Epidermal growth factor signaling protects from cholestatic liver injury and fibrosis

We have demonstrated that the signal transducer and activator of transcription 3 (STAT3) protects from cholestatic liver injury. Specific ablation of STAT3 in hepatocytes and cholangiocytes (STAT3) aggravated liver damage and fibrosis in the Mdr2 (multidnig resistance 2) mouse model for cholestatic disease. Upregulation of bile acid biosynthesis genes and downregulation of epidermal growth factor receptor (EGFR) expression were observed in STAT3Al1c Mdr2 mice but the functional consequences of these processes in cholestatic liver injury remained unclear. Here, we show normal canalicular architecture and bile flow but increased amounts of bile acids in the bile of STAT3Al1c Mdr2 mice. Moreover. STN13-deficient hepatocytes displayed increased sensitivity to bile acid -induced apoptosis in vitro. Since EGFR signaling has been reported to protect hepatocytes from bile acid induced apoptosis, we generated mice with hepatocytel cholangiocyte-specific ablation of EGFR (EGFR') and crossed them to Mdr2 mice. Importantly, deletion of EGFR phenocopied deletion of STAI3 and led to aggravated liver damage, liver fibrosis, and hyperproliferation of K19+ cholangiocytes. Our data demonstrate hepatoprotective functions of the STAT3-EGFR signaling axis in cholestatic liver disease.