Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent disorder characterized by excessive hepatic lipid accumulation, frequently progressing to steatohepatitis, fibrosis, and cirrhosis. Transcription factor EB (TFEB) coordinates lysosomal biogenesis, autophagy, and lipid catabolism, and therefore represents a potential therapeutic target; however, safe and direct strategies for selectively enhancing hepatic TFEB activity remain limited. Here, liver-targeted lipid nanoparticles (LNPs) were developed to deliver mRNAs encoding wild-type TFEB or the constitutively active TFEB S211A mutant, and their efficacy was evaluated in cellular and choline-deficient, L-amino acid-defined high-fat diet (CDAHFD)-induced mouse models of MASLD. LNP-mediated delivery increased hepatic TFEB expression, enhanced autophagic flux, and reprogrammed metabolic pathways toward fatty acid oxidation (e.g., CPT1A and ACOX1) while suppressing the expression of lipogenic genes (e.g., FASN, ACC, and SREBP1). Consequently, targeted TFEB mRNA therapy significantly reduced hepatic triglyceride content, attenuated steatosis, lowered MASLD activity scores, and decreased fibrotic remodeling. Mechanistically, transcriptomic profiling, ChIP-qPCR, promoter-reporter assays, and targeted knockdown models indicated that TFEB exerts its protective effects against lipid accumulation at least partly by transcriptionally activating the fibroblast growth factor 21 (FGF21) signaling pathway. Collectively, these findings establish LNP-mediated TFEB mRNA delivery as a useful preclinical approach for investigating hepatic biology and provide a targeted, transient, and non-integrating genetic strategy with potential for the treatment of MASLD.
