#43 : Expression of miRNA-21-3p in Polycystic Ovary Syndrome and its Related Functions

Background and Aims: PCOS is an endocrine-related disease related to abnormal folliculogenesis and is a leading cause of infertility worldwide. Inhibition of GCs proliferation and increased GCs apoptosis have been identified as the major factors in aberrant follicle maturation. Recently, the roles of miRNAs were identified in polycystic ovary syndrome (PCOS). For instance, miR-21-3p was identified as an important miRNA regulating autophagy of BGCs. Besides, studies showed that AMSC-EXOs can rescue the polycystic phenotype and metabolic dysfunction in PCOS ovaries by transferring miR-21-5p to the livers of rats with PCOS, finally improve reproduction. However, there is no research clarified the association between miRNA-21-3p and GCs function to date. Method: In the present study, letrozole was used to establish the PCOS rat model. Separate the ovary and then miRNA-21-3p expression will be analyzed by RT-PCR. Primary rat ovarian GCs were isolated and incubated and transfected with mimic or inhibitor of miRNA-21-3p, CCK8 kit was used to detect cell viability, PR-PCR was used to detect cell proliferation and apoptosis related gene expression. Finally, flowcytometry was used to test apoptosis rate of Gcs. Results: The expression of miR-21-3p in the ovaries of PCOS rats was significantly increased compared with that in control rats. Primary rat ovarian GCs were isolated and incubated successfully, and then CCK-8 experiment showed that GCs viability was significantly decreased when miR-21-3p was overexpressed. Additionally, the miR-21-3p mimic significantly decreased the expression of PCNA, Bcl-2, cell cycle-related genes (CDK2, CCNE1) and increased the expression of Bax and caspase3 in primary rat ovarian GCs. By contrast, transfected primary rat ovarian GCs using the miR-21-3p inhibitor significantly upregulated the expression of PCNA, Bcl-2, cell cycle-regulated genes (CDK2, CCNE1) and reduced the expression of Bax and caspase3. Finally, flow cytometry analysis demonstrated that overexpression of miR-21-3p significantly increased the apoptosis rate of GCs. By contrast, the suppression of miR-21-3p resulted in a significant decrease in the apoptosis rate of GCs. Conclusion: In PCOS rat model, miRNA-21-3p was proved significantly increased compared with that in control rats. Which is participant in the development of PCOS by regulating the function of granular cells.