Sex-determining Region Y Gene Promotes Liver Fibrosis and Accounts for Sexual Dimorphism in Its Pathophysiology.

Background & Aims: Men are more prone to develop and die from liver fibrosis than women. In this study, we aim to investigate how sex -determining region Y gene (SRY) in hepatocytes promotes liver fibrosis. Methods: Hepatocyte-specific Sry knock -in (KI), Sry knockout (KO), and Sry KI with platelet -derived growth factor receptor a ( Pdgfra ) KO mice were generated. Liver fibrosis was induced in mice by bile duct ligation for 2 weeks or carbon tetrachloride treatment for 6 weeks. In addition, primary hepatocytes, hepatic stellate cells (HSCs), and immortalized cell lines were used for in vitro studies and mechanistic investigation. Results: Compared to females, the severity of toxin- or cholestasis-induced liver fibrosis is similarly increased in castrated and uncastrated male mice. Among all Y chromosome -encoded genes, SRY was the most significantly upregulated and consistently increased gene in fibrotic/cirrhotic livers in male patients and in mouse models. Sry KI mice developed exacerbated liver fibrosis, whereas Sry KO mice had alleviated liver fibrosis, compared to age- and sex -matched control mice after bile duct ligation or administration of carbon tetrachloride. Mechanistically, both our in vivo and in vitro studies illustrated that SRY in hepatocytes can transcriptionally regulate Pdgfra expression, and promote HMGB1 (high mobility group box 1) release and subsequent HSC activation. Pdgfra KO or treatment with the SRY inhibitor DAX1 in Sry KI mice abolished SRY-induced HMGB1 secretion and liver fibrosis. Conclusions: SRY is a strong pro -fibrotic factor and accounts for the sex disparity observed in liver fibrosis, suggesting its critical role as a potentially sex -specific therapeutic target for prevention and treatment of the disease. (c) 2024 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.