MicroRNA miR-125b can suppress ovarian granulosa cell functions: Interrelationships with FSH

This study aimed to evaluate the involvement of miR-125b and its interrelationship with follicle-stimulating hormone (FSH) in the control of basic ovarian granulosa cell functions. The effect of miR-125b mimics on basic functions of porcine ovarian granulosa cells cultured with and without FSH, and the effect of FSH on the expression of endogenous miR-125b was examined. Expression levels of miR-125b, viability, proliferation (accumulation of PCNA and cyclin B1), apoptosis (accumulation of bax and caspase 3), the accumulation of FSH receptors (FSHR), steroid hormones, insulin-like growth factor I (IGF-I), oxytocin, and prostaglandin E2 release were analysed by reverse transcription-quantitative polymerase chain reaction, Trypan blue exclusion test, quantitative immunocytochemistry, and ELISA. Transfection of cells with miR-125b mimics inhibited cell viability, proliferation, apoptosis, the occurrence of FSHR, progesterone, testosterone, estradiol, and oxytocin release but stimulated prostaglandin E2 output. FSH promoted cell viability, proliferation, steroid hormones, IGF-I, oxytocin, and prostaglandin E2 output and reduced the expression of miR-125b and apoptosis. Furthermore, miR-125b mimics supported the effect of FSH on the release of estradiol, IGF-I, and prostaglandin E2, and inverted FSH influence on cell viability, proliferation, apoptosis, progesterone, and testosterone output. FSH supported both inhibitory and stimulatory action of miR-125b on ovarian cell functions. Present observations indicate that: miR-125b can be involved in the control of basic ovarian functions and that miR-125b and FSH are antagonists in their actions on ovarian cell functions. The ability of FSH to reduce miR-125b expression and the ability of miR-125b mimics to decrease the occurrence of FSHR and to modify FSH effects indicate the existence of the self-inhibiting FSH-miR-125b axis and that miR-125b can mediate the actions of FSH on ovarian cells.