Role of the autophagy inhibiting molecule “Rubicon” in the pathogenesis of cholestatic liver injury in animal models

Abstract

Backgrounds & aims: Autophagy is a vital cell process for nutrient provision and waste removal. It is mainly regulated by the mTOR pathways. However, in the liver autophagy can be influenced by bile acids and in cholestatic conditions. Our lab discovered that cholestasis impairs autophagy via bile acid activated FXR, which upregulates "Rubicon", an autophagy inhibitor. We hypothesized that inhibiting "Rubicon" could be a potential rescue mechanism for hepatocytes in cholestatic liver conditions. Methods: We measured bile flow in wildtype and Rubicon KO mice to determine potential effects of Rubicon on bile formation. We determined cholestatic liver injury in wildtype and Rubicon KO mice subjected to common bile duct ligation (CBDL), a model of total bile duct obstruction, at two different times (3 and 7 day). Finally, we determined the cholestatic phenotype and mechanisms of injury in wildtype, Mdr2-KO - a model for sclerosing cholangitis - and Mdr2-Rubicon double KO mice (DKO). From these mice we comprehensively analysed inflammatory liver injury, fibrosis, cholestasis, and autophagy on serum, mRNA and protein levels. Moreover, we performed immunohistochemical staining to visualize potential changes on hepatocytes. Results: Bile flow is not affected by a deletion of Rubicon. In CBDL mice Rubicon deletion did not affect cholestatic liver injury. In the Mdr2-KO model resembling a chronic cholangiopathy the deletion of Rubicon shows a significant benefit on serum markers of liver injury. DKO mice had less inflammation and less fibrosis. However, these changes were only significant in female mice. Conclusion: Our data show that Rubicon deletion may be beneficial in chronic cholestatic conditions, particularly in female mice, which exhibit a more severe phenotype in the Mdr2-KO model compared to male mice. Targeting Rubicon may present a potential new therapeutical target for chronic cholestatic conditions.

Datum der Bewilligung	2024
Originalsprache	Englisch
Gradverleihende Hochschule	Medizinische Universität Graz
Betreuer/-in	Martin Wagner (Betreuer*in) & Lukas Michael Gulden (Mitbetreuer*in)