title: Essential role for G protein-coupled receptor endocytosis in the activation of mitogen-activated protein kinase.
abstract: The classical paradigm for G protein-coupled receptor (GPCR) signal transduction involves the agonist-dependent interaction of GPCRs with heterotrimeric G proteins at the plasma membrane and the subsequent generation, by membrane-localized effectors, of soluble second messengers or ion currents. Termination of GPCR signals follows G protein-coupled receptor kinase (GRK)- and beta-arrestin-mediated receptor uncoupling and internalization. Here we show that these paradigms are inadequate to account for GPCR-mediated, Ras-dependent activation of the mitogen-activated protein (MAP) kinases Erk1 and -2. In HEK293 cells expressing dominant suppressor mutants of beta-arrestin or dynamin, beta2-adrenergic receptor-mediated activation of MAP kinase is inhibited. The inhibitors of receptor internalization specifically blocked Raf-mediated activation of MEK. Plasma membrane-delimited steps in the GPCR-mediated activation of the MAP kinase pathway, such as tyrosine phosphorylation of Shc and Raf kinase activation by Ras, are unaffected by inhibitors of receptor internalization. Thus, GRKs and beta-arrestins, which uncouple GPCRs and target them for internalization, function as essential elements in the GPCR-mediated MAP kinase signaling cascade.
authors.affiliation: Howard Hughes Medical Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Daaka
authors.forename: L M
authors.initials: LM
authors.lastname: Luttrell
authors.forename: S
authors.initials: S
authors.lastname: Ahn
authors.forename: G J
authors.initials: GJ
authors.lastname: Della Rocca
authors.forename: S S
authors.initials: SS
authors.lastname: Ferguson
authors.forename: M G
authors.initials: MG
authors.lastname: Caron
authors.forename: R J
authors.initials: RJ
authors.lastname: Lefkowitz
mesh_terms: D019390:Arrestins / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D034281:Dynamins; D004705:Endocytosis; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D018343:Receptors, Adrenergic, beta-2; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D011994:Recombinant Proteins; D000071557:beta-Arrestins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D034281:Dynamins