title: Neuropeptide Y (NPY) cleaving enzymes: structural and functional homologues of dipeptidyl peptidase 4.
abstract: N-terminal truncation of NPY has important physiological consequences, because the truncated peptides lose their capability to activate the Y1-receptor. The sources of N-terminally truncated NPY and related peptides are unknown and several proline specific peptidases may be involved. First, we therefore provide an overview on the peptidases, belonging to structural and functional homologues of dipeptidyl peptidase 4 (DP4) as well as aminopeptidase P (APP) and thus, represent potential candidates of NPY cleavage in vivo. Second, applying selective inhibitors against DP4, DP8/9 and DP2, respectively, the enzymatic distribution was analyzed in brain extracts from wild type and DP4 deficient F344 rat substrains and human plasma samples in activity studies as well as by matrix assisted laser desorption/ionisation-time of flight (MALDI-TOF)-mass spectrometry. Third, co-transfection of Cos-1 cells with Dpp4 and Npy followed by confocal lasermicroscopy illustrated that hNPY-dsRed1-N1 was transported in large dense core vesicles towards the membrane while rDP4-GFP-C1 was transported primarily in different vesicles thereby providing no clear evidence for co-localization of NPY and DP4. Nevertheless, the review and experimental results of activity and mass spectrometry studies support the notion that at least five peptidases (DP4, DP8, DP9, XPNPEP1, XPNPEP2) are potentially involved in NPY cleavage while the serine protease DP4 (CD26) could be the principal peptidase involved in the N-terminal truncation of NPY. However, DP8 and DP9 are also capable of cleaving NPY, whereas no cleavage could be demonstrated for DP2.
authors.affiliation: Department of Functional and Applied Anatomy, Hannover Medical School, OE 4120, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Frerker
authors.forename: Leona
authors.initials: L
authors.lastname: Wagner
authors.forename: Raik
authors.initials: R
authors.lastname: Wolf
authors.forename: Ulrich
authors.initials: U
authors.lastname: Heiser
authors.forename: Torsten
authors.initials: T
authors.lastname: Hoffmann
authors.forename: Jens-Ulrich
authors.initials: JU
authors.lastname: Rahfeld
authors.forename: Jutta
authors.initials: J
authors.lastname: Schade
authors.forename: Tim
authors.initials: T
authors.lastname: Karl
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Naim
authors.forename: Marwan
authors.initials: M
authors.lastname: Alfalah
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Demuth
authors.forename: Stephan
authors.initials: S
authors.lastname: von Hörsten
mesh_terms: D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D017931:DNA Primers; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D006868:Hydrolysis; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009478:Neuropeptide Y / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D017931:DNA Primers; D009478:Neuropeptide Y; D018819:Dipeptidyl Peptidase 4