The Inducible G Protein-coupled Receptor edg-1 Signals via the Gi/Mitogen-activated Protein Kinase Pathway

• DOI: 10.1074/jbc.271.19.11272
• Publication Date: 2002-07-26T14:52:05Z
• Authors: Menq-Jer Lee; Mark Evans; Timothy Hla
• Keywords: 0301 basic medicine; Base Sequence; Molecular Sequence Data; G1 Phase; 3T3 Cells; Kidney; Cell Line; Immediate-Early Proteins; Enzyme Activation; Epitopes; Kinetics; Mice; 03 medical and health sciences; GTP-Binding Proteins; Calcium-Calmodulin-Dependent Protein Kinases; Animals; Humans; Amino Acid Sequence; Endothelium, Vascular; Cells, Cultured; DNA Primers; Glutathione Transferase

The edg-1 gene encodes an inducible G protein-coupled receptor (GPR) homologue that is induced during the in vitro differentiation of human endothelial cells. The aim of this study was to investigate the G protein-coupling and -signaling properties of the edg-1 polypeptide. The third cytosolic loop (i3) of edg-1 associates with G(i) alpha and G(o) alpha polypeptides in a guanosine 5'-O-(thiotriphosphate)-sensitive manner. Immunoprecipitation of the edg-1 polypeptide in transfected cells results in the co-precipitation of G(i) alpha 1 and G(i) alpha 3 polypeptides. These data strongly suggest that edg-1 is capable of coupling to the Gi pathway. Overexpression of the edg-1 GPR in human embryonic kidney 293 cells results in the sustained activation of the MAP kinase activity that is blocked by pertussis toxin treatment. Moreover, NIH3T3 cells permanently transfected with edg-1 exhibit enhanced MAP kinase and phospholipase A2 activities. These data suggest that the G(i)/mitogen-activated protein kinase pathway is a major signaling pathway regulated by the orphan receptor edg-1.