Skip to main content
PMC home page
The AAPS Journal logoLink to The AAPS Journal
. 2005 Oct 5;7(2):E449–E455. doi: 10.1208/aapsj070244

Neuropeptide-processing enzymes: Applications for drug discovery

Lloyd D Fricker 1,✉
PMCID: PMC2750981  PMID: 16353923

Abstract

Neuropeptides serve many important roles in communication between cells and are an attractive target for drug discovery. Neuropeptides are produced from precursor proteins by selective cleavages at specific sites, and are then broken down by further cleavages. In general, the biosynthetic cleavages occur within the cell and the degradative cleavages occur postsecretion, although there are exceptions where intracellular processing leads to inactivation, or extracellular processing leads to activation of a particular neuropeptide. A relatively small number of peptidases are responsible for processing the majority of neuropeptides, both inside and outside of the cell. Thus, inhibition of any one enzyme will lead to a broad effect on several different neuropeptides and this makes it unlikely that such inhibitors would be useful therapeutics. However, studies with mutant animals that lack functional peptide-processing enzymes have facilitated the discovery of novel neuropeptides, many of which may be appropriate targets for therapeutics.

Keywords: carboxypeptidase, peptidomics, prohormone convertase, peptide biosynthesis

Full Text

The Full Text of this article is available as a PDF (180.5 KB).

References

  • 1.Clynen E, Loof A, Schoofs L. The use of peptidomics in endocrine research. Gen Comp Endocrinol. 2003;132:1–9. doi: 10.1016/S0016-6480(03)00158-8. [DOI] [PubMed] [Google Scholar]
  • 2.Strand FL. Neuropeptides: general characteristics and neuropharmaceutical potential in treating CNS disorders. Prog Drug Res. 2003;61:1–37. doi: 10.1007/978-3-0348-8049-7_1. [DOI] [PubMed] [Google Scholar]
  • 3.Tanaka H, Yoshida T, Miyamoto N, et al. Characterization of a family of endogenous neuropeptide ligands for the G protein-coupled receptors GPR7 and GPR8. Proc Natl Acad Sci USA. 2003;100:6251–6256. doi: 10.1073/pnas.0837789100. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Docherty K, Steiner DF. Post-translational proteolysis in polypeptide hormone biosynthesis. Annu Rev Physiol. 1982;44:625–638. doi: 10.1146/annurev.ph.44.030182.003205. [DOI] [PubMed] [Google Scholar]
  • 5.Lindberg I, Hutton JC. Peptide processing proteinases with selectivity for paired basic residues. In: Fricker LD, editor. Peptide Biosynthesis and Processing. Boca Raton, FL: CRC Press; 1991. pp. 141–174. [Google Scholar]
  • 6.Devi L. Peptide processing at monobasic sites. In: Fricker LD, editor. Peptide Biosynthesis and Processing. Boca Raton, FL: CRC Press; 1991. pp. 175–198. [Google Scholar]
  • 7.Zhou A, Webb G, Zhu X, Steiner DF. Proteolytic processing in the secretory pathway. J Biol Chem. 1999;274:20745–20748. doi: 10.1074/jbc.274.30.20745. [DOI] [PubMed] [Google Scholar]
  • 8.Seidah NG, Prat A. Precursor convertases in the secretory pathway, cytosol and extracellular milieu. Essays Biochem. 2002;38:79–94. doi: 10.1042/bse0380079. [DOI] [PubMed] [Google Scholar]
  • 9.Che F-Y, Yan L, Li H, Mzhavia N, Devi L, Fricker LD. Identification of peptides from brain and pituitary ofCpefat/Cpefat mice. Proc Natl Acad Sci USA. 2001;98:9971–9976. doi: 10.1073/pnas.161542198. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 10.Sigafoos J, Chestnut WG, Merrill BM, Taylor LCE, Diliberto EJ, Viveros OH. Novel peptides from adrenomedullary chromaffin vesicles. J Anat. 1993;183:253–264. [PMC free article] [PubMed] [Google Scholar]
  • 11.Vilim FS, Aarnisalo AA, Nieminen M, et al. Gene for pain modulatory neuropeptide NPFF: induction in spinal cord by noxious stimuli. Mol Pharmacol. 1999;55:804–811. [PubMed] [Google Scholar]
  • 12.Che F-Y, Fricker LD. Quantitation of neuropeptides inCpefat/Cpefat mice using differential isotopic tags and mass spectrometry. Anal Chem. 2002;74:3190–3198. doi: 10.1021/ac015681a. [DOI] [PubMed] [Google Scholar]
  • 13.Che F-Y, Fricker LD. Quantitative peptidomics of mouse pituitary: comparison of different stable isotopic tags. J Mass Spectrom. 2005;40:238–249. doi: 10.1002/jms.743. [DOI] [PubMed] [Google Scholar]
  • 14.Che F-Y, Biswas R, Fricker LD. Relative quantitation of peptides in wild type andCpefat/fat mouse pituitary using stable isotopic tags and mass spectrometry. J Mass Spectrom. 2005;40:227–237. doi: 10.1002/jms.742. [DOI] [PubMed] [Google Scholar]
  • 15.Pan H, Nanno D, Che FY, et al. Neuropeptide processing profile in mice lacking prohormone Convertase-1. Biochemistry. 2005;44:4939–4948. doi: 10.1021/bi047852m. [DOI] [PubMed] [Google Scholar]
  • 16.Che FY, Yuan Q, Kalinina E, Fricker LD. Peptidomics of Cpefat/fat mouse hypothalamus: effect of food deprivation and exercise on peptide levels. J Biol Chem. 2005;280:4451–4461. doi: 10.1074/jbc.M411178200. [DOI] [PubMed] [Google Scholar]
  • 17.Smeekens SP, Steiner DF. Identification of a human insulinoma cDNA encoding a novel mammalian protein structurally related to the yeast dibasic processing protease Kex2. J Biol Chem. 1990;265:2997–3000. [PubMed] [Google Scholar]
  • 18.Seidah NG, Marcinkiewicz M, Benjannet S, et al. Cloning and primary sequence of a mouse candidate prohormone convertase PC1 homologous to PC2, furin, and Kex2: distinct chromosomal localization and messenger RNA distribution in brain and pituitary compared to PC2. Mol Endocrinol. 1991;5:111–122. doi: 10.1210/mend-5-1-111. [DOI] [PubMed] [Google Scholar]
  • 19.Smeekens SP, Avruch AS, LaMendola J, Cham SJ, Steiner DF. Identification of a cDNA encoding a second putative prohormone convertase related to PC2 in AtT-20 cells and islets of Langerhans. Proc Natl Acad Sci USA. 1991;88:340–344. doi: 10.1073/pnas.88.2.340. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20.Schafer MKH, Day R, Cullinan WE, Chretien M, Seidah NG, Watson SJ. Gene expression of prohormone and proprotein convertases in the rat CNS: a comparative in situ hybridization analysis. J Neurosci. 1993;13:1258–1279. doi: 10.1523/JNEUROSCI.13-03-01258.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Braks JAM, Martens GJM. 7B2 is a neuroendocrine chaperone that transiently interacts with prohormone convertase PC2 in the secretory pathway. Cell. 1994;78:263–273. doi: 10.1016/0092-8674(94)90296-8. [DOI] [PubMed] [Google Scholar]
  • 22.Fricker LD, McKinzie AA, Sun J, et al. Identification and characterization of proSAAS, a granin-like neuroendocrine peptide precursor that inhibits prohormone processing. J Neurosci. 2000;20:639–648. doi: 10.1523/JNEUROSCI.20-02-00639.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Zhu X, Rouille Y, Lamango NS, Steiner DF, Lindberg I. Internal cleavage of the inhibitory 7B2 CT peptide by PC2: a potential mechanism for its inactivation. Proc Natl Acad Sci USA. 1996;93:4919–4924. doi: 10.1073/pnas.93.10.4919. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 24.Cameron A, Fortenberry Y, Lindberg I. The SAAS granin exhibits structural and functional homology to 7B2 and contains a highly potent hexapeptide inhibitor of PC1. FEBS Lett. 2000;473:135–138. doi: 10.1016/S0014-5793(00)01511-8. [DOI] [PubMed] [Google Scholar]
  • 25.Furuta M, Yano H, Zhou A, et al. Defective prohormone processing and altered pancreatic islet morphology in mice lacking active SPC2. Proc Natl Acad Sci USA. 1997;94:6646–6651. doi: 10.1073/pnas.94.13.6646. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Furuta M, Zhou A, Webb G, et al. Severe defect in proglucag on processing in islet A-cells of prohormone convertase 2 null mice. J Biol Chem. 2001;276:27197–27202. doi: 10.1074/jbc.M103362200. [DOI] [PubMed] [Google Scholar]
  • 27.Zhu X, Orci L, Carroll R, Norrbom C, Ravazzola M, Steiner DF. Severe block in processing of proinsulin to insulin accompanied by elevation of des-64,65 proinsulin internediates in islets of mice lacking prohormone convertase 1/3. Proc Natl Acad Sci USA. 2002;99:10299–10304. doi: 10.1073/pnas.162352799. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 28.Zhou A, Bloomquist BT, Mains RE. The prohormone convertases PC1 and PC2 mediate distinct endoproteolytic cleavages in a strict temporal order during proopiomelanocortin biosynthetic processing. J Biol Chem. 1993;268:1763–1769. [PubMed] [Google Scholar]
  • 29.Breslin MB, Lindberg I, Benjannet S, Mathis JP, Lazure C, Seidah NG. Differential processing of proenkephalin by prohormone convertases 1(3) and 2 and furin. J Biol Chem. 1993;268:27084–27093. [PubMed] [Google Scholar]
  • 30.Zhou A, Mains RE. Endoproteolytic processing of proopiomelanocortin and prohormone convertases 1 and 2 in neuroendocrine cells overexpressing prohormone convertases 1 or 2. J Biol Chem. 1994;269:17440–17447. [PubMed] [Google Scholar]
  • 31.Fricker LD, Snyder SH. Enkephalin convertase: purification and characterization of a specific enkephalin-synthesizing carboxypeptidase localized to adrenal chromaffin granules. Proc Natl Acad Sci USA. 1982;79:3886–3890. doi: 10.1073/pnas.79.12.3886. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Fricker LD. Carboxypeptidase E. Annu Rev Physiol. 1988;50:309–321. doi: 10.1146/annurev.ph.50.030188.001521. [DOI] [PubMed] [Google Scholar]
  • 33.Aloy P, Companys V, Vendrell J, et al. The crystal structure of the inhibitor-complexed carboxypeptidase D domain II as a basis for the modelling of regulatory carboxypeptidases. J Biol Chem. 2001;276:16177–16184. doi: 10.1074/jbc.M011457200. [DOI] [PubMed] [Google Scholar]
  • 34.Nalamachu SR, Song L, Fricker LD. Regulation of carboxypeptidase E: effect of Ca2+ on enzyme activity and stability. J Biol Chem. 1994;269:11192–11195. [PubMed] [Google Scholar]
  • 35.Fricker LD, Snyder SH. Purification and characterization of enkephalin convertase, an enkephalin-synthesizing carboxypeptidase. J Biol. Chem. 1983;258:10950–10955. [PubMed] [Google Scholar]
  • 36.Smyth DG, Maruthainar K, Darby NJ, Fricker LD. C-terminal processing of neuropeptides: involvement of carboxypeptidase H. J Neurochem. 1989;53:489–493. doi: 10.1111/j.1471-4159.1989.tb07360.x. [DOI] [PubMed] [Google Scholar]
  • 37.Chen H, Jawahar S, Qian Y, et al. A missense polymorphism in the human carboxypeptidase E gene alters its, enzymatic activity: possible implications in type 2 diabetes mellitus. Hum Mutat. 2001;18:120–131. doi: 10.1002/humu.1161. [DOI] [PubMed] [Google Scholar]
  • 38.Naggert JK, Fricker LD, Varlamov O, et al. Hyperproinsulinemia in obesefat/fat mice associated with a point mutation in the carboxypeptidase E gene and reduced carboxypeptidase E activity in the pancreatic islets. Nat Genet. 1995;10:135–142. doi: 10.1038/ng0695-135. [DOI] [PubMed] [Google Scholar]
  • 39.Varlamov O, Leiter EH, Fricker LD. Induced and spontaneous mutations at Ser202 of carboxypeptidase E: effect on enzyme expression, activity, and intracellular routing. J Biol Chem. 1996;271:13981–13986. doi: 10.1074/jbc.271.24.13981. [DOI] [PubMed] [Google Scholar]
  • 40.Fricket LD, Berman YL, Leiter EH, Devi LA. Carboxypeptidase E activity is deficient in mice with the fat mutation: effect on peptide processing. J Biol Chem. 1996;271:30619–30624. doi: 10.1074/jbc.271.48.30619. [DOI] [PubMed] [Google Scholar]
  • 41.Rovere C, Viale A, Nahon J, Kitabgi P. Impaired processing of brain proneurotensin and promelanin-concentrating hormone in obesefat/fat mice. Endocrinology. 1996;137:2954–2958. doi: 10.1210/en.137.7.2954. [DOI] [PubMed] [Google Scholar]
  • 42.Udupi V, Gomez P, Song L, et al. Effect of carboxypeptidase E deficiency on progastrin processing and gastrin mRNA expression in mice with the fat mutation. Endocrinology. 1997;138:1959–1963. doi: 10.1210/en.138.5.1959. [DOI] [PubMed] [Google Scholar]
  • 43.Cain BM, Wang W, Beinfeld MC. Cholecystokinin (CCK) levels are greatly reduced in the brains but not the duodenums ofCpefat/Cpefat mice: a regional difference in the involvement of carboxypeptidase E (Cpe) in pro-CCK processing. Endocrinology. 1997;138:4034–4037. doi: 10.1210/en.138.9.4034. [DOI] [PubMed] [Google Scholar]
  • 44.Song L, Fricker LD. Purification and characterization of carboxypeptidase D, a novel carboxypeptidase E-like enzyme, from bovine pituitary. J Biol Chem. 1995;270:25007–25013. doi: 10.1074/jbc.270.42.25007. [DOI] [PubMed] [Google Scholar]
  • 45.Varlamov O, Fricker LD. Intracellular trafficking of metallocarboxypeptidase D in AtT-20 cells: localization to the trans-Golgi network and recycling from the cell surface. J Cell Sci. 1998;111:877–885. doi: 10.1242/jcs.111.7.877. [DOI] [PubMed] [Google Scholar]
  • 46.Varlamov O, Eng FJ, Novikova EG, Fricker LD. Localization of metallocarboxypeptidase D in AtT-20 cells: potential role in prohormone processing. J Biol Chem. 1999;274:14759–14767. doi: 10.1074/jbc.274.21.14759. [DOI] [PubMed] [Google Scholar]
  • 47.Eipper BA, Milgram SL, Husten EJ, Yun HY, Mains RE. Peptidylglycine alpha-amidating monooxygenase: a multifunctional protein with catalytic, processing, and routing domains. Protein Sci. 1993;2:489–497. doi: 10.1002/pro.5560020401. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 48.Ouafik LH, Stoffers DA, Campbell TA, et al. The multifunctional peptidylglycine alpha-amidating monooxygenase gene: exon/intron organization of catalytic, processing, and routing domains. Mol Endo crinol. 1992;6:1571–1584. doi: 10.1210/me.6.10.1571. [DOI] [PubMed] [Google Scholar]
  • 49.Prigge ST, Mains RE, Eipper BA, Amzel LM. New insights into copper monooxygenase and peptide amidation: structure, mechanism, and function. Cell Mol Life Sci. 2000;57:1236–1259. doi: 10.1007/PL00000763. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 50.Kolhekar AS, Mains RE, Eipper BA. Peptidylglycine alpha-amidating monooxygenase: an ascorbate-requiring enzyme. Meth Enzymol. 1997;279:34–43. doi: 10.1016/s0076-6879(97)79007-4. [DOI] [PubMed] [Google Scholar]
  • 51.Bradbury AF, Smyth DG. Modification of the N-and C-termini of bioactive peptides: amidation and acetylation. In: Fricker LD, editor. Peptide Biosynthesis and Processing. Boca Raton, FL: CRC Press; 1991. pp. 231–250. [Google Scholar]
  • 52.Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402:656–660. doi: 10.1038/45230. [DOI] [PubMed] [Google Scholar]
  • 53.Lee RWH, Huttner WB. Tyrosine O-sulfated proteins of PC1 pheochromocytoma cells and their sulfation by tyrosylprotein sulfotransferase. J Biol Chem. 1983;258:11326–11332. [PubMed] [Google Scholar]
  • 54.Bennett HPJ. Glycosylation, phosphorylation, and sulfation of peptide hormones and their precursors. In: Fricker LD, editor. Peptide Biosynthesis and Processing. Boca Raton, FL: CRC Press; 1991. pp. 111–140. [Google Scholar]
  • 55.Svensson M, Skold K, Svenningsson P, Andren PE. Peptidomicsbased discovery of novel neuropeptides. J Proteome Res. 2003;2:213–219. doi: 10.1021/pr020010u. [DOI] [PubMed] [Google Scholar]
  • 56.Turner AJ. Exploring the structure and function of zinc metallopeptidases: old enzymes and new discoveries. Biochem Soc Trans. 2003;31:723–727. doi: 10.1042/BST0310723. [DOI] [PubMed] [Google Scholar]
  • 57.Albiston AL, Ye S, Chai SY. Membrane bound members of the M1 family: more than aminopeptidases. Protein Pept Lett. 2004;11:491–500. doi: 10.2174/0929866043406643. [DOI] [PubMed] [Google Scholar]
  • 58.Kim SI, Grum-Tokars V, Swanson TA, et al. Novel roles of neuropeptide processing enzymes: EC3.4.24.15 in the neurome. J Neurosci Res. 2003;74:456–467. doi: 10.1002/jnr.10779. [DOI] [PubMed] [Google Scholar]
  • 59.Smith AI, Clarke IJ, Lew RA. Post-secretory processing of peptide signals: a novel mechanism for the regulation of peptide hormone receptors. Biochem Soc Trans. 1997;25:1011–1014. doi: 10.1042/bst0251011. [DOI] [PubMed] [Google Scholar]
  • 60.Goumon Y, Lugardon K, Gadroy P, et al. Processing of proenkephalin-A in bovine chromaffin cells. Identification of natural derived fragments by N-terminal sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Biol Chem. 2000;275:38355–38362. doi: 10.1074/jbc.M007557200. [DOI] [PubMed] [Google Scholar]
  • 61.Wei S, Segura S, Vendrell J, et al. Identification and characterization of three membrers of the human metallocarboxypeptidase gene family. J Biol Chem. 2002;277:14954–14964. doi: 10.1074/jbc.M112254200. [DOI] [PubMed] [Google Scholar]
  • 62.Fontenele-Neto JD, Kalinina E, Feng Y, Fricker LD. Identification and distribution of mouse carboxypeptidase A-6.Brain Res Mol Brain Res. [DOI] [PubMed]
  • 63.Emoto N, Yanagisawa M. Endothelin-converting enzyme-2 is a membrane-bound, phosphoramidon-sensitive metalloprotease with acidic pH optimum. J Biol Chem. 1995;270:15262–15268. doi: 10.1074/jbc.270.25.15262. [DOI] [PubMed] [Google Scholar]
  • 64.Mzhavia N, Pan H, Che F-Y, Fricker LD, Devi LA. Characterization of endothelin-converting enzyme-2. Implication for a role in the nonclassical processing of regulatory peptides. J Biol Chem. 2003;278:14704–14711. doi: 10.1074/jbc.M211242200. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 65.Srinivasan S, Bunch DO, Feng Y, et al. Deficits in reproduction and pro-gonadotropin-releasing hormone processing in male Cpefat mice. Endocrinology. 2004;145:2023–2034. doi: 10.1210/en.2003-1442. [DOI] [PubMed] [Google Scholar]
  • 66.Qian Y, Devi LA, Mzhavia N, Munzer S, Seidah NG, Fricker LD. The C-terminal region of proSAAS is a potent inhibitor of prohormone convertase 1. J Biol Chem. 2000;275:23596–23601. doi: 10.1074/jbc.M001583200. [DOI] [PubMed] [Google Scholar]
  • 67.Wei S, Feng Y, Che F-Y, et al. Obesity and diabetes in transgenic mice expressing proSAAS. J Endocrinol. 2004;180:357–368. doi: 10.1677/joe.0.1800357. [DOI] [PubMed] [Google Scholar]
  • 68.Sakurai T, Amemiya A, Ishii M, et al. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G-protein-coupled receptors that regulate feeding behavior. Cell. 1998;92:573–585. doi: 10.1016/S0092-8674(00)80949-6. [DOI] [PubMed] [Google Scholar]
  • 69.Preti A. Orexins (hypocretins): their role in appetite and arousal. Curr Opin Investig Drugs. 2002;3:1199–1206. [PubMed] [Google Scholar]
  • 70.Rodgers RJ, Ishii Y, Halford JC, Blundell JE. Orexins and appetite regulation. Neuropeptides. 2002;36:303–325. doi: 10.1016/S0143-4179(02)00085-9. [DOI] [PubMed] [Google Scholar]
  • 71.Tao WA, Aebersold R. Advances in quantitative proteomics via stable isotope tagging and mass spectrometry. Curr Opin Biotechnol. 2003;14:110–118. doi: 10.1016/S0958-1669(02)00018-6. [DOI] [PubMed] [Google Scholar]
  • 72.Goshe MB, Smith RD. Stable isotope-coded proteomic mass spectrometry. Curr Opin Biotechnol. 2003;14:101–109. doi: 10.1016/S0958-1669(02)00014-9. [DOI] [PubMed] [Google Scholar]
  • 73.Che F-Y, Eipper BA, Mains RE, Fricker LD. Quantitative peptidomics of pituitary glands from mice deficient in copper transport. Cell Mol Biol. 2003;49:713–722. [PubMed] [Google Scholar]

Articles from The AAPS Journal are provided here courtesy of American Association of Pharmaceutical Scientists

RESOURCES