Circular RNAs are involved in the pathogenesis of various diseases, although its expression pattern and role in polycystic ovary syndrome (PCOS), characterised by hyperandrogenism, are not very clear. This article assessed the circRNAs expression profile in the ovaries of PCOS mice by circRNAs high-throughput sequencing and explored the role of circEpha5 in hyperandrogenism. The results showed that the overexpression of circEpha5 in mouse preantral follicles could increase the expression of Cyp17a1, an androgen synthesis-related gene, which resulted in a higher serum level of testosterone. Dual-luciferase reporter gene studies identified miR-758-5p as a direct target of circEpha5. Consequently, miR-758-5p expression was downregulated upon circEpha5 overexpression. Ectopically expressed miR-758-5p reversed the stimulation effects of circEpha5 on steroidogenesis-related gene expression and testosterone release. Therefore, circEpha5 could sponge miR-758-5p to regulate the expression of Cyp17a1, thereby promoting the synthesis and secretion of androgen in the preantral follicles. This work is contributed to the understanding of the pathogenesis of hyperandrogenemia and lays the foundation for the development of therapeutic targets of PCOS hyperandrogenism.
Keywords: Cyp17a1; PCOS; circEpha5; hyperandrogenism; miR-758-5p.
IMPACT STATEMENTWhat is already known on this subject? PCOS is a complex endocrine and metabolic disorders with hyperandrogenism as the main clinical manifestation. There are a variety of abnormal expression circRNAs in PCOS, however, the relationship between circEpha5 and hyperandrogenism has yet to be fully elucidated.What do the results of this study add? We first found that expression levels of serum circEpha5 were significantly higher in PCOS than in a normal group. Using mouse preantral follicle culture model and the letrozole-induced PCOS mouse model, the mechanism of CircEpha5 regulating androgen secretion was studied.What the implications are of these findings for clinical practice and/or further research? It was revealed that CircEpha5 can absorb miR-758-5p in the sponge to regulate the expression of Cyp17a1, thereby promoting the synthesis and secretion of androgen in preantral follicles, which may become a key target for the screening and treatment of PCOS hyperandrogenism.