title: Beta-arrestin- and c-Src-dependent degradation of G-protein-coupled receptor kinase 2.
abstract: G-protein-coupled receptor kinase 2 (GRK2) plays a key role in the regulation of G-protein-coupled receptors (GPCRs). GRK2 expression is altered in several pathological conditions, but the molecular mechanisms that modulate GRK2 cellular levels are largely unknown. We recently have described that GRK2 is degraded rapidly by the proteasome pathway. This process is enhanced by GPCR stimulation and is severely impaired in a GRK2 mutant that lacks kinase activity (GRK2-K220R). In this report, we find that beta-arrestin function and Src-mediated phosphorylation of GRK2 are critically involved in GRK2 proteolysis. Overexpression of beta-arrestin triggers GRK2-K220R degradation based on its ability to recruit c-Src, since this effect is not observed with beta-arrestin mutants that display an impaired c-Src interaction. The presence of an inactive c-Src mutant or of tyrosine kinase inhibitors strongly inhibits co-transfected or endogenous GRK2 turnover, respectively, and a GRK2 mutant with impaired phosphorylation by c-Src shows a markedly retarded degradation. This pathway for the modulation of GRK2 protein stability puts forward a new feedback mechanism for regulating GRK2 levels and GPCR signaling.
authors.affiliation: Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Penela
authors.forename: A
authors.initials: A
authors.lastname: Elorza
authors.forename: S
authors.initials: S
authors.lastname: Sarnago
authors.forename: F
authors.initials: F
authors.lastname: Mayor
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000502:physiology*; D019556:COS Cells; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D034281:Dynamins; D054769:G-Protein-Coupled Receptor Kinase 2; D020558:GTP Phosphohydrolases / Q000235:genetics; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D009154:Mutation; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D017368:Protein Prenylation; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D051552:beta-Adrenergic Receptor Kinases; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D000071557:beta-Arrestins; D019000:Phosphotyrosine; D016392:Proto-Oncogene Proteins pp60(c-src); D017868:Cyclic AMP-Dependent Protein Kinases; C496567:GRK2 protein, human; D051552:beta-Adrenergic Receptor Kinases; D054769:G-Protein-Coupled Receptor Kinase 2; D020558:GTP Phosphohydrolases; D034281:Dynamins