Fig 1.

Bile acids and hepatocyte cell signalling. (A.1): In the liver bile acids activate NR involved bile acid synthesis, uptake and detoxification. In addition to FXR, a master gene that inhibits their uptake and synthesis, bile acids activate PXR, CAR and VDR. These NRs regulate the expression/activity of phase I and II detoxification enzymes and the induction of canalicular and alternative basolateral transporters (A.2). (B). In the muscle cells (human) and brown adipose tissue (mouse) bile acids activate a cell membrane receptor, TGR-5 (M-BAR), involved in regulation of thermogenesis and basal energy expenditure.