FTO-mediated m6A demethylation of BECN1 mRNA promotes hepatic steatosis by impairing autophagy.

N6-methyladenosine (m6A) modification plays a critical role in lipid metabolism, yet the mechanism by which the m6A demethylase Fat mass and obesity-associated protein (FTO) regulates hepatic steatosis and autophagy remains unclear. This study aimed to investigate whether FTO modulates lipid metabolism and autophagy through m6A-dependent regulation of Beclin-1 (BECN1). In vitro, HepG2 cells were treated with free fatty acids (FFA) to establish a lipid overload model. Lipid levels were measured enzymatically; autophagy markers were assessed by Western blot; m6A modification was evaluated via dot blot, MeRIP, and RIP assays; and RNA stability was determined using actinomycin D. In vivo, high-fat diet (HFD)-fed mice were established. Liver histology and lipid profiles were analyzed. FFA treatment reduced global m6A levels and upregulated FTO expression. FTO knockdown attenuated lipid accumulation, improved dyslipidemia, and restored autophagy in HepG2 cells. Mechanistically, FTO directly bound to BECN1 mRNA and demethylated it at the adenine-567 site, thereby inhibiting its stability and expression. Rescue experiments confirmed that BECN1 knockdown reversed the beneficial effects of FTO silencing on lipid metabolism and autophagy. In HFD-fed mice, hepatic FTO knockdown ameliorated steatosis and improved serum and hepatic lipid levels. In conclusion, FTO deficiency enhances BECN1 m6A methylation and mRNA stability, promoting autophagy and ameliorating lipid accumulation. These findings identify FTO as a potential therapeutic target for treating hyperlipidemia and related metabolic disorders.