OBJECTIVES: Impaired autophagy is increasingly recognized as a key contributor to the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). However, its underlying molecular mechanisms remain largely undefined. Emerging evidence implicates epigenetic regulators in modulating autophagic pathways in metabolic diseases. Therefore, this study aimed to elucidate the role of a histone methyltransferase, nuclear receptor binding SET domain protein 2 (NSD2), in regulating autophagy and its contribution to MASLD progression.
METHODS: NSD2 expression levels were evaluated in liver tissues from patients with MASLD and mouse models. Functional studies were conducted using hepatocyte-specific Nsd2 knockout and overexpression mouse models, along with cleavage under targets and tagmentation analysis in hepatocyte cell lines. Additionally, the effects of pharmacological NSD2 inhibition using NSC663284 were evaluated in human liver organoids. Autophagy, hepatic steatosis, and related epigenetic changes were assessed through molecular and histological techniques.
RESULTS: NSD2 expression was markedly elevated in both patient livers and murine models, correlating positively with disease severity. Hepatic NSD2 deficiency alleviated diet-induced autophagy impairment and steatosis, while NSD2 overexpression exacerbated these pathologies. Mechanistically, NSD2 epigenetically suppressed TFEB transcription by promoting trimethylation of histone H4 at lysine 20, impairing autophagy. Pharmacological inhibition of NSD2 with NSC663284 similarly alleviated hepatic steatosis in human liver organoids.
CONCLUSION: NSD2 acts as a key epigenetic suppressor of TFEB-mediated autophagy in the liver, promoting lipid accumulation and MASLD progression. Targeting NSD2 represents a promising therapeutic strategy for MASLD.
