title: Regulator of G protein signaling 2 mediates cardiac compensation to pressure overload and antihypertrophic effects of PDE5 inhibition in mice.
abstract: The heart initially compensates for hypertension-mediated pressure overload by enhancing its contractile force and developing hypertrophy without dilation. Gq protein-coupled receptor pathways become activated and can depress function, leading to cardiac failure. Initial adaptation mechanisms to reduce cardiac damage during such stimulation remain largely unknown. Here we have shown that this initial adaptation requires regulator of G protein signaling 2 (RGS2). Mice lacking RGS2 had a normal basal cardiac phenotype, yet responded rapidly to pressure overload, with increased myocardial Gq signaling, marked cardiac hypertrophy and failure, and early mortality. Swimming exercise, which is not accompanied by Gq activation, induced a normal cardiac response, while Rgs2 deletion in Galphaq-overexpressing hearts exacerbated hypertrophy and dilation. In vascular smooth muscle, RGS2 is activated by cGMP-dependent protein kinase (PKG), suppressing Gq-stimulated vascular contraction. In normal mice, but not Rgs2-/- mice, PKG activation by the chronic inhibition of cGMP-selective phosphodiesterase 5 (PDE5) suppressed maladaptive cardiac hypertrophy, inhibiting Gq-coupled stimuli. Importantly, PKG was similarly activated by PDE5 inhibition in myocardium from both genotypes, but PKG plasma membrane translocation was more transient in Rgs2-/- myocytes than in controls and was unaffected by PDE5 inhibition. Thus, RGS2 is required for early myocardial compensation to pressure overload and mediates the initial antihypertrophic and cardioprotective effects of PDE5 inhibitors.
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. etakimo1@jhmi.edu
authors.forename: Eiki
authors.initials: E
authors.lastname: Takimoto
authors.forename: Norimichi
authors.initials: N
authors.lastname: Koitabashi
authors.forename: Steven
authors.initials: S
authors.lastname: Hsu
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Ketner
authors.forename: Manling
authors.initials: M
authors.lastname: Zhang
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nagayama
authors.forename: Djahida
authors.initials: D
authors.lastname: Bedja
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Gabrielson
authors.forename: Robert
authors.initials: R
authors.lastname: Blanton
authors.forename: David P
authors.initials: DP
authors.lastname: Siderovski
authors.forename: Michael E
authors.initials: ME
authors.lastname: Mendelsohn
authors.forename: David A
authors.initials: DA
authors.lastname: Kass
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000517:prevention & control*; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000502:physiology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000502:physiology; D006973:Hypertension / Q000150:complications*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D020710:RGS Proteins / Q000032:analysis / Q000502:physiology*; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology*
chemical_list: D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D020710:RGS Proteins; C105345:Rgs2 protein, mouse; D013450:Sulfones; D000068677:Sildenafil Citrate; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases; C569720:Prkg1 protein, mouse; D043802:GTP-Binding Protein alpha Subunits, Gq-G11