title: Differential β-arrestin-dependent conformational signaling and cellular responses revealed by angiotensin analogs.
abstract: The angiotensin type 1 receptor (AT1R) and its octapeptide ligand, angiotensin II (AngII), engage multiple downstream signaling pathways, including those mediated by heterotrimeric guanosine triphosphate-binding proteins (G proteins) and those mediated by β-arrestin. Here, we examined AT1R-mediated Gα(q) and β-arrestin signaling with multiple AngII analogs bearing substitutions at position 8, which is critical for binding to the AT1R and its activation of G proteins. Using assays that discriminated between ligand-promoted recruitment of β-arrestin to the AT1R and its resulting conformational rearrangement, we extend the concept of biased signaling to include the analog's propensity to differentially promote conformational changes in β-arrestin, two responses that were differentially affected by distinct G protein-coupled receptor kinases. The efficacy of AngII analogs in activating extracellular signal-regulated kinases 1 and 2 correlated with the stability of the complexes between β-arrestin and AT1R in endosomes, rather than with the extent of β-arrestin recruitment to the receptor. In vascular smooth muscle cells, the ligand-induced conformational changes in β-arrestin correlated with whether the ligand promoted β-arrestin-dependent migration or proliferation. Our data indicate that biased signaling not only occurs between G protein- and β-arrestin-mediated pathways but also occurred at the level of the AT1R and β-arrestin, such that different AngII analogs selectively engaged distinct β-arrestin conformations, which led to specific signaling events and cell responses.
authors.affiliation: 1McGill University Health Center Research Institute, Department of Medicine, McGill University, Montreal, Quebec H3A 2B2, Canada.
authors.forename: Brandon
authors.initials: B
authors.lastname: Zimmerman
authors.forename: Alexandre
authors.initials: A
authors.lastname: Beautrait
authors.forename: Benjamin
authors.initials: B
authors.lastname: Aguila
authors.forename: Ricardo
authors.initials: R
authors.lastname: Charles
authors.forename: Emanuel
authors.initials: E
authors.lastname: Escher
authors.forename: Audrey
authors.initials: A
authors.lastname: Claing
authors.forename: Michel
authors.initials: M
authors.lastname: Bouvier
authors.forename: Stéphane A
authors.initials: SA
authors.lastname: Laporte
mesh_terms: D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D011992:Endosomes / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D046912:Multiprotein Complexes; D044140:Receptor, Angiotensin, Type 1; D000071557:beta-Arrestins; D000804:Angiotensin II; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3