MC-LR induced overproduction of progesterone via inhibiting miR-3473g: in vitro and in vivo evidence

Health risk of human exposure to microcystin-leucine arginine (MC-LR) has drawn more and more attention in recent years. In the present study, MC-LR inhibited miR-3473g expression of mouse granulosa cells both in vitro and in vivo. By dual-luciferase reporter assay, we confirmed miR-3473g is able to bind the 3'-UTR of StAR protein (StAR) mRNA and suppress StAR expression. Thus, downregulation of miR-3473g after MC-LR exposure led to StAR overexpression. Excessive StAR probably transported much more cholesterol into the inner membrane of the mitochondria and finally resulted in overproduction of progesterone. Our results revealed that MC-LR exposure was associated with premature luteinization of granulosa cells and may adversely affect women's fertility.