title: β-arrestin-biased signaling through the β2-adrenergic receptor promotes cardiomyocyte contraction.
abstract: β-adrenergic receptors (βARs) are critical regulators of acute cardiovascular physiology. In response to elevated catecholamine stimulation during development of congestive heart failure (CHF), chronic activation of Gs-dependent β1AR and Gi-dependent β2AR pathways leads to enhanced cardiomyocyte death, reduced β1AR expression, and decreased inotropic reserve. β-blockers act to block excessive catecholamine stimulation of βARs to decrease cellular apoptotic signaling and normalize β1AR expression and inotropy. Whereas these actions reduce cardiac remodeling and mortality outcomes, the effects are not sustained. Converse to G-protein-dependent signaling, β-arrestin-dependent signaling promotes cardiomyocyte survival. Given that β2AR expression is unaltered in CHF, a β-arrestin-biased agonist that operates through the β2AR represents a potentially useful therapeutic approach. Carvedilol, a currently prescribed nonselective β-blocker, has been classified as a β-arrestin-biased agonist that can inhibit basal signaling from βARs and also stimulate cell survival signaling pathways. To understand the relative contribution of β-arrestin bias to the efficacy of select β-blockers, a specific β-arrestin-biased pepducin for the β2AR, intracellular loop (ICL)1-9, was used to decouple β-arrestin-biased signaling from occupation of the orthosteric ligand-binding pocket. With similar efficacy to carvedilol, ICL1-9 was able to promote β2AR phosphorylation, β-arrestin recruitment, β2AR internalization, and β-arrestin-biased signaling. Interestingly, ICL1-9 was also able to induce β2AR- and β-arrestin-dependent and Ca(2+)-independent contractility in primary adult murine cardiomyocytes, whereas carvedilol had no efficacy. Thus, ICL1-9 is an effective tool to access a pharmacological profile stimulating cardioprotective signaling and inotropic effects through the β2AR and serves as a model for the next generation of cardiovascular drug development.
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107;
authors.forename: Richard
authors.initials: R
authors.lastname: Carr
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107;
authors.forename: Justin
authors.initials: J
authors.lastname: Schilling
authors.affiliation: Department of Pharmacology, Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140;
authors.forename: Jianliang
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Pharmacology, Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140;
authors.forename: Rhonda L
authors.initials: RL
authors.lastname: Carter
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305;
authors.forename: Yang
authors.initials: Y
authors.lastname: Du
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107;
authors.forename: Sungsoo M
authors.initials: SM
authors.lastname: Yoo
authors.affiliation: Department of Pharmacology, Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140;
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Traynham
authors.affiliation: Department of Pharmacology, Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140;
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Koch
authors.affiliation: Department of Medicine, Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140.
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Cheung
authors.affiliation: Department of Pharmacology, Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140;
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Tilley
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107; Jeffrey.Benovic@jefferson.edu.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Benovic
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology* / Q000627:therapeutic use; D000077261:Carvedilol; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D057809:HEK293 Cells; D006333:Heart Failure / Q000188:drug therapy*; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology* / Q000627:therapeutic use; D051379:Mice; D009200:Myocardial Contraction / Q000187:drug effects*; D032383:Myocytes, Cardiac / Q000187:drug effects*; D061251:Primary Cell Culture; D011412:Propanolamines / Q000494:pharmacology* / Q000627:therapeutic use; D011487:Protein Conformation / Q000187:drug effects; D000071557:beta-Arrestins / Q000819:agonists
chemical_list: D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; C000625023:ICL1-9 pepducin; D055666:Lipopeptides; D011412:Propanolamines; D000071557:beta-Arrestins; D000077261:Carvedilol; C026777:ICI 118551
keywords: GPCR; arrestin; carvedilol; heart failure; pepducin