Abstract
OBJECTIVE: To investigate the effect of methyltransferase-like 3 (METTL3) inhibitor STM2457 in metabolic dysfunction-associated fatty liver disease (MAFLD). METHODS: C57BL/6J mouse models of MAFLD induced by high-fat diet feeding for 16 weeks were treated with intraperitoneal injections of STM2457 (50 mg/kg) for 2 weeks. The changes in m(6)A modification level in the liver tissue of the mice were determined with dot-blot hybridization, and the hepatic levels of triglyceride (TG), alanine aminotransferase (ALT) and glutathione aminotransferase (AST) were detected. The histological changes of the liver and changes in insulin resistance and metabolic profile of the mice were evaluated using HE staining, insulin tolerance tests and metabolic cages; transmission electron microscopy (TEM) was employed to examine the changes in mitochondrial morphology. In a HepG2 cell model of steatosis induced by treatment with sodium oleate/sodium palmitate for 48 h, the protective effect of STM2457 (1 μmol/L) on mitochondrial function was assessed by measuring mitochondrial membrane potential using a fluorescence probe (JC-1). RESULTS: The mouse models of MAFLD showed significant elevation of m(6)A modification level in the liver tissues and obviously upregulated mRNA expression of METT3 (P<0.05). Treatment with STM2457 significantly reduced body weight and liver lipid deposition and m(6)A modification levels, increased glucose tolerance and insulin sensitivity, lowered hepatic TG and serum ALT and AST levels, and increased respiratory entropy (RQ) in the mouse models (all P<0.05). HepG2 cells with steatosis exhibited obvious mitochondrial swelling with decreased mitochondrial membrane potential, but the STM2457-treated cells maintained a normal mitochondrial morphology with a higher membrane potential (P<0.05). CONCLUSION: The METTL3 inhibitor STM2457 improves MAFLD by reducing high-fat diet-induced mitochondrial damage in mice.