The SIRT3-DsbA-L-TFAM Axis Suppresses Liver cGAS Signaling and MASH Progression in Male Mice
While mitochondrial dysfunction is implicated in metabolic dysfunction associated steatohepatitis (MASH), the precise underlying mechanisms remain obscure. Here, we identify the SIRT3-DsbA-L-TFAM axis as a crucial suppressor for mitochondrial stress-induced cGAS activation in the hepatocytes, thereby alleviating MASH in mice. SIRT3 facilitates the deacetylation of Disulfide-bond-A oxidoreductase-like protein (DsbA-L) at lysine residues (Lys165, Lys167, and Lys177), which promotes the interaction between DsbA-L and mitochondrial transcription factor A (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-STING 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. Overall design: To investigate whether hepatic STING palys a role in MASH, primary hepatocytes purified from LOXP and liver STING-specific knockout (STINGLKO) mice, and treated with palmitic acid (PA, 0.1 mM) for 24 hours. The hepatocytes were then harvested and subjected to commercial RNA-Seq.