Intestinal FXR and TGR5 signaling in metabolic regulation

摘要

Bile acids play a critical role in regulation of glucose, lipid and energy metabolisms through activating the nuclear bile acid receptor farnesoid X receptor (FXR) and membrane G protein-coupled bile acid receptor-1 (Gpbar-1 aka TGR5) signaling. Paradoxical roles of FXR in regulation of glucose and lipid metabolism and metabolic disorder have been reported recently. Activation or inhibition of intestinal FXR signaling have been shown to improve insulin and glucose sensitivity and energy metabolism to prevent diabetes, obesity and non-alcoholic fatty liver disease (NAFLD). TGR5 has an anti-inflammatory function in the intestine and stimulates glucagon-like peptide-1 (GLP-1) secretion in the intestine to stimulate insulin secretion from the pancreas. The role of TGR5 in metabolism and metabolic regulation is not clear and warrants further study. FXR and TGR5 are co-expressed in the ileum and colon. These two bile acid-activated receptors may cooperate to stimulate GLP-1 secretion and improve hepatic metabolism. FXR and TGR5 dual agonists may have therapeutic potential for treating diabetes and NAFLD.