FGFR Signaling in Liver Injury and Fibrosis

ABSTRACT Liver fibrosis is a significant cause of mortality worldwide. Factors such as chronic liver injury, infection, metabolic and toxin insults, and genetic factors are associated with the development of liver fibrosis. Rapidly expanding intrahepatic biliary epithelium or ductular reaction with a closely associated highly invasive bridging fibrosis are the characteristic features of advanced liver fibrosis, which has no definite cure. Fibrosis leads to a significant distortion of hepatic function, progresses to liver failure. Therefore, the prevention of fibrosis progression is of paramount importance. Even after tremendous scientific advancements in the area of liver fibrosis, the molecular and cellular mechanisms of how fibrosis progresses to an end-stage liver disease remain a medical enigma. Previously we have shown that Fibroblast growth factor receptors (FGFRs) were highly induced and co-localized to a heterogeneous population of biliary precursors and profibrogenic cells co-expressing Prominin1 (PROM1) with an activated TGF beta signaling in fibrotic livers. Based on the literature and preliminary studies, we hypothesize that FGFRs via its crosstalk with the TGF beta pathway promotes ductular reaction and fibrosis in chronically injured livers. The goals of this application are to elucidate the cell-type-specific role of FGFRs in ductular reaction and fibrosis progression in a setting of chronic liver injury. Specific aims of this proposal are: (1) Identify the mechanisms of FGFRs activation and its significance in liver injury and fibrosis. (2) Elucidate the mechanism by which FGFR signaling in Prom1 expressing cells promote ductular reaction and fibrosis. (3) Identify the mechanism and the significance of FGFR-TGF beta crosstalk in liver fibrosis. Successful completion of the proposed work may identify novel therapeutic targets and FGFR-mediated signaling crosstalk that promotes liver fibrosis progression during chronic liver injury.