Abstract

Background Circular RNAs (circRNAs) are implicated in polycystic ovary syndrome (PCOS), yet their roles in granulosa cell dysfunction remain unclear. This study explores the mechanistic role of circ_0075691 in PCOS-associated metabolic dysregulation. Methods The circular structure of circ_0075691 was confirmed through gel electrophoresis and RNase R resistance assays. Its expression levels and subcellular localization were assessed using RT-PCR and fluorescence in situ hybridization (FISH). Subsequent to the overexpression of circ_0075691, the cell function assays were conducted, including CCK-8, colony formation, flow cytometry, and analyses of oxidative stress and lipid metabolism-related indicators. Bioinformatics analyses were employed to predict RNA-binding proteins (RBPs) that potentially interact with circ_0075691, and these interactions were validated using RNA immunoprecipitation (RIP) and RNA pulldown assays. Results Circ_0075691 was verified to possess a circular structure and was predominantly localized in the nucleus. Its expression was significantly elevated in both follicular fluid (FF) and granulosa cells from PCOS patients compared to normal controls. In vitro experiments demonstrated that overexpression of circ_0075691 led to reduced cell viability and proliferation, decreased oxygen consumption rate (OCR), and increased apoptosis, oxidative stress, and lipid accumulation. Mechanistically, circ_0075691 was found to interact with and stabilize the EIF4A3 protein, thereby enhancing the stability of PTGS2 mRNA. Silencing PTGS2 mitigated the metabolic and apoptotic abnormalities induced by circ_0075691. Conclusion This study revealed that circ_0075691 played a crucial role in PCOS-related granulosa cell functions and lipid metabolism. The circ_0075691/EIF4A3/PTGS2 axis provided new insights into the molecular mechanism of PCOS and potential therapeutic targets.