Thimet oligopeptidase and prolyl endopeptidase of spotted scat Scatophagus argus: characterization, tissue distribution, expression at different ovarian stages and down-regulation by estradiol
Thimet oligopeptidase (Top) is a thiol-sensitive metallopeptidase with increased concentrations in brain and reproductive tissues. Prolyl endopeptidase (Pep) is another endopeptidase with high enzymatic activity in the brain. The two neuropeptidases are involved in the degradation of gonadotropin-releasing hormone. To clarify their roles in reproductive regulation, the spotted scat top (sstop) and pep (sspep) genes were cloned and analyzed. Tissue distribution by RT-PCR showed that sstop and sspep were more highly expressed in reproduction-related tissues than in other tissues. The sstop and sspep mRNA was detected in female hypothalamuses at phase II (oocytes at the perinuclear stage), phase III (oocytes forming the vitelline vesicle) and phase IV (oocytes at lipidic and proteic vitellogenesis stages). Both sstop and sspep were highly expressed in phase III, moderately in phase IV, and the lowest in phase II. The sstop and sspep genes were down-regulated in hypothalamuses after treatment with estradiol both in vitro and in vivo. It is suggested that Sstop and Sspep play significant roles in the regulation of reproduction and these results suggested an ssTop- and ssPep-mediated positive feedback mechanism of ovarian function.
KeywordsScatophagus argus Thimet oligopeptidase Prolyl endopeptidase Hypothalamuses 17β-Estradiol
Spotted scat top
Spotted scat pep
This study was supported by the Natural Science Foundation of Guangdong Province (2016A030313743, 2017A030313101); Marine Fishery Science and Technology Extension Projects of Guangdong (A201608B01, 2017A0012); Introduction of Talent Research Project of Guangdong Ocean University (0712103); The National Natural Science Foundation of China (41706174, 31702326); Zhanjiang Science and Technology Bureau (2016A03017) and the College Students’ Innovation and Entrepreneurship Project (201610566007, CXXL2018132).
Compliance with ethical standards
Human and animal rights
All animal experiments throughout the study were conducted in accordance with the Regulations for the Administration of Affairs Concerning Experimental Animals for the Science and Technology Bureau of China.
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