractions of the longitudinal muscle of the mouse distal colon.
Effect on endocrine pancreatic function - The effect of kassinin on endocrine pancreatic function was examined in the rat. Kassinin, injected intravenously in graded doses 10, 20, and 30 min before blood collection, significantly increased both plasma insulin and plasma glucagon in a dose-related fashion. The largest dose examined (10 µg) increased plasma insulin by 275% and plasma glucagon by 77% 7.
Synthetic kassinin affects splanchnic circulation - Effects of intravenously administered synthetic kassinin on splanchnic circulation and exocrine pancreatic secretion was examined in six anesthetized dogs. Kassinin caused dose-related increases in the blood flow in superior mesenteric artery and portal vein, and produced an initial increase followed by a decrease in pancreatic blood flow, but did not affect the exocrine pancreatic secretion. This study suggests that kassinin functions as a neuropeptide controlling the splanchnic circulation in mammalian species8.
References
1.Book : Handbook of chemical neuroanatomy. Chapter VI Neurokinin receptors in the CNS by Da-silva R, Mcleod AL, Krause JE.
2.Wang L, Zhou M, Lynch L, Chen T, Walker B, Shaw C (2009). Kassina senegalensis skin tachykinins: Molecular cloning of kassinin and (Thr2, Ile9)-kassinin biosynthetic precursor cDNAs and comparative bioactivity of mature tachykinins on the smooth muscle of rat urinary bladder. Biochimie, 91(5): 613-619.
3.Tan DP and Tsou K (1988). Differential Effects of Tachykinins Injected Intranigrally on Striatal Dopamine Metabolism. Journal of Neurochemistr, 51(5): 1333-1337.
4.Rani CR, Lynn AM, Cowsik SM (2001). Lipid Induced Conformation of the Tachykinin Peptide Kassinin. Journal of Biomolecular Structure and Dynamics, 18 (4): 611-625.
5.Lippe C, Bellantuon V, Ardizzone C, Cassano G (2004). Eledoisin and Kassinin, but not Enterokassinin, stimulate ion transport in frog skin. Peptides, 25(11): 1971-1975.
6.Fontaine J and Lebrun P (1989). Contractile effects of substance P and other tachykinins on the mouse isolated distal colon. Br J Pharmacol, 96(3): 583–590.
7.Gullner HG, Yajimsa H, Harris V, Unger RH (1982). Kassinin: Stimulation of Insulin and Glucagon Secretion in the Rat. Endocrinology, 110 (4): 1246-1248.
8.Doi R, Inoue K, Kogire M, Sumi S, Takaori K, Yun M, Yajima H, Tobe T (1988). Effects of synthetic kassinin on splanchnic circulation and exocrine pancreas in dogs. Peptides, 9(5): 1055-1058.
Dodecapeptide tachykinin that is kassinin is found in the central nervous system of the amphibian Kassina senegalensis. It is similar in structure and action to other tachykinins, but it is especially effective in contracting smooth muscle tissue and stimulating the micturition reflex.
Discovery
In 1964, Erspamer et al., first demonstrated the occurrence of bioactive peptide, kassinin in amphibian skin1. A biosynthetic precursor of kassinin cDNA encoding the novel kassinin analog (Thr2, Ile9)-kassinin was identified in skin secretion of amphibian2. In 1983, two new mammalian tachykinins, neurokinin A and neurokinin B, were discovered in the porcine spinal cord. Their pharmacological actions more closely resemble those of the amphibian tachykinin kassinin and the molluscan tachykinin eledoisin3.
Structural Characteristics
Tachykinins are among the most widely-studied families of regulatory peptides characterized by a highly-conserved C-terminal -Phe-X-Gly-Leu-Met amide motif, which also constitutes the essential bioactive core. Both the aqueous and lipid-induced structure of kassinin, has been studied by Rani et al., (2001). Water kassinin prefers to be in an extended chain conformation, in the presence of perdeuterated dodecylphosphocholine (DPC) micelles, a membrane model system, helical conformation is induced in the central core and C-terminal region (K4-M12) of the peptide. N-terminus though less defined also displays some degree of order and a possible turn structure. The conformation adopted by kassinin in the presence of DPC micelles is consistent with the structural motif typical of neurokinin-1 selective agonists and with that reported for eledoisin in hydrophobic environment4.
Mode of Action
In frog skin, tachykinins stimulate the ion transport, by interacting with NK1-like receptors which can be estimated by measuring the short-circuit current (SCC) value. Kassinin (NK2 preferring in mammals) increases the SCC5. Kassinin also induces concentration-related contractions of the longitudinal muscle of the mouse distal colon. Contractile responses to the tachykinins result from a direct activation of smooth muscle cells. Kassinin evokes a contractile response in the absence of external Ca2+ and their myogenic activity was, to some extent, resistant to the inhibitory effect of nifedipine (a calcium channel blocker). So an additional process, probably the release of an intracellularly bound Ca2+ store, participates in the mechanism by which kassinin contracts the mouse distal colon. After desensitization of the mouse distal colon to Substance P (SP), the contractile activity provoked by SP was totally abolished whilst the responses evoked by kassinin were barely affected. These observations and other experimental findings indirectly support the assumption that the mouse distal colons possess different tachykinin-binding sites6.
Functions
Effect on rat urinary bladder - Synthetic replicates of kassinin are found to be active on rat urinary bladder smooth muscle at nanomolar concentrations2. Kassinin induces concentration-related contractions of the longitudinal muscle of the mouse distal colon.
Effect on endocrine pancreatic function - The effect of kassinin on endocrine pancreatic function was examined in the rat. Kassinin, injected intravenously in graded doses 10, 20, and 30 min before blood collection, significantly increased both plasma insulin and plasma glucagon in a dose-related fashion. The largest dose examined (10 µg) increased plasma insulin by 275% and plasma glucagon by 77% 7.
Synthetic kassinin affects splanchnic circulation - Effects of intravenously administered synthetic kassinin on splanchnic circulation and exocrine pancreatic secretion was examined in six anesthetized dogs. Kassinin caused dose-related increases in the blood flow in superior mesenteric artery and portal vein, and produced an initial increase followed by a decrease in pancreatic blood flow, but did not affect the exocrine pancreatic secretion. This study suggests that kassinin functions as a neuropeptide controlling the splanchnic circulation in mammalian species8.
References
1.Book : Handbook of chemical neuroanatomy. Chapter VI Neurokinin receptors in the CNS by Da-silva R, Mcleod AL, Krause JE.
2.Wang L, Zhou M, Lynch L, Chen T, Walker B, Shaw C (2009). Kassina senegalensis skin tachykinins: Molecular cloning of kassinin and (Thr2, Ile9)-kassinin biosynthetic precursor cDNAs and comparative bioactivity of mature tachykinins on the smooth muscle of rat urinary bladder. Biochimie, 91(5): 613-619.
3.Tan DP and Tsou K (1988). Differential Effects of Tachykinins Injected Intranigrally on Striatal Dopamine Metabolism. Journal of Neurochemistr, 51(5): 1333-1337.
4.Rani CR, Lynn AM, Cowsik SM (2001). Lipid Induced Conformation of the Tachykinin Peptide Kassinin. Journal of Biomolecular Structure and Dynamics, 18 (4): 611-625.
5.Lippe C, Bellantuon V, Ardizzone C, Cassano G (2004). Eledoisin and Kassinin, but not Enterokassinin, stimulate ion transport in frog skin. Peptides, 25(11): 1971-1975.
6.Fontaine J and Lebrun P (1989). Contractile effects of substance P and other tachykinins on the mouse isolated distal colon. Br J Pharmacol, 96(3): 583–590.
7.Gullner HG, Yajimsa H, Harris V, Unger RH (1982). Kassinin: Stimulation of Insulin and Glucagon Secretion in the Rat. Endocrinology, 110 (4): 1246-1248.
8.Doi R, Inoue K, Kogire M, Sumi S, Takaori K, Yun M, Yajima H, Tobe T (1988). Effects of synthetic kassinin on splanchnic circulation and exocrine pancreas in dogs. Peptides, 9(5): 1055-1058.
Interleukins, Fragments and Related Peptides
Definition
The polypeptide hormone interleukin-1 (IL-1) is one of the key mediators of host's response to microbial invasion, inflammation, tissue injury, or immunological reactions. IL-1 is a prominent member of a group of polypeptide mediators now called cytokines.
Related Peptides
The IL-1 gene family is composed of IL-1a, IL-1b, and IL-1Ra. Each member is first synthesized as a precursor protein; the precursors for IL-1 (prolL-1a and prolL-1b) each have a molecular mass of 31 kDa. The prolL-1a and mature 17 kDa lL-1a are both biologically active. In contrast, prolL-1b is relatively inactive and requires cleavage to a 17-kDa peptide for optimal biological activity. The IL-1Ra precursor has a leader sequence, is cleaved to its mature form, and is secreted like most proteins1.
Structural Characteristics
IL-1 ligands (IL-1a and IL-1b, collectively referred to as IL-1) are pluripotent, proinflammatory cytokines. These two IL l’s share only small stretches of amino acid homology (26% in the case of human IL 1). Each IL 1 is coded by a separate gene, both genes are located on chromosome 2, and each gene contains seven exons. mRNA coding for IL-1b predominates over that coding for IL-1a and this prevalence of IL-1b has been observed in the proportion of the two IL 1 forms measured in the circulation and other body fluids. Both forms of IL 1 are unique in that they are initially translated as precursor polypeptides (31,000 kDa), and despite the fact that IL 1 is found in the extracellular compartment, neither form contains a signal cleavage sequence. The generation of the NH2 terminus of the mature peptide (17,500 kDa) and smaller peptides occurs by the action of senine proteases. Of particular interest is the a/b homologous region termed C-D, which is coded entirely by the sixth exon. It has been suggest that this region may contain the minimal recognition site for IL 1 receptors. Receptors for IL 1 equally recognize the b and a forms, both forms possess the same spectrum of biological properties, and molecular modeling studies reveal that the two IL l’s are composed of b - folded sheets2,3.
Mode of Action
IL 1 specifically binds to a variety of cells. Studies with T lymphocytes and fibroblasts suggest the existence of a single class of high-affinity receptor with a dissociation constant (KD) that varies from 5 to 50 pM with 100-4000 binding sites per cell. The high-affinity receptors are rapidly internalized and bind to nuclear structures, and responsiveness to IL 1 is down-regulated. The rapid down-regulation of IL 1 receptor is specific and may account, in part, for modulating IL1 effects in several cells4. In cells stimulated with IL1, cytosolic calcium increases, sodium/potassium ion fluxes occur, and protein kinase activity increases4.
Functions
Interleukin-1: Regulator of Neuroinflammation - Interleukins 1a and 1b (IL-1) are very potent signaling molecules that are expressed normally at low levels, but are induced rapidly in response to local or peripheral insults. IL-1 coordinates systemic host defense responses to pathogens and to injury within the central nervous system (CNS). Numerous reports have correlated the presence of IL-1 in the injured or diseased brain, and its effects on neurons and nonneuronal cells in the CNS, it has been recently shown that the importance of IL-1 signaling. Further it has been demonstrate that IL-1 is at or near the top of the hierarchical cytokine signaling cascade in the CNS that results in the activation of endogenous microglia and vascular endothelial cells to recruit peripheral leukocytes (i.e., neuroinflammation). The IL-1 system thus provides an attractive target for therapeutic intervention to ameliorate the destructive consequences of neuroinflammation5.
Role of interleukin-1 in stress responses - Stress responses have been characterized as central neurohormonal changes, as well as behavioral and physiological changes. Administration of IL-1 has been shown to induce effects comparable to stress-induced changes. IL-1 acts on the brain, especially the hypothalamus, to enhance release of monoamines, such as norepinephrine, dopamine, and serotonin, as well as secretion of corticotropin-releasing hormone (CRH). IL-1-induced activation of the hypothalamo-pituitary-adrenal (HPA) axis in vivo depends on secretion of CRH, an intact pituitary, and the ventral noradrenergic bundle that innervates the CRH-containing neurons in the paraventricular nucleus of the hypothalamus. Recent studies have shown that IL-1 is present within neurons in the brain, suggesting that IL-1 functions in neuronal transmission. It has been shown that IL-1 in the brain is involved in the stress response, and that stress-induced activation of monoamine release and the HPA axis were inhibited by IL-1 receptor antagonist (IL-1Ra) administration directly into the rat hypothalamus. IL-1Ra has been known to exert a blocking effect on IL-1 by competitively inhibiting the binding of IL-1 to IL-1 receptors6.
References
1.Dinarello CA (1994). The interleukin-1 family. 10 years of discovery. FASEBJ, 8(15):1314-25.
2.Auron PE, Warner SJ, Webb AC, Cannon JG, Bernheim HA, McAdam KJ, Rosenwasser LJ, LoPreste G, Mucci SF, Dinarello CA (1987). Studies on the molecular nature of human interleukin-1. J. Immunol, 138(5):1447-1456.
3.Dinarello C A (1988). Biology of interleukin 1. FASEBJ, 2: 108-115.
4.Mizel S B, Kilian P L, Lewis J C, Paganelli KA, Chizzonite RA (1987). The interleukin 1 receptor. Dynamics of interleukin 1 binding and internalization in T cells and fibroblasts. J. Immunol., 138: 2906-2912.
5.Basu A, Krady JK, Levison SW(2004). Interleukin-1: A Master Regulator of Neuroinflammation. Journal of Neuroscience Research, 78:151–156.
6.Shintani F, Nakaki T, Kanba S, Kato R, Asai M(1995). Role of interleukin-1 in stress responses - A putative neurotransmitter. Molecular Neurobiology, 10: 47-71.
The polypeptide hormone interleukin-1 (IL-1) is one of the key mediators of host's response to microbial invasion, inflammation, tissue injury, or immunological reactions. IL-1 is a prominent member of a group of polypeptide mediators now called cytokines.
Related Peptides
The IL-1 gene family is composed of IL-1a, IL-1b, and IL-1Ra. Each member is first synthesized as a precursor protein; the precursors for IL-1 (prolL-1a and prolL-1b) each have a molecular mass of 31 kDa. The prolL-1a and mature 17 kDa lL-1a are both biologically active. In contrast, prolL-1b is relatively inactive and requires cleavage to a 17-kDa peptide for optimal biological activity. The IL-1Ra precursor has a leader sequence, is cleaved to its mature form, and is secreted like most proteins1.
Structural Characteristics
IL-1 ligands (IL-1a and IL-1b, collectively referred to as IL-1) are pluripotent, proinflammatory cytokines. These two IL l’s share only small stretches of amino acid homology (26% in the case of human IL 1). Each IL 1 is coded by a separate gene, both genes are located on chromosome 2, and each gene contains seven exons. mRNA coding for IL-1b predominates over that coding for IL-1a and this prevalence of IL-1b has been observed in the proportion of the two IL 1 forms measured in the circulation and other body fluids. Both forms of IL 1 are unique in that they are initially translated as precursor polypeptides (31,000 kDa), and despite the fact that IL 1 is found in the extracellular compartment, neither form contains a signal cleavage sequence. The generation of the NH2 terminus of the mature peptide (17,500 kDa) and smaller peptides occurs by the action of senine proteases. Of particular interest is the a/b homologous region termed C-D, which is coded entirely by the sixth exon. It has been suggest that this region may contain the minimal recognition site for IL 1 receptors. Receptors for IL 1 equally recognize the b and a forms, both forms possess the same spectrum of biological properties, and molecular modeling studies reveal that the two IL l’s are composed of b - folded sheets2,3.
Mode of Action
IL 1 specifically binds to a variety of cells. Studies with T lymphocytes and fibroblasts suggest the existence of a single class of high-affinity receptor with a dissociation constant (KD) that varies from 5 to 50 pM with 100-4000 binding sites per cell. The high-affinity receptors are rapidly internalized and bind to nuclear structures, and responsiveness to IL 1 is down-regulated. The rapid down-regulation of IL 1 receptor is specific and may account, in part, for modulating IL1 effects in several cells4. In cells stimulated with IL1, cytosolic calcium increases, sodium/potassium ion fluxes occur, and protein kinase activity increases4.
Functions
Interleukin-1: Regulator of Neuroinflammation - Interleukins 1a and 1b (IL-1) are very potent signaling molecules that are expressed normally at low levels, but are induced rapidly in response to local or peripheral insults. IL-1 coordinates systemic host defense responses to pathogens and to injury within the central nervous system (CNS). Numerous reports have correlated the presence of IL-1 in the injured or diseased brain, and its effects on neurons and nonneuronal cells in the CNS, it has been recently shown that the importance of IL-1 signaling. Further it has been demonstrate that IL-1 is at or near the top of the hierarchical cytokine signaling cascade in the CNS that results in the activation of endogenous microglia and vascular endothelial cells to recruit peripheral leukocytes (i.e., neuroinflammation). The IL-1 system thus provides an attractive target for therapeutic intervention to ameliorate the destructive consequences of neuroinflammation5.
Role of interleukin-1 in stress responses - Stress responses have been characterized as central neurohormonal changes, as well as behavioral and physiological changes. Administration of IL-1 has been shown to induce effects comparable to stress-induced changes. IL-1 acts on the brain, especially the hypothalamus, to enhance release of monoamines, such as norepinephrine, dopamine, and serotonin, as well as secretion of corticotropin-releasing hormone (CRH). IL-1-induced activation of the hypothalamo-pituitary-adrenal (HPA) axis in vivo depends on secretion of CRH, an intact pituitary, and the ventral noradrenergic bundle that innervates the CRH-containing neurons in the paraventricular nucleus of the hypothalamus. Recent studies have shown that IL-1 is present within neurons in the brain, suggesting that IL-1 functions in neuronal transmission. It has been shown that IL-1 in the brain is involved in the stress response, and that stress-induced activation of monoamine release and the HPA axis were inhibited by IL-1 receptor antagonist (IL-1Ra) administration directly into the rat hypothalamus. IL-1Ra has been known to exert a blocking effect on IL-1 by competitively inhibiting the binding of IL-1 to IL-1 receptors6.
References
1.Dinarello CA (1994). The interleukin-1 family. 10 years of discovery. FASEBJ, 8(15):1314-25.
2.Auron PE, Warner SJ, Webb AC, Cannon JG, Bernheim HA, McAdam KJ, Rosenwasser LJ, LoPreste G, Mucci SF, Dinarello CA (1987). Studies on the molecular nature of human interleukin-1. J. Immunol, 138(5):1447-1456.
3.Dinarello C A (1988). Biology of interleukin 1. FASEBJ, 2: 108-115.
4.Mizel S B, Kilian P L, Lewis J C, Paganelli KA, Chizzonite RA (1987). The interleukin 1 receptor. Dynamics of interleukin 1 binding and internalization in T cells and fibroblasts. J. Immunol., 138: 2906-2912.
5.Basu A, Krady JK, Levison SW(2004). Interleukin-1: A Master Regulator of Neuroinflammation. Journal of Neuroscience Research, 78:151–156.
6.Shintani F, Nakaki T, Kanba S, Kato R, Asai M(1995). Role of interleukin-1 in stress responses - A putative neurotransmitter. Molecular Neurobiology, 10: 47-71.
Insulin-Like Growth Factors (IGF), Fragments and Related Peptides
Definition
Insulin-like growth factors (IGF)-1 and IGF-2 are ubiquitously expressed peptides with sequence homology to insulin.
Related Peptides
IGFs interacts with a specific receptor on the cell membrane, namely, the IGF-I receptor (IGF-IR), and the interaction is regulated by a group of specific binding proteins. All of these molecules are considered to be members of the IGF family, which includes the polypeptide ligands IGF-I and IGF-II, two types of cell membrane receptors (i.e., IGF-IR and IGF-IIR), and six IGF-binding proteins (i.e., IGFBP-1 through IGFBP-6).
Structural Characteristics
IGFs
IGF-I and IGF-II are single-chain polypeptides. The two molecules have 62% homology in their amino acid sequences. The molecules share additional structural similarities, and their structures resemble the structure of proinsulin1. IGF I consists of 70 amino acid residues, IGF I1 of 67, grouped into domains A and B (similar to insulin), C (analogous to the connecting peptide of proinsulin) and D (not present in insulins). The three intrachain disulfide bridges in IGF 1 and I1 have shown to be located in analogous positions to those in (pro) insulin1.
IGFBPs
The primary structures of mammalian IGFBPs appear to contain three distinct domains of roughly equivalent sizes: the conserved N-terminal domain, the highly variable midregion, and the conserved C-terminal domain.N-terminal domain contains 80–93 amino acid residues after the signal. Ten to 12 of the 16–20 cysteines found in the prepeptides are located within this domain. In IGFBP-1 to -5, these 12 cysteines are fully conserved, whereas in IGFBP-6, 10 of the 12 cysteines are invariant2.Midregion ranging in size from 55 amino acid residues to 95 amino acids separates the N-terminal domain from the C-terminal domain. The amino acid sequence for each midsegment appears to be unique to the protein. C-terminal region are highly conserved and, 6 cysteines of the total 16–20 cysteines are found in the C terminus and are strictly conserved2.
IGF Receptors
Both IGF-IR and IGF-IIR are glycoproteins and are located on the cell membrane. IGF-IR is a tetramer of two identical a-subunits and two identical ß-subunits. Structurally, IGF-IR resembles the insulin receptor, and there is 60% homology between them. IGF-IIR is monomeric. Three ligand-binding regions are found in the extracellular domain of the receptor, one for IGF-II binding and two for proteins containing mannose-6-phosphate (M6P), including renin, proliferin, thyroglobulin, and the latent form of (TGF)-ß transforming growth factor2.
Mode of Action
Binding of IGFs to IGF-IR activates the receptor's tyrosine kinase activity, which triggers a cascade of reactions. Two distinct signal transduction pathways have been identified for IGF-IR. One pathway activates Ras protein, Raf protein, and mitogen-activated protein kinase, and the other pathway involves phosphoinositol-3-kinase. IGF-IR is involved in cell transformation. In vitro experiments have shown that removal of IGF-IR from the cell membrane by eliminating the IGF-IR gene, by suppressing its expression, or by inhibiting its function can abolish cell transformation3. IGFBPs have multiple and complex functions. IGFBPs are able to inhibit or to enhance the action of IGFs, resulting in either suppression or stimulation of cell proliferation. These opposing effects of IGFBPs on IGFs are determined by the molecular structures of the binding proteins. When binding to IGFs, IGFBPs play three major roles: 1) transporting IGFs, 2) protecting IGFs from degradation, and 3) regulating the interaction between IGFs and IGF-IR. Normally, IGFBPs have higher binding affinity to IGFs than does IGF-IR; therefore, binding of IGFBPs to IGFs blocks the interaction between IGFs and IGF-IR and suppresses IGF action. However, binding of IGFBPs to IGFs also protects IGFs from proteolytic degradation, and that protection can enhance the action of IGFs by increasing their bioavailability in local tissue3.
Functions
Direct Involvement in Cancer - IGF-I and IGF-II are strong mitogens for a wide variety of cancer cell lines. Animal experiments indicate that overexpression of IGF-I increase the likelihood of tumor development in certain tissues. The effects of IGFs on cancer cells are mediated through IGF-IR. Eliminating IGF-IR from the cell membrane, blocking the interaction of IGFs with IGF-IR, or interrupting the signal transduction pathway of IGF-IR can abolish the mitogenic action of IGFs on cancer cells. IGF-IR is overexpressed in certain cancers, and its overexpression is associated with aggressive tumors. A recent study indicates that the insulin receptor is involved in mediating the actions of IGF-II on breast cancer. Cancer cells with a strong tendency to metastasize have higher expression of IGF-II and IGF-IR than those with a low ability to do so.In cancer, IGFBPs regulate the action of IGFs. In most situations, the binding proteins suppress the mitogenic action of IGFs and promote apoptosis. It has been shown that IGFBP-3 inhibited breast cancer cell growth without interacting with IGFs4.
IGF I protects and rescues hippocampal neurons against ß-amyloid- and human amylin-induced toxicity - Insulin-like growth factors (IGF-I and IGF-II) are well known trophic factors and their specific receptors are uniquely distributed throughout the brain, being especially concentrated in the hippocampal formation. IGFs possess neurotrophic activities in the hippocampus, an area severely affected in Alzheimer disease. There is evidence that ß-amyloid (aß)-derived peptides likely play an important role in the neurodegenerative process observed in Alzheimer disease, it has been shown that IGFs can be neuroprotective to hippocampal neurons against toxicity induced by amyloidogenic derivatives5.
Reference:
1.Daughaday WH, Rotwein P (1989). Insulin-like growth factors I and II - Peptide, messenger ribonucleic acid and gene structures, serum, and tissue concentrations. Endocr. Rev, 10:68–91.
2.Jones JI, Clemmons DR (1995). Insulin-like growth factors and their binding proteins: biological actions. Endocr. Rev., 16:3–34.
3.Clemmons DR (1997). Insulin-like growth factor binding proteins and their role in controlling IGF actions. Cytokine Growth Factor Rev, 8:45–62.
4.Yu H, Rohan T (2000). Role of the Insulin-Like Growth Factor Family in Cancer Development and Progression. Journal of the National Cancer Institute., 92 (18):1472-1489.
5.Doré S, Kar S, Quirion R (1997). Insulin-like growth factor I protects and rescues hippocampal neurons against ß-amyloid- and human amylin-induced toxicity. Proc. Natl. Acad. Sci, 94:4772–4777.
Insulin-like growth factors (IGF)-1 and IGF-2 are ubiquitously expressed peptides with sequence homology to insulin.
Related Peptides
IGFs interacts with a specific receptor on the cell membrane, namely, the IGF-I receptor (IGF-IR), and the interaction is regulated by a group of specific binding proteins. All of these molecules are considered to be members of the IGF family, which includes the polypeptide ligands IGF-I and IGF-II, two types of cell membrane receptors (i.e., IGF-IR and IGF-IIR), and six IGF-binding proteins (i.e., IGFBP-1 through IGFBP-6).
Structural Characteristics
IGFs
IGF-I and IGF-II are single-chain polypeptides. The two molecules have 62% homology in their amino acid sequences. The molecules share additional structural similarities, and their structures resemble the structure of proinsulin1. IGF I consists of 70 amino acid residues, IGF I1 of 67, grouped into domains A and B (similar to insulin), C (analogous to the connecting peptide of proinsulin) and D (not present in insulins). The three intrachain disulfide bridges in IGF 1 and I1 have shown to be located in analogous positions to those in (pro) insulin1.
IGFBPs
The primary structures of mammalian IGFBPs appear to contain three distinct domains of roughly equivalent sizes: the conserved N-terminal domain, the highly variable midregion, and the conserved C-terminal domain.N-terminal domain contains 80–93 amino acid residues after the signal. Ten to 12 of the 16–20 cysteines found in the prepeptides are located within this domain. In IGFBP-1 to -5, these 12 cysteines are fully conserved, whereas in IGFBP-6, 10 of the 12 cysteines are invariant2.Midregion ranging in size from 55 amino acid residues to 95 amino acids separates the N-terminal domain from the C-terminal domain. The amino acid sequence for each midsegment appears to be unique to the protein. C-terminal region are highly conserved and, 6 cysteines of the total 16–20 cysteines are found in the C terminus and are strictly conserved2.
IGF Receptors
Both IGF-IR and IGF-IIR are glycoproteins and are located on the cell membrane. IGF-IR is a tetramer of two identical a-subunits and two identical ß-subunits. Structurally, IGF-IR resembles the insulin receptor, and there is 60% homology between them. IGF-IIR is monomeric. Three ligand-binding regions are found in the extracellular domain of the receptor, one for IGF-II binding and two for proteins containing mannose-6-phosphate (M6P), including renin, proliferin, thyroglobulin, and the latent form of (TGF)-ß transforming growth factor2.
Mode of Action
Binding of IGFs to IGF-IR activates the receptor's tyrosine kinase activity, which triggers a cascade of reactions. Two distinct signal transduction pathways have been identified for IGF-IR. One pathway activates Ras protein, Raf protein, and mitogen-activated protein kinase, and the other pathway involves phosphoinositol-3-kinase. IGF-IR is involved in cell transformation. In vitro experiments have shown that removal of IGF-IR from the cell membrane by eliminating the IGF-IR gene, by suppressing its expression, or by inhibiting its function can abolish cell transformation3. IGFBPs have multiple and complex functions. IGFBPs are able to inhibit or to enhance the action of IGFs, resulting in either suppression or stimulation of cell proliferation. These opposing effects of IGFBPs on IGFs are determined by the molecular structures of the binding proteins. When binding to IGFs, IGFBPs play three major roles: 1) transporting IGFs, 2) protecting IGFs from degradation, and 3) regulating the interaction between IGFs and IGF-IR. Normally, IGFBPs have higher binding affinity to IGFs than does IGF-IR; therefore, binding of IGFBPs to IGFs blocks the interaction between IGFs and IGF-IR and suppresses IGF action. However, binding of IGFBPs to IGFs also protects IGFs from proteolytic degradation, and that protection can enhance the action of IGFs by increasing their bioavailability in local tissue3.
Functions
Direct Involvement in Cancer - IGF-I and IGF-II are strong mitogens for a wide variety of cancer cell lines. Animal experiments indicate that overexpression of IGF-I increase the likelihood of tumor development in certain tissues. The effects of IGFs on cancer cells are mediated through IGF-IR. Eliminating IGF-IR from the cell membrane, blocking the interaction of IGFs with IGF-IR, or interrupting the signal transduction pathway of IGF-IR can abolish the mitogenic action of IGFs on cancer cells. IGF-IR is overexpressed in certain cancers, and its overexpression is associated with aggressive tumors. A recent study indicates that the insulin receptor is involved in mediating the actions of IGF-II on breast cancer. Cancer cells with a strong tendency to metastasize have higher expression of IGF-II and IGF-IR than those with a low ability to do so.In cancer, IGFBPs regulate the action of IGFs. In most situations, the binding proteins suppress the mitogenic action of IGFs and promote apoptosis. It has been shown that IGFBP-3 inhibited breast cancer cell growth without interacting with IGFs4.
IGF I protects and rescues hippocampal neurons against ß-amyloid- and human amylin-induced toxicity - Insulin-like growth factors (IGF-I and IGF-II) are well known trophic factors and their specific receptors are uniquely distributed throughout the brain, being especially concentrated in the hippocampal formation. IGFs possess neurotrophic activities in the hippocampus, an area severely affected in Alzheimer disease. There is evidence that ß-amyloid (aß)-derived peptides likely play an important role in the neurodegenerative process observed in Alzheimer disease, it has been shown that IGFs can be neuroprotective to hippocampal neurons against toxicity induced by amyloidogenic derivatives5.
Reference:
1.Daughaday WH, Rotwein P (1989). Insulin-like growth factors I and II - Peptide, messenger ribonucleic acid and gene structures, serum, and tissue concentrations. Endocr. Rev, 10:68–91.
2.Jones JI, Clemmons DR (1995). Insulin-like growth factors and their binding proteins: biological actions. Endocr. Rev., 16:3–34.
3.Clemmons DR (1997). Insulin-like growth factor binding proteins and their role in controlling IGF actions. Cytokine Growth Factor Rev, 8:45–62.
4.Yu H, Rohan T (2000). Role of the Insulin-Like Growth Factor Family in Cancer Development and Progression. Journal of the National Cancer Institute., 92 (18):1472-1489.
5.Doré S, Kar S, Quirion R (1997). Insulin-like growth factor I protects and rescues hippocampal neurons against ß-amyloid- and human amylin-induced toxicity. Proc. Natl. Acad. Sci, 94:4772–4777.
Inhibitors of FTase, GGTase
Definition
Farnesyltransferase inhibitors (FTIs) are a group of drugs that selectively inhibit the enzyme farnesyltransferase (FTase) that is responsible for the transfer of a farnesyl group to Ras and other proteins involved in signaling concerning cell transformation and survival.
Geranylgeranyl transferase type 1 inhibitor can affect critical cellular processes such as inhibition of platelet-derived growth factor receptor tyrosine kinase phosphorylation and growth arrest of human neoplastic cells in G1, presumably through inhibition of RhoA geranylgeranylation.
Methyltransferase inhibitors have ability to inhibit hypermethylation, restore suppressor gene expression and exert antitumor effects.
Structural Characteristics
Farnesyl protein transferase inhibitors - Initial approaches to FT inhibition involved the use of general inhibitors of isoprenylation. Synthesis of farnesyl groups can be blocked by the HMG CoA (i.e., 3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitors, such as lovastatin, and the mevalonate pyrophosphate decarboxylase inhibitor phenylacetate1.
The FTIs fall into three main classes: 1) the CAAX competitive inhibitors, 2) the FPP competitive inhibitors and 3) the bisubstrate inhibitors.
Peptidomimetic GGTIs have been described. These include aminobenzoic acid derivatives such as GGTI-298 and GGTI-2154 and benzoyleneurea-based compounds. Studies with these compounds have revealed a number of consequences of cellular exposure to a GGTI. Administration of GGTI to cells can cause cell cycle arrest at G0/G1, and this effect appears to be mediated by inactivation of CDK2/4 through the p21/p15 kinase inhibitors downstream of Rho. GGTIs are also potent stimulators of apoptosis in both normal and transformed cell lines2, 3.
DNA methyltransferase inhibitors - DNA methylation inhibitors have demonstrated the ability to inhibit hypermethylation, restore suppressor gene expression and exert antitumor effects. Four inhibitors, which are analogs of the nucleoside deoxycitidine, have been clinically tested: 5-azacytidine, 5-aza-2'-deoxycytidine, 1-ß-D-arabinofuranosyl-5-azacytosine and dihydro-5-azacytidine. The first two have demonstrated encouraging antileukemic activity but little activity in solid tumors, while the latter two are no longer under study due to lack of efficacy4.
Mode of Action
Farnesyl and Geranylgeranyl Transferase Inhibitors Induce G1 Arrest by Targeting the Proteasome - In a study, using breast tumor models, it has been shown those agents possessing a lactone moiety, including statins (such as lovastatin) and the isoprenoid inhibitors (such as FTI-277 and GGTI-298), mediate their cell cycle inhibitory activities by blocking the chymotrypsin activity of the proteasome. This results in the accumulation of cyclin-dependent kinase inhibitors p21 and p27 with subsequent G1 arrest. Cells devoid of p21 were refractory to the growth-inhibitory activity of lovastatin, FTI-277, and GGTI-298. However, in p21 null cells, isoprenylation of key substrates of farnesyl transferase (such as Ras) and of geranylgeranyl transferase (such as RAP-1) were inhibited by FTI-277 and GGTI-298, respectively, suggesting that although both these isoprenoid inhibitors reached and inhibited their intended targets, inhibition of the isoprenylation of Ras and RAP-1A are not sufficient to mediate G1 arrest5.
DNA methyltransferase inhibitors - These drugs act by preventing methylation. Decitabine, for example, when incorporated into DNA, covalently link with DNMT which may induce cell death by obstructing DNA synthesis. They may also induce DNA damage through structural instability at the site of incorporation6.
Functions
Farnesyltransferase and geranylgeranyltransferase I inhibitors upregulate RhoB expression – it has been demonstrate that the novel antitumor agents farnesyltransferase inhibitors (FTIs) and geranylgeranyltransferase I inhibitors (GGTIs) upregulate RhoB expression in a wide spectrum of human cancer cells including those from pancreatic, breast, lung, colon, bladder and brain cancers. RhoB induction by FTI-277 and GGTI-298 occurs at the transcriptional level and is blocked by actinomycin D. Reverse transcription-PCR experiments documented that the increase in RhoB protein levels is due to an increase in RhoB transcription. Furthermore, treatment with FTIs and GGTIs of cancer cells results in HDAC1 dissociation, HAT association and histone acetylation of the RhoB promoter. Thus, promoter acetylation is a novel mechanism by which RhoB expression levels are regulated following treatment with the anticancer agents FTIs and GGTIs7.
DNA methyltransferase inhibitor, induces ATR-mediated DNA double-strand break responses, apoptosis, and synergistic cytotoxicity with doxorubicin and bortezomib against multiple myeloma cells - In a study, 5-azacytidine, a DNA methyltransferase inhibitor showed significant cytotoxicity against both conventional therapy-sensitive and therapy-resistant MM cell lines, as well as multidrug-resistant patient-derived MM cells, with IC50 of 0.8–3 µmol/L. Conversely, 5-azacytidine was not cytotoxic to peripheral blood mononuclear cells or patient-derived bone marrow stromal cells (BMSC) at these doses. 5-Azacytidine treatment induced DNA double-strand break (DSB) responses, as evidenced by H2AX, Chk2, and p53 phosphorylations, and apoptosis of MM cells. Further it has been shown that 5-azacytidine–induced DNA DSB responses were mediated predominantly by ATR, and that doxorubicin, as well as bortezomib, synergistically enhanced 5-azacytidine–induced MM cell death8.
References:
1.End DW (1999). Farnesyl protein transferase inhibitors and other therapies targeting the Ras signal transduction pathway. Invest. New. Drugs, 17:241–258.
2.Lerner EC, Qian Y, Hamilton AD, Sebti SM (1995). Disruption of oncogenic K-Ras4B processing and signaling by a potent geranylgeranyltranferase I inhibitor. J. Biol. Chem, 270:26770–26773.
3.Vasudevan A, Qian Y, Vogt A, Blaskovich MA, Ohkanda J, Sebti SM, Hamilton AD (1995). Potent, highly selective, and non-thiol inhibitors of protein geranylgeranyltransferase-I. J Med Chem, 42:1333–1340.
4.Goffin J, Eisenhauer E (2002). DNA methyltransferase inhibitors—state of the art. Annals of Oncology, 13:1699-1716.
5.Efuet ET, Keyomarsi K (2006). Farnesyl and Geranylgeranyl Transferase Inhibitors Induce G1 Arrest by Targeting the Proteasome. Cancer Research, 66(2): 1040-1051.
6.Juttermann R, Li E, Jaenisch R (1994). Toxicity of 5-aza-2'-deoxycytidine to mammalian cells is mediated primarily by covalent trapping of DNA methyltransferase rather than DNA demethylation. Proc Natl Acad Sci, 91(25): 11797–11801.
7.Delarue FL, Adnane J, Joshi B, Blaskovich MA, Wang DA, Hawker J, Bizouarn F, Ohkanda J, Zhu K, Hamilton AD, Chellappan S, Sebti SM (2006). Farnesyltransferase and geranylgeranyltransferase I inhibitors upregulate RhoB expression by HDAC1 dissociation, HAT association and histone acetylation of the RhoB promoter. Oncogene, 1;26(5):633-40.
8.Kiziltepe T, Hideshima T, Catley L, Raje N, Yasui H, Shiraishi N, Okawa Y, Ikeda H, Vallet S, Pozzi S, Ishitsuka K, Ocio EM, Chauhan D, Anderson KC (2007). 5-Azacytidine, a DNA methyltransferase inhibitor, induces ATR-mediated DNA double-strand break responses, apoptosis, and synergistic cytotoxicity with doxorubicin and bortezomib against multiple myeloma cells. Mol. Cancer. Ther. 6(6):1718–1727.
Farnesyltransferase inhibitors (FTIs) are a group of drugs that selectively inhibit the enzyme farnesyltransferase (FTase) that is responsible for the transfer of a farnesyl group to Ras and other proteins involved in signaling concerning cell transformation and survival.
Geranylgeranyl transferase type 1 inhibitor can affect critical cellular processes such as inhibition of platelet-derived growth factor receptor tyrosine kinase phosphorylation and growth arrest of human neoplastic cells in G1, presumably through inhibition of RhoA geranylgeranylation.
Methyltransferase inhibitors have ability to inhibit hypermethylation, restore suppressor gene expression and exert antitumor effects.
Structural Characteristics
Farnesyl protein transferase inhibitors - Initial approaches to FT inhibition involved the use of general inhibitors of isoprenylation. Synthesis of farnesyl groups can be blocked by the HMG CoA (i.e., 3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitors, such as lovastatin, and the mevalonate pyrophosphate decarboxylase inhibitor phenylacetate1.
The FTIs fall into three main classes: 1) the CAAX competitive inhibitors, 2) the FPP competitive inhibitors and 3) the bisubstrate inhibitors.
Peptidomimetic GGTIs have been described. These include aminobenzoic acid derivatives such as GGTI-298 and GGTI-2154 and benzoyleneurea-based compounds. Studies with these compounds have revealed a number of consequences of cellular exposure to a GGTI. Administration of GGTI to cells can cause cell cycle arrest at G0/G1, and this effect appears to be mediated by inactivation of CDK2/4 through the p21/p15 kinase inhibitors downstream of Rho. GGTIs are also potent stimulators of apoptosis in both normal and transformed cell lines2, 3.
DNA methyltransferase inhibitors - DNA methylation inhibitors have demonstrated the ability to inhibit hypermethylation, restore suppressor gene expression and exert antitumor effects. Four inhibitors, which are analogs of the nucleoside deoxycitidine, have been clinically tested: 5-azacytidine, 5-aza-2'-deoxycytidine, 1-ß-D-arabinofuranosyl-5-azacytosine and dihydro-5-azacytidine. The first two have demonstrated encouraging antileukemic activity but little activity in solid tumors, while the latter two are no longer under study due to lack of efficacy4.
Mode of Action
Farnesyl and Geranylgeranyl Transferase Inhibitors Induce G1 Arrest by Targeting the Proteasome - In a study, using breast tumor models, it has been shown those agents possessing a lactone moiety, including statins (such as lovastatin) and the isoprenoid inhibitors (such as FTI-277 and GGTI-298), mediate their cell cycle inhibitory activities by blocking the chymotrypsin activity of the proteasome. This results in the accumulation of cyclin-dependent kinase inhibitors p21 and p27 with subsequent G1 arrest. Cells devoid of p21 were refractory to the growth-inhibitory activity of lovastatin, FTI-277, and GGTI-298. However, in p21 null cells, isoprenylation of key substrates of farnesyl transferase (such as Ras) and of geranylgeranyl transferase (such as RAP-1) were inhibited by FTI-277 and GGTI-298, respectively, suggesting that although both these isoprenoid inhibitors reached and inhibited their intended targets, inhibition of the isoprenylation of Ras and RAP-1A are not sufficient to mediate G1 arrest5.
DNA methyltransferase inhibitors - These drugs act by preventing methylation. Decitabine, for example, when incorporated into DNA, covalently link with DNMT which may induce cell death by obstructing DNA synthesis. They may also induce DNA damage through structural instability at the site of incorporation6.
Functions
Farnesyltransferase and geranylgeranyltransferase I inhibitors upregulate RhoB expression – it has been demonstrate that the novel antitumor agents farnesyltransferase inhibitors (FTIs) and geranylgeranyltransferase I inhibitors (GGTIs) upregulate RhoB expression in a wide spectrum of human cancer cells including those from pancreatic, breast, lung, colon, bladder and brain cancers. RhoB induction by FTI-277 and GGTI-298 occurs at the transcriptional level and is blocked by actinomycin D. Reverse transcription-PCR experiments documented that the increase in RhoB protein levels is due to an increase in RhoB transcription. Furthermore, treatment with FTIs and GGTIs of cancer cells results in HDAC1 dissociation, HAT association and histone acetylation of the RhoB promoter. Thus, promoter acetylation is a novel mechanism by which RhoB expression levels are regulated following treatment with the anticancer agents FTIs and GGTIs7.
DNA methyltransferase inhibitor, induces ATR-mediated DNA double-strand break responses, apoptosis, and synergistic cytotoxicity with doxorubicin and bortezomib against multiple myeloma cells - In a study, 5-azacytidine, a DNA methyltransferase inhibitor showed significant cytotoxicity against both conventional therapy-sensitive and therapy-resistant MM cell lines, as well as multidrug-resistant patient-derived MM cells, with IC50 of 0.8–3 µmol/L. Conversely, 5-azacytidine was not cytotoxic to peripheral blood mononuclear cells or patient-derived bone marrow stromal cells (BMSC) at these doses. 5-Azacytidine treatment induced DNA double-strand break (DSB) responses, as evidenced by H2AX, Chk2, and p53 phosphorylations, and apoptosis of MM cells. Further it has been shown that 5-azacytidine–induced DNA DSB responses were mediated predominantly by ATR, and that doxorubicin, as well as bortezomib, synergistically enhanced 5-azacytidine–induced MM cell death8.
References:
1.End DW (1999). Farnesyl protein transferase inhibitors and other therapies targeting the Ras signal transduction pathway. Invest. New. Drugs, 17:241–258.
2.Lerner EC, Qian Y, Hamilton AD, Sebti SM (1995). Disruption of oncogenic K-Ras4B processing and signaling by a potent geranylgeranyltranferase I inhibitor. J. Biol. Chem, 270:26770–26773.
3.Vasudevan A, Qian Y, Vogt A, Blaskovich MA, Ohkanda J, Sebti SM, Hamilton AD (1995). Potent, highly selective, and non-thiol inhibitors of protein geranylgeranyltransferase-I. J Med Chem, 42:1333–1340.
4.Goffin J, Eisenhauer E (2002). DNA methyltransferase inhibitors—state of the art. Annals of Oncology, 13:1699-1716.
5.Efuet ET, Keyomarsi K (2006). Farnesyl and Geranylgeranyl Transferase Inhibitors Induce G1 Arrest by Targeting the Proteasome. Cancer Research, 66(2): 1040-1051.
6.Juttermann R, Li E, Jaenisch R (1994). Toxicity of 5-aza-2'-deoxycytidine to mammalian cells is mediated primarily by covalent trapping of DNA methyltransferase rather than DNA demethylation. Proc Natl Acad Sci, 91(25): 11797–11801.
7.Delarue FL, Adnane J, Joshi B, Blaskovich MA, Wang DA, Hawker J, Bizouarn F, Ohkanda J, Zhu K, Hamilton AD, Chellappan S, Sebti SM (2006). Farnesyltransferase and geranylgeranyltransferase I inhibitors upregulate RhoB expression by HDAC1 dissociation, HAT association and histone acetylation of the RhoB promoter. Oncogene, 1;26(5):633-40.
8.Kiziltepe T, Hideshima T, Catley L, Raje N, Yasui H, Shiraishi N, Okawa Y, Ikeda H, Vallet S, Pozzi S, Ishitsuka K, Ocio EM, Chauhan D, Anderson KC (2007). 5-Azacytidine, a DNA methyltransferase inhibitor, induces ATR-mediated DNA double-strand break responses, apoptosis, and synergistic cytotoxicity with doxorubicin and bortezomib against multiple myeloma cells. Mol. Cancer. Ther. 6(6):1718–1727.
Hydrins
Definition
Hydrins 1 and 2 have been isolated from the pituitary glands of Xenopus laevis and Rana esculenta, respectively. It is assumed that the hydrins could be involved in the water-electrolyte regulation of amphibians.
Discovery
Earlier reports show that neurohypophysial extracts of anurans contain a third class of peptides. Isolation of neurohypophysial peptides by high pressure liquid chromatography (HPLC) from a number of anuran Amphibia has revealed the presence of peptides that is not detected in other non-mammalian tetrapods. These peptides were sequenced and named “hydrins” in 1989.
Structural Characteristics
Hydrins seem to be derived from the pro-vasotocin-neurophysin precursor. The differential maturation of provasotocin leads to processing-arrested intermediates, namely vasotocinyl-Gly (Hydrin 2) in virtually all anuran amphibians and vasotocinyl-Gly-Lys-Arg (Hydrin 1) in Xenopus laevis. These intermediates result from a down regulation of the alpha-amidating enzyme or carboxypeptidase E, respectively. Hydrins, in contrast to vasotocin, are not active on rat uterus or rat blood pressure. They are absent from other vasotocin bearers such as birds and could be involved specifically in water-electrolyte regulation of amphibians1.
Mode of Action
Distinct hydroosmotic receptors for the neurohypophyseal peptides vasotocin and Hydrins: A comparative study was conducted to examine the biological properties of vasotocin, hydrin 1 (vasotocinyl-Gly-Lys-Arg) and hydrin 2 (vasotocinyl-Gly), in particular the hydro-osmotic activities on the frog skin, the frog urinary bladder and the frog kidney. It has been shown that Hydrins are as active as or more active than vasotocin on the first two organs but they are virtually devoid of antidiuretic activity in the rat and the frog, in contrast to vasotocin. Further, it appears that where the oxytocin ring (residues 1-6), present in the three peptides, is necessary for the action on the three organs, the C-terminal amidated group of vasotocin is necessary for the renal receptor but not for the skin and bladder receptors. It has been suggested that adaptation has led to specialization of (at least) two subtypes of hydro-osmotic V2 receptors, the renal subtype on which vasotocin is mainly active for the reabsorption of tubular water, and the skin/bladder subtype on which hydrin 2 is specifically involved in ensuring the rehydration of the animal2.
Functions
Effects of hydrin2 on cutaneous electrical properties of Rana pipiens -
In a study, electrical properties were measured in isolated skin patches from leopard frogs (Rana pipiens) to explore the possibility that hydrin 2 (vasotocinyl-gly) may regulate cutaneous ion transport. Hydrin 2 is a neurohypophysial peptide commonly implicated in rehydration of anurans. Experimental frogs were given either one or two intraperitoneal (i.p.) injections of hydrin 2 in saline solution, each calculated to achieve a final blood concentration of 81 ng/ml. After a 2-h equilibration period, the frogs were euthanized and abdominal skin removed and used for study. Results of this study confirm that exposure of R. pipiens to hydrin 2 promotes a highly significant increase in transepithelial potential (TEP) and short-circuit current (Isc).In a dose–response study, 10-fold increases in serosal hydrin 2 concentration triggered significant changes in TEP and Isc, with maximal responses observed at 10 ng/ml. Because hydrin 2 is known to facilitate “cutaneous drinking” in anurans, this study suggests a correlation between ion and water transport across the skin3.
A fluorescent analogue of hydrin 1: a new probe for vasotocin receptors - In a study, deamino and fluorescein analogues of hydrin 1 were used to characterize their physiological action in the urinary bladder of the toad, Bufo marinus. It was shown that 1-Deamino-hydrin 1 (d-hydrin) was more potent than vasotocin in stimulating osmotic water flow across intact bladders and more potent than vasotocin in displacing tritium-labeled vasopressin [(3H] AVP) from cell membranes. Furthermore, 1-Deamino-[11-lysine (fluorescein)]-hydrin 1 (flu-hydrin) was found to be the most potent fluorescent vasotocin receptor probe synthesized to date. Flu-hydrin increased osmotic water flow across bladders with a half-maximal effective dose (ED50) value of 6 x 10(-10) M and displaced [3H]AVP from membranes with a half-maximal concentration (IC50) value of 3 x 10(-9) M. This study shows that d-hydrin can serve as a foundation molecule to which reporter groups, such as fluorescent residues, can be attached with better preservation of hydrosmotic activity than is possible with similar modifications of vasotocin4.
References
1.Rouille Y, Michel G, Chauvet MT, Chauvet J, Acher R (1989). Hydrins, hydroosmotic neurohypophyseal peptides osmoregulatory adaptation in amphibians through vasotocin precursor processing. Proc. Natl. Acad. Sci, 86:5272–5275.
2.Rouille Y, Ouedraogo Y, Chauvet J, Acher R (1995). Distinct hydroosmotic receptors for the neurohypophyseal peptides vasotocin and hydrins in the frog Rana esculenta. Neuropeptides, 29:301–307.
3.Ford NA, Robinson GD (2003). Effects of hydrin 2 on cutaneous electrical properties of Rana pipiens. General and Comparative Endocrinology, 134 (2):103-108.
4.Eggena P, Ma CL, Lu MQ, Buku A (1990). A fluorescent analogue of hydrin 1: a new probe for vasotocin receptors. Am J Physiol Endocrinol Metab, 259:524-528.
Hydrins 1 and 2 have been isolated from the pituitary glands of Xenopus laevis and Rana esculenta, respectively. It is assumed that the hydrins could be involved in the water-electrolyte regulation of amphibians.
Discovery
Earlier reports show that neurohypophysial extracts of anurans contain a third class of peptides. Isolation of neurohypophysial peptides by high pressure liquid chromatography (HPLC) from a number of anuran Amphibia has revealed the presence of peptides that is not detected in other non-mammalian tetrapods. These peptides were sequenced and named “hydrins” in 1989.
Structural Characteristics
Hydrins seem to be derived from the pro-vasotocin-neurophysin precursor. The differential maturation of provasotocin leads to processing-arrested intermediates, namely vasotocinyl-Gly (Hydrin 2) in virtually all anuran amphibians and vasotocinyl-Gly-Lys-Arg (Hydrin 1) in Xenopus laevis. These intermediates result from a down regulation of the alpha-amidating enzyme or carboxypeptidase E, respectively. Hydrins, in contrast to vasotocin, are not active on rat uterus or rat blood pressure. They are absent from other vasotocin bearers such as birds and could be involved specifically in water-electrolyte regulation of amphibians1.
Mode of Action
Distinct hydroosmotic receptors for the neurohypophyseal peptides vasotocin and Hydrins: A comparative study was conducted to examine the biological properties of vasotocin, hydrin 1 (vasotocinyl-Gly-Lys-Arg) and hydrin 2 (vasotocinyl-Gly), in particular the hydro-osmotic activities on the frog skin, the frog urinary bladder and the frog kidney. It has been shown that Hydrins are as active as or more active than vasotocin on the first two organs but they are virtually devoid of antidiuretic activity in the rat and the frog, in contrast to vasotocin. Further, it appears that where the oxytocin ring (residues 1-6), present in the three peptides, is necessary for the action on the three organs, the C-terminal amidated group of vasotocin is necessary for the renal receptor but not for the skin and bladder receptors. It has been suggested that adaptation has led to specialization of (at least) two subtypes of hydro-osmotic V2 receptors, the renal subtype on which vasotocin is mainly active for the reabsorption of tubular water, and the skin/bladder subtype on which hydrin 2 is specifically involved in ensuring the rehydration of the animal2.
Functions
Effects of hydrin2 on cutaneous electrical properties of Rana pipiens -
In a study, electrical properties were measured in isolated skin patches from leopard frogs (Rana pipiens) to explore the possibility that hydrin 2 (vasotocinyl-gly) may regulate cutaneous ion transport. Hydrin 2 is a neurohypophysial peptide commonly implicated in rehydration of anurans. Experimental frogs were given either one or two intraperitoneal (i.p.) injections of hydrin 2 in saline solution, each calculated to achieve a final blood concentration of 81 ng/ml. After a 2-h equilibration period, the frogs were euthanized and abdominal skin removed and used for study. Results of this study confirm that exposure of R. pipiens to hydrin 2 promotes a highly significant increase in transepithelial potential (TEP) and short-circuit current (Isc).In a dose–response study, 10-fold increases in serosal hydrin 2 concentration triggered significant changes in TEP and Isc, with maximal responses observed at 10 ng/ml. Because hydrin 2 is known to facilitate “cutaneous drinking” in anurans, this study suggests a correlation between ion and water transport across the skin3.
A fluorescent analogue of hydrin 1: a new probe for vasotocin receptors - In a study, deamino and fluorescein analogues of hydrin 1 were used to characterize their physiological action in the urinary bladder of the toad, Bufo marinus. It was shown that 1-Deamino-hydrin 1 (d-hydrin) was more potent than vasotocin in stimulating osmotic water flow across intact bladders and more potent than vasotocin in displacing tritium-labeled vasopressin [(3H] AVP) from cell membranes. Furthermore, 1-Deamino-[11-lysine (fluorescein)]-hydrin 1 (flu-hydrin) was found to be the most potent fluorescent vasotocin receptor probe synthesized to date. Flu-hydrin increased osmotic water flow across bladders with a half-maximal effective dose (ED50) value of 6 x 10(-10) M and displaced [3H]AVP from membranes with a half-maximal concentration (IC50) value of 3 x 10(-9) M. This study shows that d-hydrin can serve as a foundation molecule to which reporter groups, such as fluorescent residues, can be attached with better preservation of hydrosmotic activity than is possible with similar modifications of vasotocin4.
References
1.Rouille Y, Michel G, Chauvet MT, Chauvet J, Acher R (1989). Hydrins, hydroosmotic neurohypophyseal peptides osmoregulatory adaptation in amphibians through vasotocin precursor processing. Proc. Natl. Acad. Sci, 86:5272–5275.
2.Rouille Y, Ouedraogo Y, Chauvet J, Acher R (1995). Distinct hydroosmotic receptors for the neurohypophyseal peptides vasotocin and hydrins in the frog Rana esculenta. Neuropeptides, 29:301–307.
3.Ford NA, Robinson GD (2003). Effects of hydrin 2 on cutaneous electrical properties of Rana pipiens. General and Comparative Endocrinology, 134 (2):103-108.
4.Eggena P, Ma CL, Lu MQ, Buku A (1990). A fluorescent analogue of hydrin 1: a new probe for vasotocin receptors. Am J Physiol Endocrinol Metab, 259:524-528.
Histocompatibility Antigens
Definition
Histocompatibility molecules are glycoproteins expressed at the surface of almost all vertebrate cells. They get their name because they are responsible for the compatibility or rather the lack of it — of the tissues of genetically different individuals. Monozygotic ("identical") human twins have the same histocompatibility molecules on their cells, and they can accept transplants of tissue from each other. So the histocompatibility molecules of one individual act as antigens when introduced into a different individual. In fact, the histocompatibility molecules are often called histocompatibility antigens or transplantation antigens.
Structural Characteristics
Located in the short arm of chromosome 6, HLA is composed of more than 200 genes, of which about 20% codify histocompatibility molecules expressed on the cell surface.2 These genes, which take part in the immunologic response, are didactically divided into three classes: I, II and III, being different between themselves as to structure and function.3 Class I region has three main loci: HLA-A, HLA-B and HLA-C, whereas class II HLA contains the HLA-DR, HLA-DQ and HLA-DP loci. Class I and II HLA genes codify classical histocompatibility molecules. Class III HLA genes codify complement factors, tumor necrosis factor and 21-hydroxylase enzyme, among others.
Structure of crossreactive human histocompatibility antigens HLAA28 and HLA-A2: Possible implications for the generation of HLA polymorphism - The primary structure of two highly crossreactive human histocompatibility antigen, HLA-A28 and HLA-A2, has been determined to 96% and 90%, respectively, of the papain solubilized molecules. Their sequences have been compared with the sequence of HLA-B7 and with each other in order to outline the sites of diversity. The overall homology between HLA-B7 and these HLA-A antigens is 86%. A large majority of the differences are located between residues 43 and 195. Within this area, substitutions cluster in at least three segments-residues 65-80, 105-116, and 177-194. HLA-A28 and HLA-A2 show 96% homology. Most of the differences fall within segments 65-74 and 107-116. it has been shown that residues in these segments are integral parts of the alloantigenic determinants of HLA-A28 and HLA-A2. It is further proposed that these three clusters may constitute major, albeit not exclusive, sites of antigenic diversity in human histocompatibility antigens. The nature of the differences among HLA-B7, HLA-A28, and HLA-A2 in the first variable segment suggests that gene conversion might play some role in the generation of HIA polymorphism1.
Mode of Action
The role of HLA Class I molecules is to take these virally induced peptides to the surface of the cell and by linking to the T-Cell receptor of a Cytotoxic (CD8) T Cell, demonstrate the presence of this virus. The CD8T Cell will now be “educated” and it will be able to initiate the process of killing cells which subsequently has that same viral protein/HLA Class I molecule on its surface2, 3. The expression of HLA Class II, on cells, which would not normally express them, is stimulated by cytokines like interferon g and in a transplant, this is associated with acute graft destruction.HLA Class II molecules consist of two chains each encoded by genes in the “HLA Complex” on Chromosome 6. The T Cells, which link up to the HLA Class II molecules, are Helper (CD4) T cells. Thus the “education” process which occurs from HLA Class II presentation, involves the helper-function of setting up a general immune reaction which will involve cytokines, cellular and humoral defense against the bacterial (or other) invasion2, 3.
Functions
Associoation of HLA with Lupus erythematosus - Lupus erythematosus is an autoimmune disorder with a wide spectrum of clinical manifestations ranging from the cutaneous forms (CLE) to the multisystemic disease. Experimental studies suggest a strong association with polymorphic genes codifying immunoregulatory molecules (e.g., HLA, TNF-a complement), especially in patients anti-Ro-positive. HLA-B8 and –DR3 antigens were associated with the development of SCLE. In some studies, HLA-DR3 antigen was detected in more than 50% of patients with SCLE4.
Influence of human histocompatibility antigens on susceptibility to and clinical expression of psychiatric diseases (Bipolar disorder) - The antigen HLA-B16 has been generally associated with mood disorders, including maniac and purely depressive disorders. The antigens HLA-A10, HLA-A29, HLA-B7, HLA-B16 and HLA-B21 have been more frequently found in patients with bipolar disorder, compared with healthy controls5. Lithium is a mood-stabilizing agent often used for the treatment of bipolar disorder. Some researches have suggested that, as other chemotherapy agents, this drug may change the expression of HLA molecules. The two main HLA classes seem to be affected differently by the drug; changes in class II HLA are more significant from the functional perspective. Reduction and loss of expression of class I histocompatibility molecules on the cell surface have been reported, whereas changes in class II HLA have occurred at the genomic DNA level. It is still unknown how lithium is able to cause these changes, which may be present 2 weeks after taking the drug in usual therapeutic doses6.
References
1.López de Castro JA, Strominger JL, Strong DM, Orr HT (1982). Structure of crossreactive human histocompatibility antigens HLAA28 and HLA-A2: Possible implications for the generation of HLA polymorphism. Proc. Natl. Acad. Sci, 79:3813-3817.
2.Shankarkumar U, Ghosh K, Mohanty D (2002). The Human Leukocyte Antigen (HLA) System. J Assoc Physicians, 50:916-926.
3.Book: HLA and MHC: Genes, Molecules and Function. By Browning M, Mc Michael
4.Provost TT, Watson R (1993). Anti-Ro (SS-A) HLA-DR3-positive women: the interrelationship between some ANA negative, SS, SCLE, and NLE mothers and SS/LE overlap female patients. J. Invest. Dermatol, 100: 14-20.
5.Ucok A, Akar U, Polat A, Yazici O (2005). Human leukocyte antigen alleles in patients with bipolar disorder in Turkey. Eur. Psychiatry., 20(1):83.
6.Kang BJ, Park SW, Chung TH (2000). Can the expression of histocompatibility antigen be changed by lithium?. Bipolar. Disord, 2(2):140-144.
Histocompatibility molecules are glycoproteins expressed at the surface of almost all vertebrate cells. They get their name because they are responsible for the compatibility or rather the lack of it — of the tissues of genetically different individuals. Monozygotic ("identical") human twins have the same histocompatibility molecules on their cells, and they can accept transplants of tissue from each other. So the histocompatibility molecules of one individual act as antigens when introduced into a different individual. In fact, the histocompatibility molecules are often called histocompatibility antigens or transplantation antigens.
Structural Characteristics
Located in the short arm of chromosome 6, HLA is composed of more than 200 genes, of which about 20% codify histocompatibility molecules expressed on the cell surface.2 These genes, which take part in the immunologic response, are didactically divided into three classes: I, II and III, being different between themselves as to structure and function.3 Class I region has three main loci: HLA-A, HLA-B and HLA-C, whereas class II HLA contains the HLA-DR, HLA-DQ and HLA-DP loci. Class I and II HLA genes codify classical histocompatibility molecules. Class III HLA genes codify complement factors, tumor necrosis factor and 21-hydroxylase enzyme, among others.
Structure of crossreactive human histocompatibility antigens HLAA28 and HLA-A2: Possible implications for the generation of HLA polymorphism - The primary structure of two highly crossreactive human histocompatibility antigen, HLA-A28 and HLA-A2, has been determined to 96% and 90%, respectively, of the papain solubilized molecules. Their sequences have been compared with the sequence of HLA-B7 and with each other in order to outline the sites of diversity. The overall homology between HLA-B7 and these HLA-A antigens is 86%. A large majority of the differences are located between residues 43 and 195. Within this area, substitutions cluster in at least three segments-residues 65-80, 105-116, and 177-194. HLA-A28 and HLA-A2 show 96% homology. Most of the differences fall within segments 65-74 and 107-116. it has been shown that residues in these segments are integral parts of the alloantigenic determinants of HLA-A28 and HLA-A2. It is further proposed that these three clusters may constitute major, albeit not exclusive, sites of antigenic diversity in human histocompatibility antigens. The nature of the differences among HLA-B7, HLA-A28, and HLA-A2 in the first variable segment suggests that gene conversion might play some role in the generation of HIA polymorphism1.
Mode of Action
The role of HLA Class I molecules is to take these virally induced peptides to the surface of the cell and by linking to the T-Cell receptor of a Cytotoxic (CD8) T Cell, demonstrate the presence of this virus. The CD8T Cell will now be “educated” and it will be able to initiate the process of killing cells which subsequently has that same viral protein/HLA Class I molecule on its surface2, 3. The expression of HLA Class II, on cells, which would not normally express them, is stimulated by cytokines like interferon g and in a transplant, this is associated with acute graft destruction.HLA Class II molecules consist of two chains each encoded by genes in the “HLA Complex” on Chromosome 6. The T Cells, which link up to the HLA Class II molecules, are Helper (CD4) T cells. Thus the “education” process which occurs from HLA Class II presentation, involves the helper-function of setting up a general immune reaction which will involve cytokines, cellular and humoral defense against the bacterial (or other) invasion2, 3.
Functions
Associoation of HLA with Lupus erythematosus - Lupus erythematosus is an autoimmune disorder with a wide spectrum of clinical manifestations ranging from the cutaneous forms (CLE) to the multisystemic disease. Experimental studies suggest a strong association with polymorphic genes codifying immunoregulatory molecules (e.g., HLA, TNF-a complement), especially in patients anti-Ro-positive. HLA-B8 and –DR3 antigens were associated with the development of SCLE. In some studies, HLA-DR3 antigen was detected in more than 50% of patients with SCLE4.
Influence of human histocompatibility antigens on susceptibility to and clinical expression of psychiatric diseases (Bipolar disorder) - The antigen HLA-B16 has been generally associated with mood disorders, including maniac and purely depressive disorders. The antigens HLA-A10, HLA-A29, HLA-B7, HLA-B16 and HLA-B21 have been more frequently found in patients with bipolar disorder, compared with healthy controls5. Lithium is a mood-stabilizing agent often used for the treatment of bipolar disorder. Some researches have suggested that, as other chemotherapy agents, this drug may change the expression of HLA molecules. The two main HLA classes seem to be affected differently by the drug; changes in class II HLA are more significant from the functional perspective. Reduction and loss of expression of class I histocompatibility molecules on the cell surface have been reported, whereas changes in class II HLA have occurred at the genomic DNA level. It is still unknown how lithium is able to cause these changes, which may be present 2 weeks after taking the drug in usual therapeutic doses6.
References
1.López de Castro JA, Strominger JL, Strong DM, Orr HT (1982). Structure of crossreactive human histocompatibility antigens HLAA28 and HLA-A2: Possible implications for the generation of HLA polymorphism. Proc. Natl. Acad. Sci, 79:3813-3817.
2.Shankarkumar U, Ghosh K, Mohanty D (2002). The Human Leukocyte Antigen (HLA) System. J Assoc Physicians, 50:916-926.
3.Book: HLA and MHC: Genes, Molecules and Function. By Browning M, Mc Michael
4.Provost TT, Watson R (1993). Anti-Ro (SS-A) HLA-DR3-positive women: the interrelationship between some ANA negative, SS, SCLE, and NLE mothers and SS/LE overlap female patients. J. Invest. Dermatol, 100: 14-20.
5.Ucok A, Akar U, Polat A, Yazici O (2005). Human leukocyte antigen alleles in patients with bipolar disorder in Turkey. Eur. Psychiatry., 20(1):83.
6.Kang BJ, Park SW, Chung TH (2000). Can the expression of histocompatibility antigen be changed by lithium?. Bipolar. Disord, 2(2):140-144.
Hepatitis C Virus (HCV) Peptides
Definition
Hepatitis C virus (HCV) belongs to the genus Hepacivirus in the family Flaviviridae and possesses a viral genome consisting of a single, positive-strand RNA. The genome encodes a large precursor polyprotein of approximately 3,000 amino acids which is processed into at least 10 viral proteins by host and viral proteases.
Discovery
HCV was discovered by Choo et al., 1989 by investigators at Chiron. Portions of the HCV genome were isolated by screening cDNA expression libraries made from RNA and DNA from chimpanzees infected with serum from a patient with post-transfusion non-A, non-B hepatitis. To identify portions of the genome that encoded viral proteins, the libraries were screened with antibodies from patients who had non-A, non-B hepatitis1.
Structural Characteristics
HCV belongs to the genus Hepacivirus in the family Flaviviridae and possesses a viral genome consisting of a single, positive-strand RNA with a nucleotide length of about 9.4 kb. The genome encodes a large precursor polyprotein of approximately 3,000 amino acids. The polyprotein is processed co- and posttranslationally into at least 10 viral proteins by host and viral proteases. The structural proteins of HCV are located in the N-terminal one-fourth of the polyprotein and are cleaved by host membrane proteases2. HCV core protein forms the nucleocapsid, which is surrounded by the envelope containing E1 and E2 glycoproteins3. It has been suggested that HCV core protein is a multifunctional molecule that acts as a structural protein but is also involved in the pathogenesis of hepatitis C. HCV core protein has two major p23 and p21 forms4. HCV core protein p23 represents a 191-amino-acid product in which the C-terminal hydrophobic region also acts as a signal sequence for E1. HCV polyprotein is cleaved between residues 191 and 192 by host signal peptidase to generate C-terminal and N-terminal polypeptides encompassing the core and E1 proteins, respectively. For the full maturation of HCV core protein, the C-terminal signal-anchor sequence was thought to be further processed by an unidentified microsomal protease, and the 21-kDa isoform of core protein is predominantly detected both in cultured cells by transfection with expression plasmid and in viral particles obtained from sera of patients with hepatitis C. These results suggest that p21 is the mature form of HCV core protein3.
Functions
HCV core protein upregulates serine phosphorylation of insulin receptor substrate-1 and impairs the downstream Akt/PKB signaling pathway for insulin resistance - Insulin resistance is a critical component of type 2 diabetes mellitus (T2DM) pathogenesis. Several mechanisms are likely to be involved in the pathogenesis of HCV-related insulin resistance. Since previously it was observed that HCV core protein activates c-Jun N-terminal kinase (JNK) and mitogen-activated protein kinase, a study was conducted to examine the contribution of these pathways to insulin resistance in hepatocytes4. It was found that HCV core protein alone or in the presence of other viral proteins increases Ser312 phosphorylation of the insulin receptor substrate-1 (IRS-1). Hepatocytes infected with cell culture-grown HCV genotype 1a or 2a displayed a significant increase in the Ser473 phosphorylation status of the Ser/Thr kinase protein kinase B (Akt/PKB), while Thr308 phosphorylation was not significantly altered. HCV core protein-mediated Ser312 phosphorylation of IRS-1 was inhibited by JNK (SP600125) and phosphatidylinositol-3 kinase (LY294002) inhibitors. Furthermore, a functional assay also suggested that hepatocytes expressing HCV core protein alone or infected with cell culture-grown HCV exhibited a suppression of 2-deoxy-d-[3H] glucose uptake. Inhibition of the JNK signaling pathway significantly restored glucose uptake despite HCV core expression in hepatocytes. Taken together, HCV core protein increases IRS-1 phosphorylation at Ser312 which may contribute in part to the mechanism of insulin resistance5.
Hepatitis C virus core protein inhibits microsomal triglyceride transfer protein activity and very low density lipoprotein secretion - Liver steatosis, which involves accumulation of intracytoplasmic lipid droplets, is characteristic of hepatitis C virus (HCV) infection. By use of an in vivo transgenic murine model, a study demonstrates that hepatic overexpression of HCV core protein interferes with the hepatic assembly and secretion of triglyceriderich very low density lipoproteins (VLDL). Core expression led to reduction in microsomal triglyceride transfer protein (MTP) activity and in the particle size of nascent hepatic VLDL without affecting accumulation of MTP and protein disulfide isomerase. Hepatic human apolipoprotein AII (apo AII) expression in doublecore/ apo AII transgenic mice diminished intrahepatic core protein accumulation and abrogated its effects on VLDL production. Apo AII and HCV core colocalized in human HCV-infected liver biopsies. This implied that core protein of HCV targets microsomal triglyceride transfer protein activity and modifies hepatic VLDL assembly and secretion6.
References
1.Choo QL, G Kuo, AJ Weiner, LR Overby, DW Bradley, and M Houghton (1989). Isolation of a cDNA clone derived from a blood-borne non-A, non-B viral hepatitis genome. Science, 244:359-362.
2.Grakoui A, McCourt DW, Wychowski C, Feinstone SM, Rice CM (1993). Characterization of the hepatitis C virus-encoded serine proteinase: determination of proteinase-dependent polyprotein cleavage sites. J. Virol, 67(5):2832-2843.
3.Yasui K, Wakita T, Tsukiyama-Kohara K, Funahashi SI, Ichikawa M, Kajita T, Moradpour D, Wands JR, Kohara M (1998).The native form and maturation process of hepatitis C virus core protein. J. Virol, 72(7):6048-55.
4.Liu Q, Tackney C, Bhat RA, Prince AM, Zhang P (1997). Regulated processing of hepatitis C virus core protein is linked to subcellular localization. J. Virol, 71:657-662.
5.Banerjee S, Saito K, Ait-Goughoulte M, Meyer K, Ray RB, Ray R (2008). Hepatitis C Virus Core Protein Upregulates Serine Phosphorylation of Insulin Receptor Substrate-1 and Impairs the Downstream Akt/Protein Kinase B Signaling Pathway for Insulin Resistance. J Virol, 82(6): 2606–2612.
6.Perlemuter G, Sabile A, Letteron, P, Vona, G, Topilco, A, Chre´tien, Y, Koike K, Pessayre D, Chapman J, Barba G, Bre´chot C (2002). Hepatitis C virus core protein inhibits microsomal triglyceride transfer protein activity and very low density lipoprotein secretion: a model of viral-related steatosis. FASEB J, 16(2):185-94.
Hepatitis C virus (HCV) belongs to the genus Hepacivirus in the family Flaviviridae and possesses a viral genome consisting of a single, positive-strand RNA. The genome encodes a large precursor polyprotein of approximately 3,000 amino acids which is processed into at least 10 viral proteins by host and viral proteases.
Discovery
HCV was discovered by Choo et al., 1989 by investigators at Chiron. Portions of the HCV genome were isolated by screening cDNA expression libraries made from RNA and DNA from chimpanzees infected with serum from a patient with post-transfusion non-A, non-B hepatitis. To identify portions of the genome that encoded viral proteins, the libraries were screened with antibodies from patients who had non-A, non-B hepatitis1.
Structural Characteristics
HCV belongs to the genus Hepacivirus in the family Flaviviridae and possesses a viral genome consisting of a single, positive-strand RNA with a nucleotide length of about 9.4 kb. The genome encodes a large precursor polyprotein of approximately 3,000 amino acids. The polyprotein is processed co- and posttranslationally into at least 10 viral proteins by host and viral proteases. The structural proteins of HCV are located in the N-terminal one-fourth of the polyprotein and are cleaved by host membrane proteases2. HCV core protein forms the nucleocapsid, which is surrounded by the envelope containing E1 and E2 glycoproteins3. It has been suggested that HCV core protein is a multifunctional molecule that acts as a structural protein but is also involved in the pathogenesis of hepatitis C. HCV core protein has two major p23 and p21 forms4. HCV core protein p23 represents a 191-amino-acid product in which the C-terminal hydrophobic region also acts as a signal sequence for E1. HCV polyprotein is cleaved between residues 191 and 192 by host signal peptidase to generate C-terminal and N-terminal polypeptides encompassing the core and E1 proteins, respectively. For the full maturation of HCV core protein, the C-terminal signal-anchor sequence was thought to be further processed by an unidentified microsomal protease, and the 21-kDa isoform of core protein is predominantly detected both in cultured cells by transfection with expression plasmid and in viral particles obtained from sera of patients with hepatitis C. These results suggest that p21 is the mature form of HCV core protein3.
Functions
HCV core protein upregulates serine phosphorylation of insulin receptor substrate-1 and impairs the downstream Akt/PKB signaling pathway for insulin resistance - Insulin resistance is a critical component of type 2 diabetes mellitus (T2DM) pathogenesis. Several mechanisms are likely to be involved in the pathogenesis of HCV-related insulin resistance. Since previously it was observed that HCV core protein activates c-Jun N-terminal kinase (JNK) and mitogen-activated protein kinase, a study was conducted to examine the contribution of these pathways to insulin resistance in hepatocytes4. It was found that HCV core protein alone or in the presence of other viral proteins increases Ser312 phosphorylation of the insulin receptor substrate-1 (IRS-1). Hepatocytes infected with cell culture-grown HCV genotype 1a or 2a displayed a significant increase in the Ser473 phosphorylation status of the Ser/Thr kinase protein kinase B (Akt/PKB), while Thr308 phosphorylation was not significantly altered. HCV core protein-mediated Ser312 phosphorylation of IRS-1 was inhibited by JNK (SP600125) and phosphatidylinositol-3 kinase (LY294002) inhibitors. Furthermore, a functional assay also suggested that hepatocytes expressing HCV core protein alone or infected with cell culture-grown HCV exhibited a suppression of 2-deoxy-d-[3H] glucose uptake. Inhibition of the JNK signaling pathway significantly restored glucose uptake despite HCV core expression in hepatocytes. Taken together, HCV core protein increases IRS-1 phosphorylation at Ser312 which may contribute in part to the mechanism of insulin resistance5.
Hepatitis C virus core protein inhibits microsomal triglyceride transfer protein activity and very low density lipoprotein secretion - Liver steatosis, which involves accumulation of intracytoplasmic lipid droplets, is characteristic of hepatitis C virus (HCV) infection. By use of an in vivo transgenic murine model, a study demonstrates that hepatic overexpression of HCV core protein interferes with the hepatic assembly and secretion of triglyceriderich very low density lipoproteins (VLDL). Core expression led to reduction in microsomal triglyceride transfer protein (MTP) activity and in the particle size of nascent hepatic VLDL without affecting accumulation of MTP and protein disulfide isomerase. Hepatic human apolipoprotein AII (apo AII) expression in doublecore/ apo AII transgenic mice diminished intrahepatic core protein accumulation and abrogated its effects on VLDL production. Apo AII and HCV core colocalized in human HCV-infected liver biopsies. This implied that core protein of HCV targets microsomal triglyceride transfer protein activity and modifies hepatic VLDL assembly and secretion6.
References
1.Choo QL, G Kuo, AJ Weiner, LR Overby, DW Bradley, and M Houghton (1989). Isolation of a cDNA clone derived from a blood-borne non-A, non-B viral hepatitis genome. Science, 244:359-362.
2.Grakoui A, McCourt DW, Wychowski C, Feinstone SM, Rice CM (1993). Characterization of the hepatitis C virus-encoded serine proteinase: determination of proteinase-dependent polyprotein cleavage sites. J. Virol, 67(5):2832-2843.
3.Yasui K, Wakita T, Tsukiyama-Kohara K, Funahashi SI, Ichikawa M, Kajita T, Moradpour D, Wands JR, Kohara M (1998).The native form and maturation process of hepatitis C virus core protein. J. Virol, 72(7):6048-55.
4.Liu Q, Tackney C, Bhat RA, Prince AM, Zhang P (1997). Regulated processing of hepatitis C virus core protein is linked to subcellular localization. J. Virol, 71:657-662.
5.Banerjee S, Saito K, Ait-Goughoulte M, Meyer K, Ray RB, Ray R (2008). Hepatitis C Virus Core Protein Upregulates Serine Phosphorylation of Insulin Receptor Substrate-1 and Impairs the Downstream Akt/Protein Kinase B Signaling Pathway for Insulin Resistance. J Virol, 82(6): 2606–2612.
6.Perlemuter G, Sabile A, Letteron, P, Vona, G, Topilco, A, Chre´tien, Y, Koike K, Pessayre D, Chapman J, Barba G, Bre´chot C (2002). Hepatitis C virus core protein inhibits microsomal triglyceride transfer protein activity and very low density lipoprotein secretion: a model of viral-related steatosis. FASEB J, 16(2):185-94.
Gastrin Releasing Peptide (GRP) and Sequences
Definition
Gastrin releasing peptide (GRP) is a 27-amino acid linear neuropeptide, structurally and functionally related to bombesin (BB) that mediates neural release of antral gastrin, causes bronchoconstriction and respiratory tract vasodilation, stimulates growth and mitogenesis of cells in culture, and may act as an excitatory neurotransmitter of enteric interneurons.
Related peptides
The GRP gene encodes a member of the bombesin-like family of gastrin-releasing peptides. Its preproprotein, following cleavage of a signal peptide, is further processed to produce either the 27 aa GRP or the 10 aa neuromedin C1. The GRP and neuromedin B (NMB) are structurally related to BB and exist within the mammalian small intestine. A series of potent GRP antagonists have been developed by modification of the COOH terminus of N-acetyl-GRP-20-27. The most potent member of this series, N-acetyl-GRP-20-26-0CH2CH3, obtained by modification of the COOH-terminal region of this peptide blocks GRP-stimulated mitogenesis, inhibits GRP-dependent release of gastrin and blocks GRP-induced elevation of [Ca2+]i in vitro2.
Discovery
Bombesin is a peptide originally extracted from the skin of the European discoglossid frog Bombina bombino and possessed profound biological potency in mammals. This led to the discovery of the "mammalian bombesins" GRP5 and NMB3. McDonald TJ et al., in 1978 discovered GRP in extracts from porcine non-antral gastric tissue4.
Structural characteristics
Human GRP (hGRP) mRNA encodes a precursor of 148 amino acids containing a typical signal sequence, hGRP consisting of 27 or 28 amino acids, and a carboxyl-terminal extension peptide. hGRP is flanked at its carboxyl terminus by two basic amino acids, following a glycine used for amidation of the carboxyl-terminal methionine. hGRP contains two potential internal tryptic cleavage sites that could generate hGRP-(14-27) or hGRP-(18-27). The two forms of hGRP probably derive from alternative proteolytic processing of pre-proGRP into both GRP-(1-27) and a smaller GRP-like peptide5. While the residues 20-27 of GRP influence binding of the parent peptide to its receptor, the COOH-terminal amino acid is primarily responsible for triggering the subsequent biological response5.
Mode of Action
The effects of GRP are mediated through the GRP receptor. This receptor is a glycosylated, 7-transmembrane G-protein coupled receptor that activates the phospholipase C signaling pathway. The receptor is aberrantly expressed in numerous cancers such as those of the lung, colon, and prostate6.
Functions
GRP is released by the post-ganglionic fibres of the vagus nerve, which innervate the G cells of the stomach and stimulate them to release gastrin. GRP can directly stimulate pepsinogen release from chief cells by a specific GRP receptor that mobilizes intracellular calcium. GRP has a prominent role as a tumor marker in the diagnosis of small-cell lung carcinoma. It regulates numerous functions of the gastrointestinal and central nervous systems, including smooth muscle cell contraction, and epithelial cell proliferation and is a potent mitogen for neoplastic tissues6.
References
1.Chandan R, Newell SM, Brown DR (1988).Actions of gastrin-releasing peptide and related mammalian and amphibian peptides on ion transport in the porcine proximal jejunum. Regul Pept, 23(1):1-14.
2. Heimbrook DC, Saari WS, Balishin NL, Friedman A, Moore KS, Reimen MW, Kiefer DM, Rotberg NS, Wallen JW, Oliff A(1989). Carboxyl-terminal Modification of a Gastrin Releasing Peptide Derivative Generates Potent Antagonists. J Biol Chem, 264(19):11258-11262.
3. Preston SR, Woodhouse LF, Jones-Blackett S, Wyatt JI, Primrose JN(1993). Shaun R. Preston, Linda F. Woodhouse, Steven Jones-Blackett, Judy I. Wyatt, and John N. Primrose.1993. High Affinity Binding Sites for Gastrin Releasing Peptide on Human Gastric Cancer and Menetrier's Mucosa. Cancer Res, 53(21):5090-5092.
4. McDonald TJ, Nilsson G, Vagne M, Ghatei M, Bloom SR, Mutt V.1978. A gastrin releasing peptide from the porcine nonantral gastric tissue. Gut, 19(9):767-774.
5.Spindel ER, Chin WW, Price J, Rees LH, Besser GM, Habener JF(1984). Cloning and characterization of cDNAs encoding human gastrin-releasing peptide. Proc. Nati. Acad. Sci. USA 81(18):5699-5703.
6.Martínez A, Zudaire E, Julián M, Moody TW, Cuttitta F (2005). Gastrin-releasing peptide (GRP) induces angiogenesis and the specific GRP blocker 77427 inhibits tumor growth in vitro and in vivo. Oncogene, 24(25):4106-4113.
Gastrin releasing peptide (GRP) is a 27-amino acid linear neuropeptide, structurally and functionally related to bombesin (BB) that mediates neural release of antral gastrin, causes bronchoconstriction and respiratory tract vasodilation, stimulates growth and mitogenesis of cells in culture, and may act as an excitatory neurotransmitter of enteric interneurons.
Related peptides
The GRP gene encodes a member of the bombesin-like family of gastrin-releasing peptides. Its preproprotein, following cleavage of a signal peptide, is further processed to produce either the 27 aa GRP or the 10 aa neuromedin C1. The GRP and neuromedin B (NMB) are structurally related to BB and exist within the mammalian small intestine. A series of potent GRP antagonists have been developed by modification of the COOH terminus of N-acetyl-GRP-20-27. The most potent member of this series, N-acetyl-GRP-20-26-0CH2CH3, obtained by modification of the COOH-terminal region of this peptide blocks GRP-stimulated mitogenesis, inhibits GRP-dependent release of gastrin and blocks GRP-induced elevation of [Ca2+]i in vitro2.
Discovery
Bombesin is a peptide originally extracted from the skin of the European discoglossid frog Bombina bombino and possessed profound biological potency in mammals. This led to the discovery of the "mammalian bombesins" GRP5 and NMB3. McDonald TJ et al., in 1978 discovered GRP in extracts from porcine non-antral gastric tissue4.
Structural characteristics
Human GRP (hGRP) mRNA encodes a precursor of 148 amino acids containing a typical signal sequence, hGRP consisting of 27 or 28 amino acids, and a carboxyl-terminal extension peptide. hGRP is flanked at its carboxyl terminus by two basic amino acids, following a glycine used for amidation of the carboxyl-terminal methionine. hGRP contains two potential internal tryptic cleavage sites that could generate hGRP-(14-27) or hGRP-(18-27). The two forms of hGRP probably derive from alternative proteolytic processing of pre-proGRP into both GRP-(1-27) and a smaller GRP-like peptide5. While the residues 20-27 of GRP influence binding of the parent peptide to its receptor, the COOH-terminal amino acid is primarily responsible for triggering the subsequent biological response5.
Mode of Action
The effects of GRP are mediated through the GRP receptor. This receptor is a glycosylated, 7-transmembrane G-protein coupled receptor that activates the phospholipase C signaling pathway. The receptor is aberrantly expressed in numerous cancers such as those of the lung, colon, and prostate6.
Functions
GRP is released by the post-ganglionic fibres of the vagus nerve, which innervate the G cells of the stomach and stimulate them to release gastrin. GRP can directly stimulate pepsinogen release from chief cells by a specific GRP receptor that mobilizes intracellular calcium. GRP has a prominent role as a tumor marker in the diagnosis of small-cell lung carcinoma. It regulates numerous functions of the gastrointestinal and central nervous systems, including smooth muscle cell contraction, and epithelial cell proliferation and is a potent mitogen for neoplastic tissues6.
References
1.Chandan R, Newell SM, Brown DR (1988).Actions of gastrin-releasing peptide and related mammalian and amphibian peptides on ion transport in the porcine proximal jejunum. Regul Pept, 23(1):1-14.
2. Heimbrook DC, Saari WS, Balishin NL, Friedman A, Moore KS, Reimen MW, Kiefer DM, Rotberg NS, Wallen JW, Oliff A(1989). Carboxyl-terminal Modification of a Gastrin Releasing Peptide Derivative Generates Potent Antagonists. J Biol Chem, 264(19):11258-11262.
3. Preston SR, Woodhouse LF, Jones-Blackett S, Wyatt JI, Primrose JN(1993). Shaun R. Preston, Linda F. Woodhouse, Steven Jones-Blackett, Judy I. Wyatt, and John N. Primrose.1993. High Affinity Binding Sites for Gastrin Releasing Peptide on Human Gastric Cancer and Menetrier's Mucosa. Cancer Res, 53(21):5090-5092.
4. McDonald TJ, Nilsson G, Vagne M, Ghatei M, Bloom SR, Mutt V.1978. A gastrin releasing peptide from the porcine nonantral gastric tissue. Gut, 19(9):767-774.
5.Spindel ER, Chin WW, Price J, Rees LH, Besser GM, Habener JF(1984). Cloning and characterization of cDNAs encoding human gastrin-releasing peptide. Proc. Nati. Acad. Sci. USA 81(18):5699-5703.
6.Martínez A, Zudaire E, Julián M, Moody TW, Cuttitta F (2005). Gastrin-releasing peptide (GRP) induces angiogenesis and the specific GRP blocker 77427 inhibits tumor growth in vitro and in vivo. Oncogene, 24(25):4106-4113.
Gastrin Releasing Peptide (GRP) and Sequences
Definition
Gastrin releasing peptide (GRP) is a 27-amino acid linear neuropeptide, structurally and functionally related to bombesin (BB) that mediates neural release of antral gastrin, causes bronchoconstriction and respiratory tract vasodilation, stimulates growth and mitogenesis of cells in culture, and may act as an excitatory neurotransmitter of enteric interneurons.
Related peptides
The GRP gene encodes a member of the bombesin-like family of gastrin-releasing peptides. Its preproprotein, following cleavage of a signal peptide, is further processed to produce either the 27 aa GRP or the 10 aa neuromedin C1. The GRP and neuromedin B (NMB) are structurally related to BB and exist within the mammalian small intestine. A series of potent GRP antagonists have been developed by modification of the COOH terminus of N-acetyl-GRP-20-27. The most potent member of this series, N-acetyl-GRP-20-26-0CH2CH3, obtained by modification of the COOH-terminal region of this peptide blocks GRP-stimulated mitogenesis, inhibits GRP-dependent release of gastrin and blocks GRP-induced elevation of [Ca2+]i in vitro2.
Discovery
Bombesin is a peptide originally extracted from the skin of the European discoglossid frog Bombina bombino and possessed profound biological potency in mammals. This led to the discovery of the "mammalian bombesins" GRP5 and NMB3. McDonald TJ et al., in 1978 discovered GRP in extracts from porcine non-antral gastric tissue4.
Structural characteristics
Human GRP (hGRP) mRNA encodes a precursor of 148 amino acids containing a typical signal sequence, hGRP consisting of 27 or 28 amino acids, and a carboxyl-terminal extension peptide. hGRP is flanked at its carboxyl terminus by two basic amino acids, following a glycine used for amidation of the carboxyl-terminal methionine. hGRP contains two potential internal tryptic cleavage sites that could generate hGRP-(14-27) or hGRP-(18-27). The two forms of hGRP probably derive from alternative proteolytic processing of pre-proGRP into both GRP-(1-27) and a smaller GRP-like peptide5. While the residues 20-27 of GRP influence binding of the parent peptide to its receptor, the COOH-terminal amino acid is primarily responsible for triggering the subsequent biological response5.
Mode of Action
The effects of GRP are mediated through the GRP receptor. This receptor is a glycosylated, 7-transmembrane G-protein coupled receptor that activates the phospholipase C signaling pathway. The receptor is aberrantly expressed in numerous cancers such as those of the lung, colon, and prostate6.
Functions
GRP is released by the post-ganglionic fibres of the vagus nerve, which innervate the G cells of the stomach and stimulate them to release gastrin. GRP can directly stimulate pepsinogen release from chief cells by a specific GRP receptor that mobilizes intracellular calcium. GRP has a prominent role as a tumor marker in the diagnosis of small-cell lung carcinoma. It regulates numerous functions of the gastrointestinal and central nervous systems, including smooth muscle cell contraction, and epithelial cell proliferation and is a potent mitogen for neoplastic tissues6.
References
1.Chandan R, Newell SM, Brown DR (1988).Actions of gastrin-releasing peptide and related mammalian and amphibian peptides on ion transport in the porcine proximal jejunum. Regul Pept, 23(1):1-14.
2. Heimbrook DC, Saari WS, Balishin NL, Friedman A, Moore KS, Reimen MW, Kiefer DM, Rotberg NS, Wallen JW, Oliff A(1989). Carboxyl-terminal Modification of a Gastrin Releasing Peptide Derivative Generates Potent Antagonists. J Biol Chem, 264(19):11258-11262.
3. Preston SR, Woodhouse LF, Jones-Blackett S, Wyatt JI, Primrose JN(1993). Shaun R. Preston, Linda F. Woodhouse, Steven Jones-Blackett, Judy I. Wyatt, and John N. Primrose.1993. High Affinity Binding Sites for Gastrin Releasing Peptide on Human Gastric Cancer and Menetrier's Mucosa. Cancer Res, 53(21):5090-5092.
4. McDonald TJ, Nilsson G, Vagne M, Ghatei M, Bloom SR, Mutt V.1978. A gastrin releasing peptide from the porcine nonantral gastric tissue. Gut, 19(9):767-774.
5.Spindel ER, Chin WW, Price J, Rees LH, Besser GM, Habener JF(1984). Cloning and characterization of cDNAs encoding human gastrin-releasing peptide. Proc. Nati. Acad. Sci. USA 81(18):5699-5703.
6.Martínez A, Zudaire E, Julián M, Moody TW, Cuttitta F (2005). Gastrin-releasing peptide (GRP) induces angiogenesis and the specific GRP blocker 77427 inhibits tumor growth in vitro and in vivo. Oncogene, 24(25):4106-4113.
Gastrin releasing peptide (GRP) is a 27-amino acid linear neuropeptide, structurally and functionally related to bombesin (BB) that mediates neural release of antral gastrin, causes bronchoconstriction and respiratory tract vasodilation, stimulates growth and mitogenesis of cells in culture, and may act as an excitatory neurotransmitter of enteric interneurons.
Related peptides
The GRP gene encodes a member of the bombesin-like family of gastrin-releasing peptides. Its preproprotein, following cleavage of a signal peptide, is further processed to produce either the 27 aa GRP or the 10 aa neuromedin C1. The GRP and neuromedin B (NMB) are structurally related to BB and exist within the mammalian small intestine. A series of potent GRP antagonists have been developed by modification of the COOH terminus of N-acetyl-GRP-20-27. The most potent member of this series, N-acetyl-GRP-20-26-0CH2CH3, obtained by modification of the COOH-terminal region of this peptide blocks GRP-stimulated mitogenesis, inhibits GRP-dependent release of gastrin and blocks GRP-induced elevation of [Ca2+]i in vitro2.
Discovery
Bombesin is a peptide originally extracted from the skin of the European discoglossid frog Bombina bombino and possessed profound biological potency in mammals. This led to the discovery of the "mammalian bombesins" GRP5 and NMB3. McDonald TJ et al., in 1978 discovered GRP in extracts from porcine non-antral gastric tissue4.
Structural characteristics
Human GRP (hGRP) mRNA encodes a precursor of 148 amino acids containing a typical signal sequence, hGRP consisting of 27 or 28 amino acids, and a carboxyl-terminal extension peptide. hGRP is flanked at its carboxyl terminus by two basic amino acids, following a glycine used for amidation of the carboxyl-terminal methionine. hGRP contains two potential internal tryptic cleavage sites that could generate hGRP-(14-27) or hGRP-(18-27). The two forms of hGRP probably derive from alternative proteolytic processing of pre-proGRP into both GRP-(1-27) and a smaller GRP-like peptide5. While the residues 20-27 of GRP influence binding of the parent peptide to its receptor, the COOH-terminal amino acid is primarily responsible for triggering the subsequent biological response5.
Mode of Action
The effects of GRP are mediated through the GRP receptor. This receptor is a glycosylated, 7-transmembrane G-protein coupled receptor that activates the phospholipase C signaling pathway. The receptor is aberrantly expressed in numerous cancers such as those of the lung, colon, and prostate6.
Functions
GRP is released by the post-ganglionic fibres of the vagus nerve, which innervate the G cells of the stomach and stimulate them to release gastrin. GRP can directly stimulate pepsinogen release from chief cells by a specific GRP receptor that mobilizes intracellular calcium. GRP has a prominent role as a tumor marker in the diagnosis of small-cell lung carcinoma. It regulates numerous functions of the gastrointestinal and central nervous systems, including smooth muscle cell contraction, and epithelial cell proliferation and is a potent mitogen for neoplastic tissues6.
References
1.Chandan R, Newell SM, Brown DR (1988).Actions of gastrin-releasing peptide and related mammalian and amphibian peptides on ion transport in the porcine proximal jejunum. Regul Pept, 23(1):1-14.
2. Heimbrook DC, Saari WS, Balishin NL, Friedman A, Moore KS, Reimen MW, Kiefer DM, Rotberg NS, Wallen JW, Oliff A(1989). Carboxyl-terminal Modification of a Gastrin Releasing Peptide Derivative Generates Potent Antagonists. J Biol Chem, 264(19):11258-11262.
3. Preston SR, Woodhouse LF, Jones-Blackett S, Wyatt JI, Primrose JN(1993). Shaun R. Preston, Linda F. Woodhouse, Steven Jones-Blackett, Judy I. Wyatt, and John N. Primrose.1993. High Affinity Binding Sites for Gastrin Releasing Peptide on Human Gastric Cancer and Menetrier's Mucosa. Cancer Res, 53(21):5090-5092.
4. McDonald TJ, Nilsson G, Vagne M, Ghatei M, Bloom SR, Mutt V.1978. A gastrin releasing peptide from the porcine nonantral gastric tissue. Gut, 19(9):767-774.
5.Spindel ER, Chin WW, Price J, Rees LH, Besser GM, Habener JF(1984). Cloning and characterization of cDNAs encoding human gastrin-releasing peptide. Proc. Nati. Acad. Sci. USA 81(18):5699-5703.
6.Martínez A, Zudaire E, Julián M, Moody TW, Cuttitta F (2005). Gastrin-releasing peptide (GRP) induces angiogenesis and the specific GRP blocker 77427 inhibits tumor growth in vitro and in vivo. Oncogene, 24(25):4106-4113.
GM-CSF Inhibitory Peptides
Definition
GM-CSF inhibitory peptides are short peptides based on the sequence of human granulocyte macrophage-colony stimulating factor (GM-CSF) exhibited inhibition of GM-CSF binding and direct biological antagonist activity.
Discovery
Linear peptide analogs of GM-CSF were produced by dividing the human GM-CSF sequence into six peptides. This strategy led to the identification of two peptides with receptor binding and antagonist activity by VonFeldt, JM et al., in 19951. One peptide corresponding to residues 17-31 (the A helix of GM-CSF) inhibited high affinity receptor binding, while a second peptide corresponding to residues 54-78 (the B and C helices of GM-CSF) inhibited low affinity receptor binding. This implicates these sites in intermolecular interactions with the GM-CSFR2.
Structural Characteristics
GM-CSF inhibitory peptides are generally derivatives of GM-CSF with amino residue 21 substituted by a basic amino acid. Preferably, the basic amino acid residue is Arg or Lys. The most preferred antagonist comprises Arg at position 21 of GM-CSF and is referred to herein as E21R.
Mostly GM-CSF antagonists are
(i) in unglycosylated form;
(ii) lack post-translational modification;
(iii) produced in prokaryotic microorganisms; and/or
(iv) produced by chemical synthesis.
GM-CSF antagonists carrying a substitution of amino acid 21 (Glu) of human GM-CSF by Arg or Lys are designated "E21R" and "E21K", respectively, based on a single letter designation of the amino acids involved in the substitution and the position of the substitution3.
Two cyclic peptide GM-CSF mimics (1785 and 1786) were designed from structural analysis of the GM-CSF region mimicked by rAb 23.2. The cyclized peptides specifically bind to polyclonal anti-GM-CSF antibody (stronger for 1786 than for 1785). 1786 competes with GM-CSF for binding to the GM-CSF receptor present on HL-60 cells and reverses GM-CSF's prevention of apoptosis of MO7E cells. Thus, 1786 represents a structurally designed biological and receptor antagonist of GM-CSF. Important residues in the GM-CSF structure mimicked by similar residues on 23.2 are postulated to be: Thr-57, Glu-60, Lys-63, Lys-74, Thr-78, Ser-82, and Lys-854.
Mode of Action
The GM-CSF antagonist either blocks the action of wild-type GM-CSF by interacting selectively with the receptor a-chain or induces apoptosis by interacting with the a- and ß-chains of the receptor in a manner that leads to abnormal stimulation of the ß-chain either qualitatively or quantitatively .GM-CSF antagonist E21R binds to the GM-CSF-specific a-chain of the GM-CSF receptor and that such binding directly induces apoptosis of normal and malignant myeloid cells expressing the GM-CSF receptor. 1786 competes with GM-CSF for binding to the GM-CSF receptor4.
Functions
E21R acts as a specific GM-CSF receptor antagonist on human leukemic cells and neutrophils. E21R significantly accelerated apoptosis of eosinophils. The effect of E21R on eosinophil survival was selectively mediated through the GM-CSF receptor complex and not by nonspecific toxicity. The introduction of the GM-CSF analogue E21R may offer a novel therapy in inflammatory diseases associated with eosinophil infiltration of different etiologies5. E21R and E21K are effective antagonists of both nonglycosylated and glycosylated wild-type GM-CSF and have potential clinical significance for the management of inflammatory diseases and certain leukemias where GM-CSF plays a pathogenic role6. Antagonists of GM-CSF are disclosed that comprise antibodies and anti-idiotypic antibodies specific for the carboxyl terminus of GM-CSF. These antagonists are useful for treating various diseases, the symptoms of which are increased by GM-CSF, and for lessening the effects of chemotherapy7.
References
1.VonFeldt JM, Monfardini C, Fish S, Rosenbaum H, Kieber-Emmons T, Williams RM, Khan SA, Weiner DB, Williams WV (1995). Development of GM-CSF antagonist peptides. Pept Res., 8(1):20-27, 30-32.
2.Monfardini C, Kieber-Emmons T, VonFeldt JM, O'Malley B, Rosenbaum H, Godillot AP, Kaushansky K, Brown CB, Voet D, McCallus DE (1995) Recombinant Antibodies in Bioactive Peptide Design. J Biol Chem., 270(12):6628-6638.
3.http://www.patentstorm.us/patents/6322791/description.html
4.Monfardini C, Kieber-Emmons T, Voet D, Godillot AP, Weiner DB, Williams WV (1996). Rational Design of Granulocyte-Macrophage Colony-stimulating Factor Antagonist Peptides. J. Biol. Chem., 271(6):2966-71.
5.Iversen PO, Robinson D, Ying S, Meng Q, Kay AB, Clark-Lewis I, Lopez AF (1997). The GM-CSF Analogue E21R Induces Apoptosis of Normal and Activated Eosinophils. Am. J. Respir. Crit. Care Med, 156(5):1628-1632.
6.Hercus TR, Bagley CJ, Cambareri B, Dottore M, Woodcock JM, Vadas MA, Shannon MF, Lopez AF(1994). Specific human granulocyte-macrophage colony-stimulating factor antagonists. PNAS, 91(13):5838-5842.
GM-CSF inhibitory peptides are short peptides based on the sequence of human granulocyte macrophage-colony stimulating factor (GM-CSF) exhibited inhibition of GM-CSF binding and direct biological antagonist activity.
Discovery
Linear peptide analogs of GM-CSF were produced by dividing the human GM-CSF sequence into six peptides. This strategy led to the identification of two peptides with receptor binding and antagonist activity by VonFeldt, JM et al., in 19951. One peptide corresponding to residues 17-31 (the A helix of GM-CSF) inhibited high affinity receptor binding, while a second peptide corresponding to residues 54-78 (the B and C helices of GM-CSF) inhibited low affinity receptor binding. This implicates these sites in intermolecular interactions with the GM-CSFR2.
Structural Characteristics
GM-CSF inhibitory peptides are generally derivatives of GM-CSF with amino residue 21 substituted by a basic amino acid. Preferably, the basic amino acid residue is Arg or Lys. The most preferred antagonist comprises Arg at position 21 of GM-CSF and is referred to herein as E21R.
Mostly GM-CSF antagonists are
(i) in unglycosylated form;
(ii) lack post-translational modification;
(iii) produced in prokaryotic microorganisms; and/or
(iv) produced by chemical synthesis.
GM-CSF antagonists carrying a substitution of amino acid 21 (Glu) of human GM-CSF by Arg or Lys are designated "E21R" and "E21K", respectively, based on a single letter designation of the amino acids involved in the substitution and the position of the substitution3.
Two cyclic peptide GM-CSF mimics (1785 and 1786) were designed from structural analysis of the GM-CSF region mimicked by rAb 23.2. The cyclized peptides specifically bind to polyclonal anti-GM-CSF antibody (stronger for 1786 than for 1785). 1786 competes with GM-CSF for binding to the GM-CSF receptor present on HL-60 cells and reverses GM-CSF's prevention of apoptosis of MO7E cells. Thus, 1786 represents a structurally designed biological and receptor antagonist of GM-CSF. Important residues in the GM-CSF structure mimicked by similar residues on 23.2 are postulated to be: Thr-57, Glu-60, Lys-63, Lys-74, Thr-78, Ser-82, and Lys-854.
Mode of Action
The GM-CSF antagonist either blocks the action of wild-type GM-CSF by interacting selectively with the receptor a-chain or induces apoptosis by interacting with the a- and ß-chains of the receptor in a manner that leads to abnormal stimulation of the ß-chain either qualitatively or quantitatively .GM-CSF antagonist E21R binds to the GM-CSF-specific a-chain of the GM-CSF receptor and that such binding directly induces apoptosis of normal and malignant myeloid cells expressing the GM-CSF receptor. 1786 competes with GM-CSF for binding to the GM-CSF receptor4.
Functions
E21R acts as a specific GM-CSF receptor antagonist on human leukemic cells and neutrophils. E21R significantly accelerated apoptosis of eosinophils. The effect of E21R on eosinophil survival was selectively mediated through the GM-CSF receptor complex and not by nonspecific toxicity. The introduction of the GM-CSF analogue E21R may offer a novel therapy in inflammatory diseases associated with eosinophil infiltration of different etiologies5. E21R and E21K are effective antagonists of both nonglycosylated and glycosylated wild-type GM-CSF and have potential clinical significance for the management of inflammatory diseases and certain leukemias where GM-CSF plays a pathogenic role6. Antagonists of GM-CSF are disclosed that comprise antibodies and anti-idiotypic antibodies specific for the carboxyl terminus of GM-CSF. These antagonists are useful for treating various diseases, the symptoms of which are increased by GM-CSF, and for lessening the effects of chemotherapy7.
References
1.VonFeldt JM, Monfardini C, Fish S, Rosenbaum H, Kieber-Emmons T, Williams RM, Khan SA, Weiner DB, Williams WV (1995). Development of GM-CSF antagonist peptides. Pept Res., 8(1):20-27, 30-32.
2.Monfardini C, Kieber-Emmons T, VonFeldt JM, O'Malley B, Rosenbaum H, Godillot AP, Kaushansky K, Brown CB, Voet D, McCallus DE (1995) Recombinant Antibodies in Bioactive Peptide Design. J Biol Chem., 270(12):6628-6638.
3.http://www.patentstorm.us/patents/6322791/description.html
4.Monfardini C, Kieber-Emmons T, Voet D, Godillot AP, Weiner DB, Williams WV (1996). Rational Design of Granulocyte-Macrophage Colony-stimulating Factor Antagonist Peptides. J. Biol. Chem., 271(6):2966-71.
5.Iversen PO, Robinson D, Ying S, Meng Q, Kay AB, Clark-Lewis I, Lopez AF (1997). The GM-CSF Analogue E21R Induces Apoptosis of Normal and Activated Eosinophils. Am. J. Respir. Crit. Care Med, 156(5):1628-1632.
6.Hercus TR, Bagley CJ, Cambareri B, Dottore M, Woodcock JM, Vadas MA, Shannon MF, Lopez AF(1994). Specific human granulocyte-macrophage colony-stimulating factor antagonists. PNAS, 91(13):5838-5842.
Glycosylation Test Peptides
Discovery
The glycosylation test peptide, Bz-Asn-Gly-Thr-NH2 was first used by Angela Dieckmann-Schuppert et al., to elucidate the mode and extent of protein glycosylation in P. falciparum1.
Structural characteristics
Commercially available glycosylation test peptides:
Bz-Asn-Gly-Thr-NH2 ( Mr: 393.40)
Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 (Mr: 795.81)
These peptides contain the consensus sequence Asn-X-Thr, known as a potential asparagine glycosylation site2.
Mode of action
Sugars destined to be utilized in protein glycosylation must first be activated by conversion to their nucleotide derivatives prior to eventually being attached to dolichol-(pyro)phosphate or to being directly incorporated into glycans. Oligosaccharyl-transferase activity is then determined by incubating DolPP-oligosaccharide and peptide (N -benzoyl-Asn-Gly-Thr-NH2) in the presence of enzyme and reagents. The test peptide undergoes glycosylation and the nature of the (O- or N-) glycosylation reaction is analysed based on the glycosylated product1.
Functions
Bz-Asn-Gly-Thr-NH2 is used to study the N-glycosylation activity of cell lysates. Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 has been used to probe the N-glycosylation activity of cell lysates of Trypanosoma gondii and Trypanosoma brucei brucei2.
References
1.Dieckmann-Schuppert A, Bender S, Odenthal-Schnittler M, Bause E, Schwarz RT (1992). Apparent lack of N-glycosylation in the asexual intraerythrocytic stage of Plasmodium falciparum. Eur. J. Biochem. 205(2):815-825.
2.Dieckmann-Schuppert A, Bause E, Schwarz RT (1994). Glycosylation reactions in Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma brucei brucei probed by the use of synthetic peptides. Biochim Biophys Acta. 1199(1):37-44.
The glycosylation test peptide, Bz-Asn-Gly-Thr-NH2 was first used by Angela Dieckmann-Schuppert et al., to elucidate the mode and extent of protein glycosylation in P. falciparum1.
Structural characteristics
Commercially available glycosylation test peptides:
Bz-Asn-Gly-Thr-NH2 ( Mr: 393.40)
Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 (Mr: 795.81)
These peptides contain the consensus sequence Asn-X-Thr, known as a potential asparagine glycosylation site2.
Mode of action
Sugars destined to be utilized in protein glycosylation must first be activated by conversion to their nucleotide derivatives prior to eventually being attached to dolichol-(pyro)phosphate or to being directly incorporated into glycans. Oligosaccharyl-transferase activity is then determined by incubating DolPP-oligosaccharide and peptide (N -benzoyl-Asn-Gly-Thr-NH2) in the presence of enzyme and reagents. The test peptide undergoes glycosylation and the nature of the (O- or N-) glycosylation reaction is analysed based on the glycosylated product1.
Functions
Bz-Asn-Gly-Thr-NH2 is used to study the N-glycosylation activity of cell lysates. Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 has been used to probe the N-glycosylation activity of cell lysates of Trypanosoma gondii and Trypanosoma brucei brucei2.
References
1.Dieckmann-Schuppert A, Bender S, Odenthal-Schnittler M, Bause E, Schwarz RT (1992). Apparent lack of N-glycosylation in the asexual intraerythrocytic stage of Plasmodium falciparum. Eur. J. Biochem. 205(2):815-825.
2.Dieckmann-Schuppert A, Bause E, Schwarz RT (1994). Glycosylation reactions in Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma brucei brucei probed by the use of synthetic peptides. Biochim Biophys Acta. 1199(1):37-44.
Glycosylation Test Peptides
Discovery
The glycosylation test peptide, Bz-Asn-Gly-Thr-NH2 was first used by Angela Dieckmann-Schuppert et al., to elucidate the mode and extent of protein glycosylation in P. falciparum1.
Structural characteristics
Commercially available glycosylation test peptides:
Bz-Asn-Gly-Thr-NH2 ( Mr: 393.40)
Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 (Mr: 795.81)
These peptides contain the consensus sequence Asn-X-Thr, known as a potential asparagine glycosylation site2.
Mode of action
Sugars destined to be utilized in protein glycosylation must first be activated by conversion to their nucleotide derivatives prior to eventually being attached to dolichol-(pyro)phosphate or to being directly incorporated into glycans. Oligosaccharyl-transferase activity is then determined by incubating DolPP-oligosaccharide and peptide (N -benzoyl-Asn-Gly-Thr-NH2) in the presence of enzyme and reagents. The test peptide undergoes glycosylation and the nature of the (O- or N-) glycosylation reaction is analysed based on the glycosylated product1.
Functions
Bz-Asn-Gly-Thr-NH2 is used to study the N-glycosylation activity of cell lysates. Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 has been used to probe the N-glycosylation activity of cell lysates of Trypanosoma gondii and Trypanosoma brucei brucei2.
References
1.Dieckmann-Schuppert A, Bender S, Odenthal-Schnittler M, Bause E, Schwarz RT (1992). Apparent lack of N-glycosylation in the asexual intraerythrocytic stage of Plasmodium falciparum. Eur. J. Biochem. 205(2):815-825.
2.Dieckmann-Schuppert A, Bause E, Schwarz RT (1994). Glycosylation reactions in Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma brucei brucei probed by the use of synthetic peptides. Biochim Biophys Acta. 1199(1):37-44.
The glycosylation test peptide, Bz-Asn-Gly-Thr-NH2 was first used by Angela Dieckmann-Schuppert et al., to elucidate the mode and extent of protein glycosylation in P. falciparum1.
Structural characteristics
Commercially available glycosylation test peptides:
Bz-Asn-Gly-Thr-NH2 ( Mr: 393.40)
Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 (Mr: 795.81)
These peptides contain the consensus sequence Asn-X-Thr, known as a potential asparagine glycosylation site2.
Mode of action
Sugars destined to be utilized in protein glycosylation must first be activated by conversion to their nucleotide derivatives prior to eventually being attached to dolichol-(pyro)phosphate or to being directly incorporated into glycans. Oligosaccharyl-transferase activity is then determined by incubating DolPP-oligosaccharide and peptide (N -benzoyl-Asn-Gly-Thr-NH2) in the presence of enzyme and reagents. The test peptide undergoes glycosylation and the nature of the (O- or N-) glycosylation reaction is analysed based on the glycosylated product1.
Functions
Bz-Asn-Gly-Thr-NH2 is used to study the N-glycosylation activity of cell lysates. Dnp-Arg-Asn-Ala-Thr-Ala-Val-NH2 has been used to probe the N-glycosylation activity of cell lysates of Trypanosoma gondii and Trypanosoma brucei brucei2.
References
1.Dieckmann-Schuppert A, Bender S, Odenthal-Schnittler M, Bause E, Schwarz RT (1992). Apparent lack of N-glycosylation in the asexual intraerythrocytic stage of Plasmodium falciparum. Eur. J. Biochem. 205(2):815-825.
2.Dieckmann-Schuppert A, Bause E, Schwarz RT (1994). Glycosylation reactions in Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma brucei brucei probed by the use of synthetic peptides. Biochim Biophys Acta. 1199(1):37-44.
FMRFamide and Analogs
Definition
FMRFamide is a molluscan neuroactive peptide which induces a fast excitatory depolarizing response due to direct activation of amiloride-sensitive sodium channels1.
Related peptides
FLRFamide, LFRFamide, FFRFamide, LLRFamide, D-FMRFamide, are FMRFamide analogs that have been found to exhibit a cross-interaction with FMRFamide. It is possible that these peptides also act on the same class of RFamide receptors as agonists to cause cross desensitization2. Two invertebrate neuropeptide analogues, IPPQFMRF amide (IF-8 amide) and EGDEDEFLRF amide (EF-10 amide), from the defensive skin secretions of two different species of African hyperoliid frogs, Kassina maculata and Phylictimantis verrucosus, respectively, represent the first canonical FMRF amide-related peptides (FaRPs) from a vertebrate source3.
Discovery
The first FMRF-amide was isolated in 1977 as a cardioexcitatory molecule from the clam Macrocallista nimbosa, by DA Price and MJ Greenberg4.
Structural Characteristics
It is a tetrapeptide neurotransmitter, a member of the same family of RFamide peptides as FLRFamide, sharing the same C terminal RFamide sequence. The structure of FMRFamide was first determined by the combined use of Edman dansyl degradation and tryptic digestion and confirmed by synthesis5.
Structure-activity relations (SAR) of FMRFamide on the isolated Rapana heart5 have shown that:
(1) The C-terminal RFamide is critical for activity; potency is markedly diminished by substitution with D amino acids and is abolished upon removal of the amide.
(2) The N-terminal phenylalanine and the methionine could be replaced by other residues, but a total length of at least four residues is important for activity.
(3) N-terminal elongation may have little effect.
(4) FMRFamide was the most potent of 14 peptides tested6.
Mode of Action
It has been reported that FMRFamides exert their effect by directly activating FMRFamide-gated sodium channels without involvement of a G protein. However, earlier electrophysiological studies in molluscs suggested that FMRFamide could also activate a GPCR6.
Functions
FMRFamides act as neurotransmitters/neuromodulators within the larval and adult CNS, as well as at selected peripheral targets. The latter include, for example, tissues associated with feeding (gut, salivary glands), reproduction (accessory glands, spermatheca, and oviducts), movement (skeletal muscle), circulation (aorta), and ecdysis (coordinated modulation of visceral and skeletal muscles) 6.
References
1.Lingueglia E, Champigny G, Lazdunski M, Barbry P (1995). Cloning of the amiloride-sensitive FMRFamide peptide-gated sodium channel. Nature, 378(6558):730-733.
2.Chen ML, Sharma R, Walker RJ (1995). Structure-activity studies of RFamide analogues on central neurones of Helix aspersa. Regulatory peptides,58:99-105.
3.Wang L, Smyth A, Johnsen AH, Zhou M, Chen T, Walker B, Shaw C (2009). FMRFamide-related peptides (FaRPs): A new family of peptides from amphibian defensive skin secretions. BBRC, 383(3):314-319
4.Price DA, Greenberg MJ (1977). Structure of a molluscan cardioexcitatory neuropeptide. Science, 197(4304):670-671.
5.Kobayashi M , Muneoka Y (1989). Functions, Receptors, and Mechanisms of the FMRFamide-Related Peptides. Biol. Bull, 177: 206-209.
6.Meeusen T, Mertens I, Clynen E, Baggerman G, Nichols R, Nachman RJ, Huybrechts R, De Loof A, Schoofs L (2002). Identification in Drosophila melanogaster of the invertebrate G protein-coupled FMRFamide receptor. PNAS, 99(24):15363-15368.
FMRFamide is a molluscan neuroactive peptide which induces a fast excitatory depolarizing response due to direct activation of amiloride-sensitive sodium channels1.
Related peptides
FLRFamide, LFRFamide, FFRFamide, LLRFamide, D-FMRFamide, are FMRFamide analogs that have been found to exhibit a cross-interaction with FMRFamide. It is possible that these peptides also act on the same class of RFamide receptors as agonists to cause cross desensitization2. Two invertebrate neuropeptide analogues, IPPQFMRF amide (IF-8 amide) and EGDEDEFLRF amide (EF-10 amide), from the defensive skin secretions of two different species of African hyperoliid frogs, Kassina maculata and Phylictimantis verrucosus, respectively, represent the first canonical FMRF amide-related peptides (FaRPs) from a vertebrate source3.
Discovery
The first FMRF-amide was isolated in 1977 as a cardioexcitatory molecule from the clam Macrocallista nimbosa, by DA Price and MJ Greenberg4.
Structural Characteristics
It is a tetrapeptide neurotransmitter, a member of the same family of RFamide peptides as FLRFamide, sharing the same C terminal RFamide sequence. The structure of FMRFamide was first determined by the combined use of Edman dansyl degradation and tryptic digestion and confirmed by synthesis5.
Structure-activity relations (SAR) of FMRFamide on the isolated Rapana heart5 have shown that:
(1) The C-terminal RFamide is critical for activity; potency is markedly diminished by substitution with D amino acids and is abolished upon removal of the amide.
(2) The N-terminal phenylalanine and the methionine could be replaced by other residues, but a total length of at least four residues is important for activity.
(3) N-terminal elongation may have little effect.
(4) FMRFamide was the most potent of 14 peptides tested6.
Mode of Action
It has been reported that FMRFamides exert their effect by directly activating FMRFamide-gated sodium channels without involvement of a G protein. However, earlier electrophysiological studies in molluscs suggested that FMRFamide could also activate a GPCR6.
Functions
FMRFamides act as neurotransmitters/neuromodulators within the larval and adult CNS, as well as at selected peripheral targets. The latter include, for example, tissues associated with feeding (gut, salivary glands), reproduction (accessory glands, spermatheca, and oviducts), movement (skeletal muscle), circulation (aorta), and ecdysis (coordinated modulation of visceral and skeletal muscles) 6.
References
1.Lingueglia E, Champigny G, Lazdunski M, Barbry P (1995). Cloning of the amiloride-sensitive FMRFamide peptide-gated sodium channel. Nature, 378(6558):730-733.
2.Chen ML, Sharma R, Walker RJ (1995). Structure-activity studies of RFamide analogues on central neurones of Helix aspersa. Regulatory peptides,58:99-105.
3.Wang L, Smyth A, Johnsen AH, Zhou M, Chen T, Walker B, Shaw C (2009). FMRFamide-related peptides (FaRPs): A new family of peptides from amphibian defensive skin secretions. BBRC, 383(3):314-319
4.Price DA, Greenberg MJ (1977). Structure of a molluscan cardioexcitatory neuropeptide. Science, 197(4304):670-671.
5.Kobayashi M , Muneoka Y (1989). Functions, Receptors, and Mechanisms of the FMRFamide-Related Peptides. Biol. Bull, 177: 206-209.
6.Meeusen T, Mertens I, Clynen E, Baggerman G, Nichols R, Nachman RJ, Huybrechts R, De Loof A, Schoofs L (2002). Identification in Drosophila melanogaster of the invertebrate G protein-coupled FMRFamide receptor. PNAS, 99(24):15363-15368.
Fibronectin Fragments and Analogs
Definition
Proteolytic enzymes, released early in the course of an inflammatory response, hydrolyze fibronectin, producing fragments of the parent molecule that alter monocyte phenotype and migratory behavior1.
Related peptides
Two analogs of fibronectin, mimicking the 1977-1991 C- terminal part of fibronectin have been synthesized and tested. AWLI stimulated human fibronectin fragment 1977-1991, whereas AWLII hybridized to both RGD and 1977-1991 fragments2. A novel peptide sequence derived from the 33/66 kD fragments of fibronectin, FN-C/H-V (WQPPRARI), directly promotes the adhesion, spreading, and migration of rabbit corneal epithelial cells. A second peptide from the 33/66 kD fragments of fibronectin, FN-C/H-IV (SPPRRARVT), promotes rabbit corneal epithelial cell adhesion and spreading3.
Discovery
In 1973, Richard Hynes reported the discovery of an unknown structural protein positioned on the surface of normal cells, but which was rare or conspicuously absent on tumor cells. By the mid 1970s, Vaheri and colleagues named this protein, fibronectin (joining the Latin fibra, meaning fiber, and nectere, meaning to bind or connect). A decade after the discovery of fibronectin, Erkki Ruoslahti and colleagues identified the three-amino-acid consensus sequence that is necessary for fibronectin to attach to cells. The tripeptide, called RGD. Jacqueline Labat-Robert, M.D., a scientist at the University of Paris, suggested the fragmentation of fibronectin by proteases into smaller, free-floating fragments that possess altered chemical qualities and which are "a frequent phenomenon" of a number of pathological states, including potentially cancer 4.
Structural Characteristics
Fibronectin is a mosaic protein consisting of repeating sequence elements or 'modules' that are capable of folding independently (Bork et al., 1996). Its primary sequence is composed almost entirely of three types of module (F1, F2 and F3), which are organized into functional domains. These domains may be isolated in the form of proteolytic fragments that retain affinity for various ligands. Consequently, many of the ligand-binding sites have been mapped to specific regions of the fibronectin polypeptide5. 30-kDa, 50-kDa and 70-kDa gelatin-binding, 60-kDa central and 60–65-kDa heparin-binding fragments were produced by trypsin digestion of fibronectin. The secondary structure of the fragments was studied by circular dichroism and quantitative infrared spectroscopy. The structure of the 70-kDa gelatin-binding, 60-kDa central and 60–65-kDa heparin-binding fragments in solution appeared to be very close to that in the intact fibronectin. The content of the antiparallel ß-form, the only element of the secondary structure in all the fragments studied, was shown to be 30–35%6.
Mode of Action
120-kDa cell-binding FN fragments (FN120) decreases VLA-5 (monocyte fibronectin (FN) receptor) expression by inducing a serine proteinase-dependent proteolysis of this beta(1) integrin. Changes in VLA-5 expression, which were induced by interactions with cell-binding FN fragments, may alter monocyte migration into tissue FN, a prominent component of the cardiac extracellular matrix7.
The 180-kDa. fibronectin fragment both directly opsonizes particulate activators and interacts with monocyte fibronectin receptors to promote particle adherence, thereby enhancing phagocytosis through a concerted action with the distinct receptors for particulate activators8.
A 40 kDa carboxyl (COOH)-terminal heparin-binding fibronectin fragment containing both the III12-14 and IIICS domains (HBFN-f) can stimulate production of matrix metalloproteinases (MMPs) in normal articular cartilage explant cultures. COOH-terminal heparin-binding domain in HBFN-f is known to bind CD44, a principal hyaluronan receptor. The MMP induction by HBFN-f involves CD44 and a specific heparin-binding amino acid sequence (WQPPRARI) in HBFN-f in human normal articular cartilage. CD44 is up-regulated in articular cartilage from patients with OA [Osteoarthritis] and RA [Rheumatoid arthritis]. Increased fibronectin fragments are thought to be involved in cartilage destruction in OA and RA through their catabolic effects9.
Functions
Fibronectin fragments regulate the ability of monocytes to migrate through injured tissue. Evidence that FNf also induce monocyte-derived macrophages to produce agents that protect parenchymal cells against apoptosis expands its homeostatic role and indicates that, even at the outset, host responses to tissue injury may produce agents that help to limit that injury1. Fragments that bind to collagen have been isolated and have been shown to be different from those that mediate cell attachment. Heparin-binding fragments that possess neither the collagen-binding nor cell attachment functions have also been described. The binding sites for Staphylococci and fibrinogen have been located in yet another fragment at the NH2-terminal end of the molecule. The actin-binding site is located close to the collagen-binding site. The remaining active sites are known to be located in the COOH-terminal two-thirds of the polypeptide. The 200K fraction and the 170K, 100K, and 80K fragments have the same NH2-terminal sequences. They also all contain the binding site for collagen known to be located near the NH2 terminus of the fibronectin polypeptide. These results indicate that the NH2 termini of these fragments originate from the same peptide bond in the fibronectin polypeptide and extend different lengths toward the COOH-terminal end. The l00K and 80K fragments only bind to gelatin, the 170K fragment mediates cell attachment, but does not bind to heparin, while all three activities were present in the 200K fraction. The increasing number of activities in the larger fractions is not based on the large size alone, but seems to depend on the presence of distinct binding sites. The Mr = 30,000 to 50,000 heparin-binding fragments that have recently been isolated may have originated from the portion that contains the heparin-binding area in the 205K and 190K fragments. Moreover, the cell attachment-promoting activity can be separated from the gelatin-binding and heparin-binding activities, supporting the idea that a distinct binding site occupying a defined stretch of the polypeptide is also involved in this activity10.
References
1.Trial J, Rossen RD, Rubio J, Knowlton AA(2004). Inflammation and Ischemia: Macrophages Activated by Fibronectin Fragments Enhance the Survival of Injured Cardiac Myocytes. Exp. Biol. and Med., 229(6):538-545.
2.Szaniawska B, Trembacz H, Miloszewska J, Lipkowski AW, Misicka A, Ostrowski J, Janik P(2001). Peptide analog of fibronectin that inhibits cell migration and ERK 1/2 activity. Peptides, 22(12):1949-1953.
3.Mooradian DL, McCarthy JB, Skubitz AP, Cameron JD, Furcht LT(1993). Characterization of FN-C/H-V, a novel synthetic peptide from fibronectin that promotes rabbit corneal epithelial cell adhesion, spreading, and motility. Invest Ophthalmol Vis Sci, 34(1):153-164
4.Longtin R (2004). Birthday of a Breakthrough: Fibronectin Research Proves Important, But Not As Originally Expected. J Natl Cancer Inst, 96(4):254-255.
5.Pickford AR, Smith SP, Staunton D, Boyd J, Campbell ID (2001). The hairpin structure of the 6F11F22F2 fragment from human fibronectin enhances gelatin binding. The EMBO Journal, 20(7):1519-1529.
6.Venyaminov SYu, Metsis ML, Chernousov MA, Koteliansky VE(1983). Distribution of secondary structure along the fibronectin molecule. Eur. J. Biochem, 135(3):485-489.
7.Trial J, Baughn RE, Wygant JN, McIntyre BW, Birdsall HH, Youker KA, Evans A, Entman ML, Rossen RD(1999). Fibronectin fragments modulate monocyte VLA-5 expression and monocyte migration. J Clin Invest, 104(4):419-430.
8.Czop JK, Austen KF(1982). Augmentation of phagocytosis by a specific fibronectin fragment that links particulate activators to the fibronectin adherence receptor of human monocytes. J Immunol., 129(6):2678-2681.
9.Yasuda T, Kakinuma T, Julovi SM, Yoshida M, Hiramitsu T, Akiyoshi M, Nakamura T(2004). COOH-terminal heparin-binding fibronectin fragment induces nitric oxide production in rheumatoid cartilage through CD44. Rheumatology, 43(9):1116-1120.
10.Ruoslahti E, Hayman EG, Engvall E, Cothran WC, Butler WT(1981). Alignment of Biologically Active Domains in the Fibronectin Molecule. J Biol. Chem., 256(14):7277-7281.
Proteolytic enzymes, released early in the course of an inflammatory response, hydrolyze fibronectin, producing fragments of the parent molecule that alter monocyte phenotype and migratory behavior1.
Related peptides
Two analogs of fibronectin, mimicking the 1977-1991 C- terminal part of fibronectin have been synthesized and tested. AWLI stimulated human fibronectin fragment 1977-1991, whereas AWLII hybridized to both RGD and 1977-1991 fragments2. A novel peptide sequence derived from the 33/66 kD fragments of fibronectin, FN-C/H-V (WQPPRARI), directly promotes the adhesion, spreading, and migration of rabbit corneal epithelial cells. A second peptide from the 33/66 kD fragments of fibronectin, FN-C/H-IV (SPPRRARVT), promotes rabbit corneal epithelial cell adhesion and spreading3.
Discovery
In 1973, Richard Hynes reported the discovery of an unknown structural protein positioned on the surface of normal cells, but which was rare or conspicuously absent on tumor cells. By the mid 1970s, Vaheri and colleagues named this protein, fibronectin (joining the Latin fibra, meaning fiber, and nectere, meaning to bind or connect). A decade after the discovery of fibronectin, Erkki Ruoslahti and colleagues identified the three-amino-acid consensus sequence that is necessary for fibronectin to attach to cells. The tripeptide, called RGD. Jacqueline Labat-Robert, M.D., a scientist at the University of Paris, suggested the fragmentation of fibronectin by proteases into smaller, free-floating fragments that possess altered chemical qualities and which are "a frequent phenomenon" of a number of pathological states, including potentially cancer 4.
Structural Characteristics
Fibronectin is a mosaic protein consisting of repeating sequence elements or 'modules' that are capable of folding independently (Bork et al., 1996). Its primary sequence is composed almost entirely of three types of module (F1, F2 and F3), which are organized into functional domains. These domains may be isolated in the form of proteolytic fragments that retain affinity for various ligands. Consequently, many of the ligand-binding sites have been mapped to specific regions of the fibronectin polypeptide5. 30-kDa, 50-kDa and 70-kDa gelatin-binding, 60-kDa central and 60–65-kDa heparin-binding fragments were produced by trypsin digestion of fibronectin. The secondary structure of the fragments was studied by circular dichroism and quantitative infrared spectroscopy. The structure of the 70-kDa gelatin-binding, 60-kDa central and 60–65-kDa heparin-binding fragments in solution appeared to be very close to that in the intact fibronectin. The content of the antiparallel ß-form, the only element of the secondary structure in all the fragments studied, was shown to be 30–35%6.
Mode of Action
120-kDa cell-binding FN fragments (FN120) decreases VLA-5 (monocyte fibronectin (FN) receptor) expression by inducing a serine proteinase-dependent proteolysis of this beta(1) integrin. Changes in VLA-5 expression, which were induced by interactions with cell-binding FN fragments, may alter monocyte migration into tissue FN, a prominent component of the cardiac extracellular matrix7.
The 180-kDa. fibronectin fragment both directly opsonizes particulate activators and interacts with monocyte fibronectin receptors to promote particle adherence, thereby enhancing phagocytosis through a concerted action with the distinct receptors for particulate activators8.
A 40 kDa carboxyl (COOH)-terminal heparin-binding fibronectin fragment containing both the III12-14 and IIICS domains (HBFN-f) can stimulate production of matrix metalloproteinases (MMPs) in normal articular cartilage explant cultures. COOH-terminal heparin-binding domain in HBFN-f is known to bind CD44, a principal hyaluronan receptor. The MMP induction by HBFN-f involves CD44 and a specific heparin-binding amino acid sequence (WQPPRARI) in HBFN-f in human normal articular cartilage. CD44 is up-regulated in articular cartilage from patients with OA [Osteoarthritis] and RA [Rheumatoid arthritis]. Increased fibronectin fragments are thought to be involved in cartilage destruction in OA and RA through their catabolic effects9.
Functions
Fibronectin fragments regulate the ability of monocytes to migrate through injured tissue. Evidence that FNf also induce monocyte-derived macrophages to produce agents that protect parenchymal cells against apoptosis expands its homeostatic role and indicates that, even at the outset, host responses to tissue injury may produce agents that help to limit that injury1. Fragments that bind to collagen have been isolated and have been shown to be different from those that mediate cell attachment. Heparin-binding fragments that possess neither the collagen-binding nor cell attachment functions have also been described. The binding sites for Staphylococci and fibrinogen have been located in yet another fragment at the NH2-terminal end of the molecule. The actin-binding site is located close to the collagen-binding site. The remaining active sites are known to be located in the COOH-terminal two-thirds of the polypeptide. The 200K fraction and the 170K, 100K, and 80K fragments have the same NH2-terminal sequences. They also all contain the binding site for collagen known to be located near the NH2 terminus of the fibronectin polypeptide. These results indicate that the NH2 termini of these fragments originate from the same peptide bond in the fibronectin polypeptide and extend different lengths toward the COOH-terminal end. The l00K and 80K fragments only bind to gelatin, the 170K fragment mediates cell attachment, but does not bind to heparin, while all three activities were present in the 200K fraction. The increasing number of activities in the larger fractions is not based on the large size alone, but seems to depend on the presence of distinct binding sites. The Mr = 30,000 to 50,000 heparin-binding fragments that have recently been isolated may have originated from the portion that contains the heparin-binding area in the 205K and 190K fragments. Moreover, the cell attachment-promoting activity can be separated from the gelatin-binding and heparin-binding activities, supporting the idea that a distinct binding site occupying a defined stretch of the polypeptide is also involved in this activity10.
References
1.Trial J, Rossen RD, Rubio J, Knowlton AA(2004). Inflammation and Ischemia: Macrophages Activated by Fibronectin Fragments Enhance the Survival of Injured Cardiac Myocytes. Exp. Biol. and Med., 229(6):538-545.
2.Szaniawska B, Trembacz H, Miloszewska J, Lipkowski AW, Misicka A, Ostrowski J, Janik P(2001). Peptide analog of fibronectin that inhibits cell migration and ERK 1/2 activity. Peptides, 22(12):1949-1953.
3.Mooradian DL, McCarthy JB, Skubitz AP, Cameron JD, Furcht LT(1993). Characterization of FN-C/H-V, a novel synthetic peptide from fibronectin that promotes rabbit corneal epithelial cell adhesion, spreading, and motility. Invest Ophthalmol Vis Sci, 34(1):153-164
4.Longtin R (2004). Birthday of a Breakthrough: Fibronectin Research Proves Important, But Not As Originally Expected. J Natl Cancer Inst, 96(4):254-255.
5.Pickford AR, Smith SP, Staunton D, Boyd J, Campbell ID (2001). The hairpin structure of the 6F11F22F2 fragment from human fibronectin enhances gelatin binding. The EMBO Journal, 20(7):1519-1529.
6.Venyaminov SYu, Metsis ML, Chernousov MA, Koteliansky VE(1983). Distribution of secondary structure along the fibronectin molecule. Eur. J. Biochem, 135(3):485-489.
7.Trial J, Baughn RE, Wygant JN, McIntyre BW, Birdsall HH, Youker KA, Evans A, Entman ML, Rossen RD(1999). Fibronectin fragments modulate monocyte VLA-5 expression and monocyte migration. J Clin Invest, 104(4):419-430.
8.Czop JK, Austen KF(1982). Augmentation of phagocytosis by a specific fibronectin fragment that links particulate activators to the fibronectin adherence receptor of human monocytes. J Immunol., 129(6):2678-2681.
9.Yasuda T, Kakinuma T, Julovi SM, Yoshida M, Hiramitsu T, Akiyoshi M, Nakamura T(2004). COOH-terminal heparin-binding fibronectin fragment induces nitric oxide production in rheumatoid cartilage through CD44. Rheumatology, 43(9):1116-1120.
10.Ruoslahti E, Hayman EG, Engvall E, Cothran WC, Butler WT(1981). Alignment of Biologically Active Domains in the Fibronectin Molecule. J Biol. Chem., 256(14):7277-7281.
Fibrinopeptides
Definition
Nonsubstrate interaction of thrombin with fibrinogen promotes sequential cleavage of fibrinopeptides A and B (FPA and FPB, respectively) from the latter, resulting in its conversion into fibrin1.
Related peptides
The three forms of FPA (AP, A, AY) and two forms of FPB (B, des Arg B) have be identified and quantified in biological samples. Amino acid substitutions in these forms are associated with a number of congenital fibrinogen abnormalities2.
Discovery
In 1951, Lorand et al., reported cleavage of fibrinopeptides from fibrinogen during fibrin clot formation3.
Structural Characteristics
Fibrinogen is cleaved by thrombin at Arg16-Gly17 of the Aa chain and at Arg14-Gly15 of them Bß chain, releasing fibrinopeptides A and B, respectively, and exposing new amino terminal ends of the a and ß - chains, and these are involved in polymerization. FPB cleavage and exposure of the p 15-42 region of the fibrin molecule by thrombin is necessary to stimulate spreading of adherent endothelial cells4. The amino acid sequences of human FPA and FPB are reported to be:H - Ala - Asp - Ser - Gly - Glu - Gly - Asp - Phe - Leu - Ala - Glu - Gly - Gly - Gly - Val - Arg – OH, and Pyr - Gly - Val - Asn - Asp - Asn - Glu - Glu - Gly - Phe - Phe - Ser - Ala - Arg - OH, respectively.
Mode of Action
To convert soluble fibrinogen to insoluble fibrin, thrombin cleaves fibrinopeptide A (FpA, A 1-16) to expose the "A" polymerization site. This "A" site noncovalently interacts with the "a" polymerization site in the C domain of another fibrinogen molecule. This A: a interaction results in the spontaneous formation of half-staggered, double-stranded protofibrils. As these protofibrils grow in length, thrombin cleaves FPB (FpB, B 1-14), which exposes the "B" site and dissociates the C domains from the central E nodule. The release of FpB results in an enhanced rate of lateral aggregation of protofibrils to form thick fibers. Lateral aggregation is supported by multiple interactions, including: a specific, noncovalent interaction between the "B" site and the "b" polymerization site in the C domain of another molecule, intermolecular interactions between C domains of different fibrin molecules, and interactions between 2 C domains of different protofibrils, specifically residues 330 to 375. The end result of thrombin-catalyzed polymerization is the formation of a complex branching network of insoluble fibers5.
Functions
Thrombin cleavage of fibrinogen into FPA and FPB is essential for fibrin clot formation. FPA and FPB, cleavage products of the Aa and Bß chains, respectively, have both been reported to cause vasoconstriction6, and FPB is a chemoattractant for neutrophils and fibroblasts at certain concentrations7. Potentiation of fibroblast proliferation by FPA and FPB has also been suggested7, and both peptides have been found to possess mitogenic activity8.
References
1.Pechik I, Yakovlev S, Mosesson MW, Gilliland GL, Medved L (2006). Structural Basis for Sequential Cleavage of Fibrinopeptides upon Fibrin Assembly. Biochemistry, 45(11): 3588–3597.
2.Southan C, Thompson E, Lane DA (1987). Direct analysis of plasma fibrinogen-derived fibrinopeptides by high-performance liquid chromatography: investigation of nine congenital fibrinogen abnormalities. Br journal of Haematology, 65(4):469-473.
3.Lorand L (1951). 'Fibrino-Peptide'; New Aspects of the Fibrinogen–Fibrin Transformation. Nature, 167(4259):992-993.
4.Sporn LA, Bunce LA, Francis CW (1995). Cell proliferation on fibrin: modulation by fibrinopeptide cleavage. Blood, 86(5):1802-1810.
5.Moen JL, Gorkun OV, Weisel JW, Lord ST(2003). Recombinant BßArg14His fibrinogen implies participation of N-terminus of Bßchain in desA fibrin polymerization. Blood, 102(7): 2466-2471.
6.Bayley T, Clements JA, Osbahr AJ (1967). Pulmonary and circulatory effects of fibrinopeptides. Circ Res., 21 (4):469-485.
7.Senior RM, Skogen WF, Griffin GL, Wilner GD(1986). Effects of fibrinogen derivatives upon the inflammatory response. Studies with human fibrinopeptide B. J Clin Invest, 77(3):1014-1019.
8.Gray AJ, Reeves JT, Harrison NK, Winlove P, Laurent GJ (1990). Growth factors for human fibroblasts in the solute remaining after clot formation. J Cell Sci., 96: 271-274.
Nonsubstrate interaction of thrombin with fibrinogen promotes sequential cleavage of fibrinopeptides A and B (FPA and FPB, respectively) from the latter, resulting in its conversion into fibrin1.
Related peptides
The three forms of FPA (AP, A, AY) and two forms of FPB (B, des Arg B) have be identified and quantified in biological samples. Amino acid substitutions in these forms are associated with a number of congenital fibrinogen abnormalities2.
Discovery
In 1951, Lorand et al., reported cleavage of fibrinopeptides from fibrinogen during fibrin clot formation3.
Structural Characteristics
Fibrinogen is cleaved by thrombin at Arg16-Gly17 of the Aa chain and at Arg14-Gly15 of them Bß chain, releasing fibrinopeptides A and B, respectively, and exposing new amino terminal ends of the a and ß - chains, and these are involved in polymerization. FPB cleavage and exposure of the p 15-42 region of the fibrin molecule by thrombin is necessary to stimulate spreading of adherent endothelial cells4. The amino acid sequences of human FPA and FPB are reported to be:H - Ala - Asp - Ser - Gly - Glu - Gly - Asp - Phe - Leu - Ala - Glu - Gly - Gly - Gly - Val - Arg – OH, and Pyr - Gly - Val - Asn - Asp - Asn - Glu - Glu - Gly - Phe - Phe - Ser - Ala - Arg - OH, respectively.
Mode of Action
To convert soluble fibrinogen to insoluble fibrin, thrombin cleaves fibrinopeptide A (FpA, A 1-16) to expose the "A" polymerization site. This "A" site noncovalently interacts with the "a" polymerization site in the C domain of another fibrinogen molecule. This A: a interaction results in the spontaneous formation of half-staggered, double-stranded protofibrils. As these protofibrils grow in length, thrombin cleaves FPB (FpB, B 1-14), which exposes the "B" site and dissociates the C domains from the central E nodule. The release of FpB results in an enhanced rate of lateral aggregation of protofibrils to form thick fibers. Lateral aggregation is supported by multiple interactions, including: a specific, noncovalent interaction between the "B" site and the "b" polymerization site in the C domain of another molecule, intermolecular interactions between C domains of different fibrin molecules, and interactions between 2 C domains of different protofibrils, specifically residues 330 to 375. The end result of thrombin-catalyzed polymerization is the formation of a complex branching network of insoluble fibers5.
Functions
Thrombin cleavage of fibrinogen into FPA and FPB is essential for fibrin clot formation. FPA and FPB, cleavage products of the Aa and Bß chains, respectively, have both been reported to cause vasoconstriction6, and FPB is a chemoattractant for neutrophils and fibroblasts at certain concentrations7. Potentiation of fibroblast proliferation by FPA and FPB has also been suggested7, and both peptides have been found to possess mitogenic activity8.
References
1.Pechik I, Yakovlev S, Mosesson MW, Gilliland GL, Medved L (2006). Structural Basis for Sequential Cleavage of Fibrinopeptides upon Fibrin Assembly. Biochemistry, 45(11): 3588–3597.
2.Southan C, Thompson E, Lane DA (1987). Direct analysis of plasma fibrinogen-derived fibrinopeptides by high-performance liquid chromatography: investigation of nine congenital fibrinogen abnormalities. Br journal of Haematology, 65(4):469-473.
3.Lorand L (1951). 'Fibrino-Peptide'; New Aspects of the Fibrinogen–Fibrin Transformation. Nature, 167(4259):992-993.
4.Sporn LA, Bunce LA, Francis CW (1995). Cell proliferation on fibrin: modulation by fibrinopeptide cleavage. Blood, 86(5):1802-1810.
5.Moen JL, Gorkun OV, Weisel JW, Lord ST(2003). Recombinant BßArg14His fibrinogen implies participation of N-terminus of Bßchain in desA fibrin polymerization. Blood, 102(7): 2466-2471.
6.Bayley T, Clements JA, Osbahr AJ (1967). Pulmonary and circulatory effects of fibrinopeptides. Circ Res., 21 (4):469-485.
7.Senior RM, Skogen WF, Griffin GL, Wilner GD(1986). Effects of fibrinogen derivatives upon the inflammatory response. Studies with human fibrinopeptide B. J Clin Invest, 77(3):1014-1019.
8.Gray AJ, Reeves JT, Harrison NK, Winlove P, Laurent GJ (1990). Growth factors for human fibroblasts in the solute remaining after clot formation. J Cell Sci., 96: 271-274.
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