miR-17-5p affects porcine granulosa cell growth and oestradiol synthesis by targeting E2F1 gene.

Female fertility potential is based on the development and growth of ovarian follicles. Our previous study showed that miR-17-5p was significantly differently expressed in pre-ovulatory ovarian follicles of Large White (LW) and Chinese Taihu (CT) sows. In the present study, we investigated the role of miR-17-5p in ovarian follicle development. We demonstrated that miR-17-5p overexpression significantly decreased the luciferase reporter activity containing the E2F transcription factor 1 (E2F1) 3'untranslated region (3'UTR) and suppressed the E2F1 expression, whereas the miR-17-5p inhibition increased the E2F1 expression in porcine granulosa cells (pGCs). Meanwhile, miR-17-5p overexpression or E2F1 knockdown promoted cell growth, follicular development marker genes (LHR, CYP19A1 and AREG) expression and oestradiol synthesis, and miR-17-5p inhibition suppressed cell growth, follicular development marker genes (LHR, CYP19A1 and AREG) expression and oestradiol synthesis in pGCs. Furthermore, E2F1 knockdown increased CYP19A1 promoter activity. This study suggests that miR-17-5p regulates pGC growth and oestradiol synthesis by targeting E2F1 gene.