title: Peptidomic analysis of the neurolysin-knockout mouse brain.
abstract: A large number of intracellular peptides are constantly produced following protein degradation by the proteasome. A few of these peptides function in cell signaling and regulate protein-protein interactions. Neurolysin (Nln) is a structurally defined and biochemically well-characterized endooligopeptidase, and its subcellular distribution and biological activity in the vertebrate brain have been previously investigated. However, the contribution of Nln to peptide metabolism in vivo is poorly understood. In this study, we used quantitative mass spectrometry to investigate the brain peptidome of Nln-knockout mice. An additional in vitro digestion assay with recombinant Nln was also performed to confirm the identification of the substrates and/or products of Nln. Altogether, the data presented suggest that Nln is a key enzyme in the in vivo degradation of only a few peptides derived from proenkephalin, such as Met-enkephalin and octapeptide. Nln was found to have only a minor contribution to the intracellular peptide metabolism in the entire mouse brain. However, further studies appear necessary to investigate the contribution of Nln to the peptide metabolism in specific areas of the murine brain.
  
  
  CONCLUSIONS
  Neurolysin was first identified in the synaptic membranes of the rat brain in the middle 80's by Frederic Checler and colleagues. Neurolysin was well characterized biochemically, and its brain distribution has been confirmed by immunohistochemical methods. The neurolysin contribution to the central and peripheral neurotensin-mediated functions in vivo has been delineated through inhibitor-based pharmacological approaches, but its genuine contribution to the physiological inactivation of neuropeptides remains to be firmly established. As a result, the main significance of this work is the first characterization of the brain peptidome of the neurolysin-knockout mouse. This article is part of a Special Issue entitled: Proteomics, mass spectrometry and peptidomics, Cancun 2013. Guest Editors: César López-Camarillo, Victoria Pando-Robles and Bronwyn Jane Barkla.
authors.affiliation: Department of Pharmacology, Support Center for Research in Proteolysis and Cell Signaling (NAPPS), University of São Paulo, 05508-000 SP, Brazil; Department of Biophysics, Federal University of São Paulo, 04039-032 SP, Brazil.
authors.forename: Leandro M
authors.initials: LM
authors.lastname: Castro
authors.affiliation: Department of Pharmacology, Support Center for Research in Proteolysis and Cell Signaling (NAPPS), University of São Paulo, 05508-000 SP, Brazil.
authors.forename: Diogo M L P
authors.initials: DM
authors.lastname: Cavalcanti
authors.affiliation: Department of Pharmacology, Support Center for Research in Proteolysis and Cell Signaling (NAPPS), University of São Paulo, 05508-000 SP, Brazil.
authors.forename: Christiane B
authors.initials: CB
authors.lastname: Araujo
authors.affiliation: Butantan Institute, LETA-CETICS, 05503-900 São Paulo, SP, Brazil.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Rioli
authors.affiliation: Department of Biophysics, Federal University of São Paulo, 04039-032 SP, Brazil.
authors.forename: Marcelo Y
authors.initials: MY
authors.lastname: Icimoto
authors.affiliation: Chemistry Institute, Campinas State University, 13083-970 Campinas, SP, Brazil.
authors.forename: Fábio C
authors.initials: FC
authors.lastname: Gozzo
authors.affiliation: Department of Biophysics, Federal University of São Paulo, 04039-032 SP, Brazil.
authors.forename: Maria
authors.initials: M
authors.lastname: Juliano
authors.affiliation: Department of Biophysics, Federal University of São Paulo, 04039-032 SP, Brazil.
authors.forename: Luiz
authors.initials: L
authors.lastname: Juliano
authors.affiliation: Department of Biophysics, Federal University of São Paulo, 04039-032 SP, Brazil.
authors.forename: Vitor
authors.initials: V
authors.lastname: Oliveira
authors.affiliation: Department of Pharmacology, Support Center for Research in Proteolysis and Cell Signaling (NAPPS), University of São Paulo, 05508-000 SP, Brazil. Electronic address: emersferro@gmail.com.
authors.forename: Emer S
authors.initials: ES
authors.lastname: Ferro
mesh_terms: D000483:Alleles; D000818:Animals; D001921:Brain / Q000378:metabolism*; D010450:Endopeptidases / Q000737:chemistry; D004745:Enkephalins / Q000737:chemistry; D005838:Genotype; D006454:Hemoglobins / Q000737:chemistry; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009479:Neuropeptides / Q000737:chemistry; D009496:Neurotensin / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry; D010447:Peptide Hydrolases / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011498:Protein Precursors / Q000737:chemistry; D040901:Proteomics; D011994:Recombinant Proteins / Q000737:chemistry; D053719:Tandem Mass Spectrometry
chemical_list: D004745:Enkephalins; D006454:Hemoglobins; D009479:Neuropeptides; D010446:Peptide Fragments; D010455:Peptides; D011498:Protein Precursors; D011994:Recombinant Proteins; C473218:hemopressin; C029992:proenkephalin; D009496:Neurotensin; D010450:Endopeptidases; D010447:Peptide Hydrolases; C028759:oligopeptidase; D008666:Metalloendopeptidases; C022510:thimet oligopeptidase; C062316:neurolysin
keywords: Endopeptidase; Hemopressin; Intracellular peptides; Neurolysin; Oligopeptidase; Peptide metabolism