title: Differential kinetic and spatial patterns of beta-arrestin and G protein-mediated ERK activation by the angiotensin II receptor.
abstract: The seven-membrane-spanning angiotensin II type 1A receptor activates the mitogen-activated protein kinases extracellular signal-regulated kinases 1 and 2 (ERK1/2) by distinct pathways dependent on either G protein (likely G(q)/G(11)) or beta-arrestin2. Here we sought to distinguish the kinetic and spatial patterns that characterize ERK1/2 activated by these two mechanisms. We utilized beta-arrestin RNA interference, the protein kinase C inhibitor Ro-31-8425, a mutant angiotensin II receptor (DRY/AAY), and a mutant angiotensin II peptide (SII-angiotensin), which are incapable of activating G proteins, to isolate the two pathways in HEK-293 cells. G protein-dependent activation was rapid (peak <2 min), quite transient (t((1/2)) approximately 2 min), and led to nuclear translocation of the activated ERK1/2 as assessed by confocal microscopy. In contrast, beta-arrestin2-dependent activation was slower (peak 5-10 min), quite persistent with little decrement noted out to 90 min, and entirely confined to the cytoplasm. Moreover, ERK1/2 activated via beta-arrestin2 accumulated in a pool of cytoplasmic endosomal vesicles that also contained the internalized receptors and beta-arrestin. Such differential regulation of the temporal and spatial patterns of ERK1/2 activation via these two pathways strongly implies the existence of distinct physiological endpoints.
authors.affiliation: Howard Hughes Medical Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Seungkirl
authors.initials: S
authors.lastname: Ahn
authors.forename: Sudha K
authors.initials: SK
authors.lastname: Shenoy
authors.forename: Huijun
authors.initials: H
authors.lastname: Wei
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lefkowitz
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D019390:Arrestins / Q000378:metabolism*; D002460:Cell Line; D004789:Enzyme Activation; D006801:Humans; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D044140:Receptor, Angiotensin, Type 1; D000071557:beta-Arrestins; D000804:Angiotensin II; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3