FTO mediates m6A demethylation of HNF1A and drives hepatic steatosis in metabolic dysfunction-associated steatotic liver disease.

Abstract

OBJECTIVE: Despite advances in understanding metabolic dysfunction-associated steatotic liver disease (MASLD) pathogenesis, effective therapeutic targets remain limited. This study aimed to identify novel regulatory mechanisms by investigating the role of the RNA demethylase FTO in hepatic lipid metabolism. METHODS: MASLD models were established using high-fat diet-fed mice. The expression of m6A modifying enzymes in liver tissue and the overall m6A levels were measured. Lipid deposition was assessed by Oil Red O staining in free fatty acid (FFA)-treated human hepatocytes. The interaction between FTO and HNF1A was explored by co-immunoprecipitation and luciferase reporter assays. Time course experiments evaluated the dynamic changes of m6A and oxidative stress responses. Rescue experiments were performed to verify the functional relationship between FTO and HNF1A. RESULTS: FTO expression was significantly upregulated in the MASLD mouse model, and FTO deficiency significantly increased liver m6A levels. Knockdown of FTO in hepatocytes reduced lipid accumulation and apoptosis. FTO regulates the expression of downstream lipogenic genes via HNF1A, without altering their m6A modification levels. Clinical samples confirmed that FTO was negatively correlated with HNF1A expression. The effects of FTO were significantly reversed by HNF1A knockdown, including lipid droplet generation, cell survival, liver steatosis, and blood metabolic indicators in mice. CONCLUSION: Our findings identify FTO as a key driver of MASLD progression via m6A-dependent regulation of HNF1A, highlighting the FTO-HNF1A axis as a potential therapeutic target.