NSUN7-mediated m5C methylation of NLRP3 promotes pyroptosis in ovarian granulosa cells in polycystic ovary syndrome

Pyroptosis is a pathogenenic mechanism of polycystic ovary syndrome (PCOS). N5-methylcytosine (m5C) methylation is a RNA modification that affects the progression of diseases. However, its role in PCOS remains not understood. This study aimed to investigate the role of NSUN7 in PCOS, particularly its impact on pyroptosis. KGN cells were treated with LPS to establish a cell model, and pyroptosis was evaluated using enzyme-linked immunosorbent assay, flow cytometry, and western blotting. The effect of NSUN7 on the m5C modification of NLRP3 was assessed using methylated RNA immunoprecipitation, dual-luciferase reporter assay, and actinomycin D treatment experiment. A PCOS rat model was generated, hormones were detected using ELISA, and pyroptosis was evaluated in the ovaries and primary granulosa cells. The results showed that NSUN7 expression was reduced in patients with PCOS and LPS-treated KGN cells. Silencing of NSUN7 inhibited LPS-induced cell pyroptosis. Moreover, NSUN7 knockdown inhibited m5C methylation of NLRP3 and reduced NLRP3 mRNA stability. Overexpression of NLRP3 reversed the pyroptosis inhibition induced by NSUN7 knockdown. Furthermore, interfering with NSUN7 alleviated hormone abnormalities and suppressed granulosa cell pyroptosis in PCOS rats. In conclusion, silencing of NSUN7 attenuates PCOS progression by inhibiting pyroptosis of granulosa cells by suppressing m5C methylation of NLRP3.