Regulation of bile acid receptor activity.

Many receptors can be activated by bile acids (BAs) and their derivatives. These include nuclear receptors farnesoid X receptor (FXR), pregnane X receptor (PXR), and vitamin D receptor (VDR), as well as membrane receptors Takeda G protein receptor 5 (TGR5), sphingosine-1-phosphate receptor 2 (S1PR2), and cholinergic receptor muscarinic 2 (CHRM2). All of them are implicated in the development of metabolic and immunological diseases in response to endobiotic and xenobiotic exposure. Because epigenetic regulation is critical for organisms to adapt to constant environmental changes, this review article summarizes epigenetic regulation as well as post-transcriptional modification of bile acid receptors. In addition, the focus of this review is on the liver and digestive tract although these receptors may have effects on other organs. Those regulatory mechanisms are implicated in the disease process and critically important in uncovering innovative strategy for prevention and treatment of metabolic and immunological diseases.