[miR-383 inhibits proliferation of granulosa cells by down-regulation of cell cycle-related proteins in mice].

Objective To investigate the expression of microRNA-383 (miR-383) in viability classification of growing follicles and its biological function on proliferation and cycle of granulosa cells. Methods The expression of miR-383 in ovaries tissues, follicles and granulosa cells extracted from Kunming mice after birth of 12, 21 days, 21 days [after injection of pregnant mare serum gonadotropin (PMSG) for 48 hours] and 21 days [after injection of PMSG for 48 hours and (human chorionic gonadotrophin) hCG for 6 hours] were detected by real-time quantitative PCR. The miR-383 mimics or miR-383 inhibitor were transfected into granulosa cells extracted from Kunming mice after birth of 21 days, respectively as miR-383 mimics group and miR-383 inhibitor group. Meanwhile, we established negative control (NC) group. MTT assay was used to detect the proliferation and flow cytometry was used to detect cell cycle of granulosa cells. And the levels of cyclin D1, cyclin B, CDK1, CDK2, and CDK4 protein were tested by Western blot analysis. Results Compared with small preantral follicles, miR-383 level in big preantral follicles and big antral follicles were both lower, but miR-383 in small antral follicles was higher. Similarly, miR-383 of granulosa cells in big preantral follicles and small antral follicles were lower than that of granulosa cells in small preantral follicles, but up-regulated in granulosa cells of big antral follicles. Compared with granulosa cells in the NC group, the proliferation activity of granulosa cells in miR-383 mimics group was lower, and there was more granulosa cells in G0/G1 phase, less in G2/M phase in miR-383 mimics group, besides cyclin D1, cyclinB, CDK1, CDK2, CDK4 proteins in miR-383 mimics group were all lower. Meanwhile, the proliferation activity of granulosa cells in miR-383 inhibitor group was higher, and there was less granulosa cells in G0/G1 phase, more in G2/M phase in miR-383 inhibitor group, besides cyclinD1, cyclinB, CDK1, CDK2, CDK4 proteins in miR-383 inhibitor group were all higher than those proteins in the NC group. Conclusion miR-383 inhibits the proliferation of granulosa cells by down-regulating of cycle-related proteins and blocking granulosa cells in G0/G1 phase.