Newer variants of progressive familial intrahepatic cholestasis

Figure 3 Schematic representation of role of farnesoid X receptor in hepatocyte. Bile acids are transported into the hepatocyte by NTCP. De novo synthesis of bile acids from cholesterol is mediated by CYP7A1. Bile acids and farnesoid X receptor (FXR) interact and enter the nucleus to promote expression of bile salt export protein and short heterodimer partner (SHP). SHP suppresses expression of NTCP and CYP7A1. FXR also induces FGF-19 in ileal enterocytes which inhibits CYP7A1 via FGFR4. ASBT: Apical sodium bile transporter, BSEP: Bile salt export pump; FGF-19: Fibroblast growth factor-19; FGFR-4: Fibroblast growth factor receptor-4; FXR: Farnesoid X receptor; NTCP: Na+-taurocholate co-transporting polypeptide; OST α/β: Organic solute transporter; RXR: Retinoid X receptor; SHP: Short heterodimer partner.