Follicular fluid derived exosomal miR-4449 regulates cell proliferation and oxidative stress by targeting KEAP1 in human granulosa cell lines KGN and COV434

Polycystic ovary syndrome (PCOS) is characterized by ovulatory dysfunction, hyperandrogenism, and polycystic ovary morphology, affecting more and more women of reproductive age. Our study aimed to explore the molecular mechanism and effect of exosomal miR-4449 on granulosa cells (GCs). Two immortalized human ovarian granulosa cells (KGN and COV434 cells) were used for in vitro functional studies. Our study found that follicular fluid (FF) derived exosomal miR-4449 was significantly decreased in women with PCOS compared with the control patients. And exosomal miR-4449 could alleviate GCs oxidative stress (OS) and promote GCs proliferation, while the opposite trend was observed after inhibiting the expression of miR-4449. In addition, we demonstrated that Kelch-like ECH-associated protein 1(KEAP1) was a direct target of miR-4449 through dualluciferase reporter assay, and the expression patterns of KEAP1 and miR-4449 in PCOS FF-derived exosomes were exactly opposite. In addition, KEAP1/NRF2 signaling pathway may play an important role in GCs proliferation and OS. Our results demonstrated that the decreased FF-derived exosomal miR-4449 expression in PCOS might aggravate the OS of GCs and inhibit GCs proliferation via KEAP1/NRF2 signaling pathway. Exosomal miR4449 might be a potential biomarker for the diagnosis of PCOS. Our study contributes to a new understanding of the pathogenesis of PCOS.