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G??-independent recruitment of G-protein coupled receptor kinase 2 drives tumor necrosis factor ?-induced cardiac ?-adrenergic receptor dysfunction.

ABSTRACT: Proinflammatory cytokine tumor necrosis factor-? (TNF?) induces ?-adrenergic receptor (?AR) desensitization, but mechanisms proximal to the receptor in contributing to cardiac dysfunction are not known.Two different proinflammatory transgenic mouse models with cardiac overexpression of myotrophin (a prohypertrophic molecule) or TNF? showed that TNF? alone is sufficient to mediate ?AR desensitization as measured by cardiac adenylyl cyclase activity. M-mode echocardiography in these mouse models showed cardiac dysfunction paralleling ?AR desensitization independent of sympathetic overdrive. TNF?-mediated ?AR desensitization that precedes cardiac dysfunction is associated with selective upregulation of G-protein coupled receptor kinase 2 (GRK2) in both mouse models. In vitro studies in ?2AR-overexpressing human embryonic kidney 293 cells showed significant ?AR desensitization, GRK2 upregulation, and recruitment to the ?AR complex following TNF?. Interestingly, inhibition of phosphoinositide 3-kinase abolished GRK2-mediated ?AR phosphorylation and GRK2 recruitment on TNF?. Furthermore, TNF?-mediated ?AR phosphorylation was not blocked with ?AR antagonist propranolol. Additionally, TNF? administration in transgenic mice with cardiac overexpression of G??-sequestering peptide ?ARK-ct could not prevent ?AR desensitization or cardiac dysfunction showing that GRK2 recruitment to the ?AR is G?? independent. Small interfering RNA knockdown of GRK2 resulted in the loss of TNF?-mediated ?AR phosphorylation. Consistently, cardiomyocytes from mice with cardiac-specific GRK2 ablation normalized the TNF?-mediated loss in contractility, showing that TNF?-induced ?AR desensitization is GRK2 dependent.TNF?-induced ?AR desensitization is mediated by GRK2 and is independent of G??, uncovering a hitherto unknown cross-talk between TNF? and ?AR function, providing the underpinnings of inflammation-mediated cardiac dysfunction.

SUBMITTER: Vasudevan NT

PROVIDER: S-EPMC3874808 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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Gβγ-independent recruitment of G-protein coupled receptor kinase 2 drives tumor necrosis factor α-induced cardiac β-adrenergic receptor dysfunction.

Vasudevan Neelakantan T NT Mohan Maradumane L ML Gupta Manveen K MK Martelli Elizabeth E EE Hussain Afshan K AK Qin Yilu Y Chandrasekharan Unni M UM Young David D Feldman Arthur M AM Sen Subha S Dorn Gerald W GW Dicorleto Paul E PE Naga Prasad Sathyamangla V SV

Circulation 20130619 4

<h4>Background</h4>Proinflammatory cytokine tumor necrosis factor-α (TNFα) induces β-adrenergic receptor (βAR) desensitization, but mechanisms proximal to the receptor in contributing to cardiac dysfunction are not known.<h4>Methods and results</h4>Two different proinflammatory transgenic mouse models with cardiac overexpression of myotrophin (a prohypertrophic molecule) or TNFα showed that TNFα alone is sufficient to mediate βAR desensitization as measured by cardiac adenylyl cyclase activity. ...[more]

PMID: 23785004

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Project description:Aims Myocardial infarction (MI) is the most common cause of heart failure (HF) worldwide. G protein-coupled receptor kinase 5 (GRK5) is upregulated in failing human myocardium and promotes maladaptive cardiac hypertrophy in animal models. However, the role of GRK5 in ischemic heart disease is still unknown. In this study, we evaluated whether myocardial GRK5 plays a critical role post-MI in mice and included the examination of specific cardiac immune and inflammatory responses.Methods and results Cardiomyocyte-specific GRK5 overexpressing transgenic mice (TgGRK5) and non-transgenic littermate control (NLC) mice as well as cardiomyocyte-specific GRK5 knockout mice (GRK5cKO) and wild type (WT) were subjected to MI and, functional as well as structural changes together with outcomes were studied. TgGRK5 post-MI mice showed decreased cardiac function, augmented left ventricular dimension and decreased survival rate compared to NLC post-MI mice. Cardiac hypertrophy and fibrosis as well as fetal gene expression were increased post-MI in TgGRK5 compared to NLC mice. In TgGRK5 mice, GRK5 elevation produced immuno-regulators that contributed to the elevated and long-lasting leukocyte recruitment into the injured heart and ultimately to chronic cardiac inflammation. We found an increased presence of pro-inflammatory neutrophils and macrophages as well as neutrophils, macrophages and T-lymphocytes at 4-days and 8-weeks respectively post-MI in TgGRK5 hearts. Conversely, GRK5cKO mice were protected from ischemic injury and showed reduced early immune cell recruitment (predominantly monocytes) to the heart, improved contractility and reduced mortality compared to WT post-MI mice. Interestingly, cardiomyocyte-specific GRK2 transgenic mice did not share the same phenotype of TgGRK5 mice and did not have increased cardiac leukocyte migration and cytokine or chemokine production post-MI.Conclusions Our study shows that myocyte GRK5 has a crucial and GRK-selective role on the regulation of leucocyte infiltration into the heart, cardiac function and survival in a murine model of post-ischemic HF, supporting GRK5 inhibition as a therapeutic target for HF.

Project description:Hyperaldosteronism alters cardiac function, inducing adverse left ventricle (LV) remodeling either via increased fibrosis deposition, mitochondrial dysfunction, or both. These harmful effects are due, at least in part, to the activation of the G protein-coupled receptor kinase 2 (GRK2). In this context, we have previously reported that this kinase dysregulates both β-adrenergic receptor (βAR) and insulin (Ins) signaling. Yet, whether aldosterone modulates cardiac Ins sensitivity and βAR function remains untested. Nor is it clear whether GRK2 has a role in this modulation, downstream of aldosterone. Here, we show in vitro, in 3T3 cells, that aldosterone impaired insulin signaling, increasing the negative phosphorylation of insulin receptor substrate 1 (ser307pIRS1) and reducing the activity of Akt. Similarly, aldosterone prevented the activation of extracellular signal-regulated kinase (ERK) and the production of cyclic adenosine 3',5'-monophosphate (cAMP) in response to the β1/β2AR agonist, isoproterenol. Of note, all of these effects were sizably reduced in the presence of GRK2-inhibitor CMPD101. Next, in wild-type (WT) mice undergoing chronic infusion of aldosterone, we observed a marked GRK2 upregulation that was paralleled by a substantial β1AR downregulation and augmented ser307pIRS1 levels. Importantly, in keeping with the current in vitro data, we found that aldosterone effects were wholly abolished in cardiac-specific GRK2-knockout mice. Finally, in WT mice that underwent 4-week myocardial infarction (MI), we observed a substantial deterioration of cardiac function and increased LV dilation and fibrosis deposition. At the molecular level, these effects were associated with a significant upregulation of cardiac GRK2 protein expression, along with a marked β1AR downregulation and increased ser307pIRS1 levels. Treating MI mice with spironolactone prevented adverse aldosterone effects, blocking GRK2 upregulation, and thus leading to a marked reduction in cardiac ser307pIRS1 levels while rescuing β1AR expression. Our study reveals that GRK2 activity is a critical player downstream of the aldosterone signaling pathway; therefore, inhibiting this kinase is an attractive strategy to prevent the cardiac structural disarray and dysfunction that accompany any clinical condition accompanied by hyperaldosteronism.

Dataset Information

G??-independent recruitment of G-protein coupled receptor kinase 2 drives tumor necrosis factor ?-induced cardiac ?-adrenergic receptor dysfunction.

Publications

Gβγ-independent recruitment of G-protein coupled receptor kinase 2 drives tumor necrosis factor α-induced cardiac β-adrenergic receptor dysfunction.

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