Fetuin B alleviates testosterone propionate-induced oxidative stress and mitochondrial dysfunction in KGN cells by upregulating the TGFR2/SMAD3 pathway

AbstractBackground Polycystic ovary syndrome (PCOS) is one of the most common reproduction and endocrine disorders. Patients with abnormal follicle growth develop ovulation disorders and amenorrhea, and eventually infertility. The role of Fetuin-B (FETUB), one of the differentially expressed proteins (DEPs) in follicular fluid (FF) of PCOS patients, in pathogenesis of PCOS was not clearly clarified. Methods In this study, we performed iTRAQ-based quantitative proteomic analysis on FF collected from non-PCOS healthy controls and PCOS patients to identify DEPs. In addition, KGN cells treated with testosterone propionate (TP) were used as a model of hyperandrogenism in vitro to investigate the regulatory effects of the selected DEP, FETUB, on cellular processes in KGN cells and its molecular mechanism by detecting steroid hormone secretion, measuring indicators of oxidative stress (OS), mitochondria functions and apoptosis and characterizing the FETUB-altered downstream signaling. Results We found that supplementation with recombinant FETUB could significantly restore the total antioxidant capacity and activity of antioxidant enzymes, which were reduced by treatment with TP. Additionally, FETUB restored the secretory and mitochondrial functions in TP-impaired KGN cells and reduced their apoptosis. Furthermore, our study revealed that FETUB could bind with transforming growth factor beta receptor 2 (TGFR2) on the cell membrane of KGN cells and promote phosphorylation of SMAD3, which had a therapeutic effect against tissue injury and inflammation. And the protective effect of FETUB on TP-treated KGN cells was inhibited by pre-treatment with SB431542 and SIS3, selective inhibitors of TGFR2 and SMAD3, respectively. Conclusions These results indicate that FETUB may protect TP-treated KGN by alleviating OS and mitochondrial dysfunction via the TGFR2-mediated SMAD pathway. Data are available via ProteomeXchange with identifier PXD036531