title: Inhibition of receptor-localized PI3K preserves cardiac beta-adrenergic receptor function and ameliorates pressure overload heart failure.
abstract: beta-Adrenergic receptor (betaAR) downregulation and desensitization are hallmarks of the failing heart. However, whether abnormalities in betaAR function are mechanistically linked to the cause of heart failure is not known. We hypothesized that downregulation of cardiac betaARs can be prevented through inhibition of PI3K activity within the receptor complex, because PI3K is necessary for betaAR internalization. Here we show that in genetically modified mice, disrupting the recruitment of PI3K to agonist-activated betaARs in vivo prevents receptor downregulation in response to chronic catecholamine administration and ameliorates the development of heart failure with pressure overload. Disruption of PI3K/betaAR colocalization is required to preserve betaAR signaling, since deletion of a single PI3K isoform (PI3Kgamma knockout) is insufficient to prevent the recruitment of other PI3K isoforms and subsequent betaAR downregulation with catecholamine stress. These data demonstrate a specific role for receptor-localized PI3K in the regulation of betaAR turnover and show that abnormalities in betaAR function are associated with the development of heart failure. Thus, a strategy that blocks the membrane translocation of PI3K and leads to the inhibition of betaAR-localized PI3K activity represents a novel therapeutic approach to restore normal betaAR signaling and preserve cardiac function in the pressure overloaded failing heart.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Nienaber
authors.forename: Hideo
authors.initials: H
authors.lastname: Tachibana
authors.forename: Sathyamangla V
authors.initials: SV
authors.lastname: Naga Prasad
authors.forename: Giovanni
authors.initials: G
authors.lastname: Esposito
authors.forename: Dianqing
authors.initials: D
authors.lastname: Wu
authors.forename: Lan
authors.initials: L
authors.lastname: Mao
authors.forename: Howard A
authors.initials: HA
authors.lastname: Rockman
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000209:etiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D006333:Heart Failure / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021381:Protein Transport; D011943:Receptors, Adrenergic, beta / Q000032:analysis / Q000502:physiology*; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D007545:Isoproterenol; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011943:Receptors, Adrenergic, beta; D051552:beta-Adrenergic Receptor Kinases