MicroRNA-27a-3p targeting Vangl1 and Vangl2 inhibits cell proliferation in mouse granulosa cells

Background: Mammalian folliculogenesis is the complex process through which primordial follicles develop into preovulatory follicles. The chief function of ovarian follicle granulosa cells is to play a vital role in the growth, development and atresia of ovarian follicles via gap junctions. Increasing evidence suggests that microRNAs (miRNAs) are essential regulators of granulosa cell apoptosis or proliferation.Methods: The expression level of miR-27a-3p, myogenic differentiation (MyoD), Vangl1 and Vangl2 was inves-tigated by Real-time quantitative PCR (RT-qPCR) and Western blot. Luciferase reporter assay, bioinformatics analysis and ChIP-PCR was used to detect the binding sites between miR-27a-3p, transcription factor and target genes. KEGG pathway analyses were performed to reveal the predicted targets of miR-27a-3p. Ethynyl deoxy-uridine (EdU) proliferation assay was used to measure cell proliferation.Results: To explore the underlying mechanisms of the miR-27a-3p function in the development of mouse gran-ulosa cells (mGCs), we screened for the target genes of miR-27a-3p, confirmed its interaction with Vangl1 and Vangl2 and elucidated their roles in mGCs. MiR-27a-3p inhibited the proliferation of mGCs, whereas target genes Vangl1 and Vangl2 had the opposite effect. In addition, the transcription factor MYOD bound to and activated the promoter of miR-27a-3p. MiR-27a-3p suppressed Vangl1 and Vangl2 expression by targeting their 3 '-untranslated region (3 '-UTR). Furthermore, Vangl1 and Vangl2 suppressed the Wnt pathway by reducing the expression of beta-catenin and B-cell lymphoma/leukemia-2 (Bcl-2).Conclusion: These findings indicate a pro-survival mechanism of the MyoD/miR-27a-3p/Vangl1/Vangl2 axis for granulosa cell proliferation and suggest a novel target for the improvement of female fertility.