Targeted Mitochondrial ECSIT Overexpression Attenuates MASH by Increasing OTUD3 Expression

ABSTRACT Mitochondrial dysfunction plays a key role in the pathogenesis of metabolic dysfunction‐associated steatohepatitis (MASH). As is known to play a key role in mitochondria, ECSIT, in relation to oxidized mitochondrial DNA is still unclear. This study examines mitochondrial ECSIT expression in MASH mouse models. Mitochondria‐targeted ECSIT transgenic (ECSIT ^MTG ) mice and wild‐type (WT) controls are fed a high‐fat, high‐cholesterol (HFHC) diet for 16 weeks or a methionine‐ and choline‐deficient (MCD) diet for 8 weeks. Results demonstrate that mitochondrial ECSIT overexpression alleviates diet‐induced MASH phenotypes. Mechanistically, we demonstrate that mitochondrial ECSIT promotes the localization of the deubiquitinase OTUD3 to mitochondria. OTUD3 then stabilizes SIRT3 via deubiquitination, thereby inhibiting mtDNA oxidation and alleviating steatosis‐induced metabolic disorders. Overall, these findings indicate that mitochondrial ECSIT protects against MASH progression by stabilizing SIRT3, suggesting its potential as a therapeutic target.