Hepatocyte DDIT4 aggravates MASH progression through GPX4-mediated ferroptosis

BACKGROUND & AIMS: Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive liver disease with limited therapeutic options, and the role of ferroptosis in its pathogenesis remains to be fully understood. In this study, we aimed to investigate the action of DNA damage-inducible transcript 4 (DDIT4) in the ferroptosis and regulation of MASH progression. METHODS: The Gene Expression Omnibus database of MASH mice models and ferroptosis database were used to identify crucial ferroptosis related genes in MASH. Hepatic DDIT4 expression was detected in MASH patients, mouse models and hepatocytes. The functional role of DDIT4 was assessed in different diet-induced MASH mice models with hepatocyte-specific DDIT4 overexpression or knockout. RNA-sequencing and immunoprecipitation-mass spectrometry (IP-MS) were performed to determine DDIT4 interacting proteins. Molecular docking was used to explore the potential compound targeting DDIT4. RESULTS: We have discovered significantly elevated DDIT4 levels in mice and patients with MASH, which were positively correlated with MASH severity. Hepatocyte-specific over-expression of DDIT4 aggravated ferroptosis and MASH progression, while DDIT4 deletion alleviated ferroptosis and MASH progression. Mechanistically, DDIT4 decreased glutathione peroxidase 4 (GPX4) expression in an mTORC1 dependent manner. Additionally, DDIT4 interacted with cytosolic GPX4 and inhibited TOM22-mediated mitochondrial translocation, resulting in mitochondrial GPX4 reduction and ferroptosis activation. Importantly, through molecular docking and surface plasmon resonance (SPR), we have identified quercetagetin, a natural flavonoid, as a potential DDIT4-targeting compound. Administration of quercetagetin alleviated hepatic steatosis, inflammation, and fibrosis in MASH mice. CONCLUSIONS: Our study establishes the DDIT4-GPX4-ferroptosis axis as a new regulatory node in MASH progression and highlights DDIT4 as a potential therapeutic target for MASH.