Quercetagetin alleviates liver fibrosis in non-alcoholic fatty liver disease by promoting ferroptosis of hepatic stellate cells through GPX4 ubiquitination.

Abstract

Background: Lang Qing A Ta (Huagan Tongluo Fang, HGTLF) is a Tibetan medicine with significant anti-liver fibrosis effects and good efficacy in the treatment of liver diseases, including non-alcoholic fatty liver disease (NAFLD). Quercetagetin (QG) has been identified as an active ingredient of HGTLF that is absorbed into the blood. This study aims to investigate the role of QG in the anti-liver fibrosis effect of HGTLF in NAFLD.

Methods: CCl₄ injection-induced liver fibrosis and high-fat, high-cholesterol diet-induced non-alcoholic steatohepatitis (NASH) mouse models were established. Transforming growth factor-β1 (TGF-β1)-induced hepatic stellate cells (HSCs) were used as in vitro models. The effect of QG on the stability and degradation pathway of glu-tathione peroxidase 4 (GPX4) protein was investigated.

Results: QG improved liver function and hyperlipidemia in CCl₄-injected mice and NASH mice, and alleviated hepatic lipid deposition and hepatic fibrosis. TGF-β1 treatment promoted the expression of α-smooth muscle actin and fibrosis-related genes, while QG reversed this phenomenon and inhibited HSC activation. QG increased the intracellular labile iron pool and lipid reactive oxygen species in HSCs. Treatment with the ferroptosis inhibitor ferrostatin-1 reversed the inhibitory effect of QG on TGF-β1-induced HSC activation. QG reduced GPX4 protein stability and regulated GPX4 K167 ubiquitination via the membrane-associated ring-CH-type finger 8 (MARCHF8)-mediated ubiquitin-proteasome pathway. Interference with MARCHF8 attenuated the effect of QG and promoted HSC activation induced by TGF-β1.

Conclusion: QG, the active ingredient of HGTLF, can induce ferroptosis of HSCs by targeting the degradation of GPX4 through ubiquitination and inhibit HSC activation, thereby alleviating liver fibrosis in NAFLD.