Farnesoid X receptor

The farnesoid X receptor (FXR), also known as NR1H4 (nuclear receptor subfamily 1, group H, member 4) is a nuclear hormone receptor with activity similar to that seen in other steroid receptors such as estrogen or progesterone but more similar in form to PPAR, LXR and RXR. FXR is encoded by the gene.

Chenodeoxycholic acid and other bile acids are the natural ligand for FXR and like other steroid receptors, when activated, it translocates to the cell nucleus, forms a dimer (in this case a heterodimer) and binds to hormone response elements on DNA which elicits expression or transrepression of gene products. One of the primary functions of FXR activation is the suppression of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis from cholesterol.