Liver regeneration after cholestatic damage induced by Rbpj deletion

Liver cholestasis is a chronic liver disease (CLD) which belongs to a major health problem. Cholestasis is characterised by a decrease in bile flow due to impaired secretion by hepatocytes or by obstruction of bile flow through intra- or extrahepatic bile ducts. Thereby cholestasis can induce ductal proliferation, hepatocyte injury and liver fibrosis. Notch signalling promotes the formation and maturation of ductular reactions. We investigated the liver regeneration process in the context of cholestasis induced by disruption of the Notch signalling pathway. Liver-specific deletion of Rbpj, which represents a key regulator of Notch signalling, induces severe cholestasis through impaired IHBD maturation, severe necrosis and increased lethality. Deregulation of the biliary compartment and cholestasis are associated with change of several signalling pathways including the Hippo pathway resulting in upregulation of SOX9, which is associated with transdifferentiation of hepatocytes. SOX9 upregulation in cholestatic liver injury in vitro is independent of Notch signalling. We could comprehensively address that Rbpj depletion is followed by deregulation of YAP/TEAD, which influences transdifferentiation of hepatocytes and thereby contributing to liver regeneration. In this study the liver regeneration process was analyzed in 4 weeks old Rbpj knockout mice and compared to 4 weeks old Rbpj wildtype mice. RNA from whole liver derived from 4 weeks old Rbpj-/- and 4 weeks old Rbpj+/+ mice on a C57BL/6J background was used. Agilent Mouse Gene Expression Microarrays 8x60K were used.