Free Fatty Acid Receptors and Their Physiological Role in Metabolic Regulation

Free fatty acids (FFAs) are not only essential nutrient components, but they also function as signaling molecules in various physiological processes. In the progression of genomic analysis, many orphan G-protein coupled receptors (GPCRs) are found. Recently, GPCRs deorphanizing strategy successfully identified multiple receptors for FFAs. In these FFA receptors (FFARs), GPR40 (FFAR1) and GPR120 are activated by medium- to long- chain FFAs. GPR40 is expressed mainly in pancreatic beta-cell and mediates insulin secretion, whereas GPR120 is expressed abundantly in the intestine and regulates the secretion of cholecystokinin (CCK) and glucagons-like peptide-1 (GLP-1), it promotes insulin secretion. Due to these biological activity, GPR40 and GPR120 are potential drug target for type 2 diabetes and selective ligands have been developed. In this review, we provide recent development in the field and discuss their physiological roles and their potential as drug targets.