Enzyme Activity and Immunohistochemical Localization of Dipeptidyl Peptidase 8 and 9 in Male Reproductive Tissues

Abstract

(XC) S U M M A R Y 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. (J Histochem Cytochem 57:531-541, 2009)

Contribution of upregulated dipeptidyl peptidase 9 (DPP9) in promoting tumoregenicity, metastasis and the prediction of poor prognosis in non‐small cell lung cancer (NSCLC)

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Selective Inhibitors of Fibroblast Activation Protein (FAP) with a (4-Quinolinoyl)-glycyl-2-cyanopyrrolidine Scaffold

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Increased sex chromosome expression and epigenetic abnormalities in spermatids from male mice with Y chromosome deletions

“…As the increased transcription of genes in the MSYq deletion mice is thought to lead to a corresponding increase in their encoded proteins, we decided to examine the expression of the EGFP transgene at the protein level. Western blot analysis demonstrated that GFP levels are increased by more than twofold in the 2/3MSYq-testes compared to XY controls using both a whole testis (actin) or spermatid-specific (DPP9) (Dubois et al, 2009) protein as a loading control (Fig. 2A,B and supplementary material Fig.…”