Fibroblast growth factor 19 (FGF-19) belongs to the large FGF family which has at least 23 members. However, FGF-19, along with FGF-21 and FGF-23, belongs to a subfamily of atypical FGFs where it lacks a conventional heparin-binding motif. Therefore, its signal transduction is mediated by the cofactor βKlotho when interacting with FGFRs 1c, 2c and 3c. Interestingly, FGF-19 can interact directly with FGFR4 in absence of βKlotho. FGF-19 regulates metabolic processes including bile acid, lipid and glucose homeostasis, as well as hepatocyte proliferation. Administration of recombinant FGF-19 to mice decreased cholesterol 7-alpha-hydroxylase (CYP7A1) expression, the rate limiting step in bile acid biosynthesis pathway in the liver.
