Figure 6.

Mechanisms of bile acid homeostasis. Activation of FXR by CDCA or OCA results in increased expression of small heterodimer partner (SHP) and fibroblast growth factor 19 (FGF‐19), genes that suppress Cholesterol 7α‐hydroxylase (CYP7A1), the rate‐limiting enzyme in the de novo bile acid synthesis pathway. FXR also directly regulates bile acids via induction of the bile acid salt export pump (BSEP), which effluxes bile acids from hepatocytes to bile and heterodimer organic solute transporters, OST _α and OST _β, which transport bile acids form hepatocytes to blood circulation.