title: Enzyme activity and immunohistochemical localization of dipeptidyl peptidase 8 and 9 in male reproductive tissues.
abstract: The mRNA expression pattern of dipeptidyl peptidase (DPP) 8 and DPP9, two DPP4 homologs, was studied previously and showed a broad tissue distribution. In this study, protein expression and activity of DPP8 and DPP9 were investigated in male reproductive tissues of different mammals. Based on specific DPP activities and inhibition profiles, the proline-selective DPP activity in the bovine and rat testis could predominantly be attributed to DPP8/9 and not to DPP4. This is in contrast to the epididymis, where most of the activity was caused by DPP4. Bovine sperm preparations had very low or undetectable DPP8/9 activity. After characterization of polyclonal antibodies specific for DPP8 or DPP9, we could localize both enzymes in seminiferous tubules of the testis. A specific staining for DPP9 was found associated with spermatozoids embedded in the epithelium, just before their release into the lumen, and in spermatids. DPP8 was localized in spermatozoids in an earlier stage of maturation. These findings help to provide insight into the physiological role of DPP4-like enzymes in the male reproductive system. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
authors.affiliation: Laboratory of Medical Biochemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
authors.forename: Véronique
authors.initials: V
authors.lastname: Dubois
authors.forename: Chris
authors.initials: C
authors.lastname: Van Ginneken
authors.forename: Hilde
authors.initials: H
authors.lastname: De Cock
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Lambeir
authors.forename: Pieter
authors.initials: P
authors.lastname: Van der Veken
authors.forename: Koen
authors.initials: K
authors.lastname: Augustyns
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Simon
authors.initials: S
authors.lastname: Scharpé
authors.forename: Ingrid
authors.initials: I
authors.lastname: De Meester
mesh_terms: D000818:Animals; D002417:Cattle; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D054873:Dipeptidyl-Peptidase IV Inhibitors; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004822:Epididymis / Q000201:enzymology; D005837:Genitalia, Male / Q000201:enzymology*; D015151:Immunoblotting; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology; D007532:Isoleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D009928:Organ Specificity; D010880:Piperidines / Q000494:pharmacology; D011719:Pyrazines / Q000494:pharmacology; D051381:Rats; D000068900:Sitagliptin Phosphate; D013045:Species Specificity; D013094:Spermatozoa / Q000201:enzymology; D013737:Testis / Q000201:enzymology; D014230:Triazoles / Q000494:pharmacology
chemical_list: D054873:Dipeptidyl-Peptidase IV Inhibitors; D007211:Indoles; D010880:Piperidines; D011719:Pyrazines; D014230:Triazoles; C512119:UAMC00039; C524159:UAMC00132; D007532:Isoleucine; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C527707:Dpp8 protein, rat; C527708:Dpp9 protein, rat; D018819:Dipeptidyl Peptidase 4; D000068900:Sitagliptin Phosphate