title: Independent beta-arrestin 2 and G protein-mediated pathways for angiotensin II activation of extracellular signal-regulated kinases 1 and 2.
abstract: Stimulation of a mutant angiotensin type 1A receptor (DRY/AAY) with angiotensin II (Ang II) or of a wild-type receptor with an Ang II analog ([sarcosine1,Ile4,Ile8]Ang II) fails to activate classical heterotrimeric G protein signaling but does lead to recruitment of beta-arrestin 2-GFP and activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) (maximum stimulation approximately 50% of wild type). This G protein-independent activation of mitogen-activated protein kinase is abolished by depletion of cellular beta-arrestin 2 but is unaffected by the PKC inhibitor Ro-31-8425. In parallel, stimulation of the wild-type angiotensin type 1A receptor with Ang II robustly stimulates ERK1/2 activation with approximately 60% of the response blocked by the PKC inhibitor (G protein dependent) and the rest of the response blocked by depletion of cellular beta-arrestin 2 by small interfering RNA (beta-arrestin dependent). These findings imply the existence of independent G protein- and beta-arrestin 2-mediated pathways leading to ERK1/2 activation and the existence of distinct "active" conformations of a seven-membrane-spanning receptor coupled to each.
authors.affiliation: Howard Hughes Medical Institute and Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Huijun
authors.initials: H
authors.lastname: Wei
authors.forename: Seungkirl
authors.initials: S
authors.lastname: Ahn
authors.forename: Sudha K
authors.initials: SK
authors.lastname: Shenoy
authors.forename: Sadashiva S
authors.initials: SS
authors.lastname: Karnik
authors.forename: László
authors.initials: L
authors.lastname: Hunyady
authors.forename: Louis M
authors.initials: LM
authors.lastname: Luttrell
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lefkowitz
mesh_terms: D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D019390:Arrestins / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
chemical_list: C000605254:ARRB2 protein, human; C000605257:Arrb2 protein, rat; D019390:Arrestins; D017931:DNA Primers; D004791:Enzyme Inhibitors; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D000804:Angiotensin II; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins