Bile Acids and TGR5 (Gpbar1) Signaling

TGR5 (Gpbar1, M-BAR) is a Gs protein-coupled, cell surface receptor responsive to bile acids as well as various steroid hormones. Ligand binding to TGR5 activates adenylate cyclase, triggers an elevation of intracellular cyclic AMP (cAMP) levels and activates further downstream signaling pathways. Moreover, TGR5 can modulate signaling of Src kinases, mitogen-activated protein (MAP) kinases, and the epidermal growth factor receptor (EGFR) independent of adenylate cyclase activation.