Serpina3c Deficiency Induced Necroptosis Promotes Non-Alcoholic Steatohepatitis Through β-Catenin/Foxo1/TLR4 Signaling

Abstract

Background: Hepatocyte death and liver inflammation have been recognized as central characteristics of nonalcoholic steatohepatitis (NASH); however, the underlying molecular mechanism remains elusive. The aim of this study is to determine the precise role of serpina3c in the progression of NASH.Methods: Male Apoe-/-/serpina3c-/- double knockout (DKO) and Apoe-/- mice were fed a high-fat diet (HFD) for 12 weeks to induce NASH. Several markers of steatosis and inflammation were evaluated. In vitro cell models induced by palmitic acid (PA) treatment were used to evaluate the beneficial effect of serpina3c on necroptosis and the underlying molecular mechanism.Results: Compared with Apoe-/- mice, DKO mice exhibited a significantly exacerbated NASH phenotype that included hepatic steatosis, inflammation, fibrosis and liver damage, and increased hepatic triglyceride contents. We also indicated that the expression of the receptor-interacting protein 3 (RIP3) and phosphorylated mixed lineage kinase domain-like (MLKL) was increased in DKO mice. Our results found that serpina3c knockdown promoted necroptosis and lipid droplet formation under conditions of lipotoxicity in vitro. However, these phenomena were reversed by the overexpression of serpina3c. Mechanistically, downregulation of serpina3c expression promoted Foxo1 and β-catenin expression, and Foxo1 and β-catenin colocalized in the nucleus under conditions of lipotoxicity, consequently upregulating the expression of Toll-like receptor4 (TLR4). However, disruption of the Foxo1-β/catenin by Foxo1 and β-catenin inhibitors decreased TLR4 expression and ameliorated hepatic necroptosis in vitro.Conclusion: Serpina3c plays a protective role against the progression of NASH by inhibiting necroptosis. Serpina3c, a Wnt/β-catenin inhibitor, inhibits necroptosis via β-catenin/Foxo1 by inhibiting TLR4 expression.