MiR-31 targets HSD17B14 and FSHR, and miR-20b targets HSD17B14 to affect apoptosis and steroid hormone metabolism of porcine ovarian granulosa cells

Porcine 17-hydroxysteroid dehydrogenase type 14 (HSD17B14) and FSH reporter (FSHR) genes play important roles in the metabolism of steroid hormones and the apoptosis of ovarian granulosa cells (GCs). Our bioinformatics analyses and the dual luciferase reporter assays indicated that porcine miR-20b and miR-31 target the 3'-UTR region of HSD17B14 gene, and miR-31 also targets the 3'-UTR region of FSHR gene. Overexpression of porcine HSD17B14 gene promoted the conversion from estradiol (E2) to estrone (E1) and increased the apoptosis of porcine GCs. Overexpression of miR-20b down-regulated the mRNA and protein expression level of HSD17B14 gene, decreased the concentration of progesterone (P4) and E1, increased E2, as well as reduced apoptosis of GCs. Moreover, overexpression of miR-31 also down-regulated the protein expression level of HSD17B14 gene, decreased the concentration of P4 and E1, and increased E2. However, miR-31 promoted apoptosis of GCs by targeting to the 3'-UTR of porcine FSHR gene. Taken together, we found that both porcine miR-20b and miR-31 target HSD17B14 gene, but miR-31 also targets FSHR gene to regulate the metabolism of steroid hormones and the apoptosis of porcine ovarian GCs. These findings expand the epigenetic regulatory mechanism of porcine miR-31 and miR-20b in ovarian GCs.