The SIRT3-DsbA-L-TFAM axis restrains cGAS-driven metabolic dysfunction-associated steatohepatitis in male mice

Whereas mitochondrial dysfunction is implicated in metabolic dysfunction-associated steatohepatitis (MASH), the precise underlying mechanisms remain obscure. Here, we identify the Sirtuin 3 (SIRT3)-Disulfide-bond-A oxidoreductase-like protein (DsbA-L)-Mitochondrial Transcription Factor A (TFAM) axis as a crucial suppressor for mitochondrial stress-induced cyclic GMP-AMP synthase (cGAS) activation in hepatocytes, thereby alleviating MASH in mice. SIRT3 facilitates the deacetylation of DsbA-L at lysine residues (Lys¹⁶⁵, Lys¹⁶⁷, and Lys¹⁷⁷), which promotes the interaction between DsbA-L and TFAM, essential for the preservation of mitochondrial integrity and function. Hepatocyte-specific knockout of SIRT3 or DsbA-L in male mice promoted mitochondrial DNA release into the cytosol, resulting in activation of the cGAS pathway and exacerbation of MASH characteristics. Conversely, hepatocyte-specific knockout of cGAS or overexpression of DsbA-L mitigated diet- and SIRT3 deficiency-induced MASH progression. Our study underscores the clinical significance of targeting SIRT3 and cGAS as pivotal therapeutic avenues to inhibit the progression of MASH.