MicroRNA-1285 Regulates 17β-Estradiol-Inhibited Immature Boar Sertoli Cell Proliferation via Adenosine Monophosphate-Activated Protein Kinase Activation

This study investigated the capacity of 10 mu M 17 beta-estradiol to inhibit immature boar Sertoli cell (SC) proliferation and the involvement of microRNA (miR)-1285 in this process. SC viability and cell cycle progression were investigated using a cell counting kit-8 and flow cytometry, respectively. Expression of AMP-activated protein kinase (AMPK), S phase kinase-associated protein 2 (Skp2), and miR-1285 was analyzed by real-time RT-PCR and Western blotting. 17 beta-Estradiol (10 mu M) reduced SC viability and miR-1285 expression and promoted AMPK phosphorylation. A double-stranded synthetic miR-1285 mimic promoted SC viability, increased levels of ATP, and phosphorylated mammalian target of rapamycin (mTOR) and Skp2 mRNA and protein, whereas p53 and p27 expression decreased, and 17 beta-estradiol-mediated effects on SCs were significantly attenuated. A single-stranded synthetic miR-1285 inhibitor produced the opposite effects on these measures. Activation of AMPK inhibited SC viability, reduced levels of ATP, phosphorylated mTOR and Skp2 mRNA and protein, and increased p53 and p27 expression. An AMPK inhibitor (compound C) attenuated the effects of 17 beta-estradiol on SCs. This indicated that 17 beta-estradiol (10 mu M) reduced SC proliferation by inhibiting miR-1285 and thus activating AMPK. Phosphorylated AMPK is involved in the regulation of 17 beta-estradiol-mediated inhibition of SC viability through increasing p53 and p27 expression and inhibiting mTOR and Skp2 expression. Our findings also implicated Skp2 as the downstream integration point of p53 and mTOR. These findings indicated that miR-1285 may represent a target for the manipulation of boar sperm production.