Subject(s)
Genetic Therapy/methods , Heart Failure/metabolism , Myocardial Contraction/physiology , Myocardium/metabolism , Stroke Volume/physiology , Ventricular Remodeling , beta-Arrestin 1/therapeutic use , Biopsy , Heart Failure/physiopathology , Heart Failure/therapy , Humans , Myocardium/pathology , beta-Arrestin 1/metabolismABSTRACT
Heart failure is the leading cause of death in the Western world, and new and innovative treatments are needed. The GPCR (G protein-coupled receptor) adapter proteins ßarr (ß-arrestin)-1 and ßarr-2 are functionally distinct in the heart. ßarr1 is cardiotoxic, decreasing contractility by opposing ß1AR (adrenergic receptor) signaling and promoting apoptosis/inflammation post-myocardial infarction (MI). Conversely, ßarr2 inhibits apoptosis/inflammation post-MI but its effects on cardiac function are not well understood. Herein, we sought to investigate whether ßarr2 actually increases cardiac contractility. Via proteomic investigations in transgenic mouse hearts and in H9c2 rat cardiomyocytes, we have uncovered that ßarr2 directly interacts with SERCA2a (sarco[endo]plasmic reticulum Ca2+-ATPase) in vivo and in vitro in a ß1AR-dependent manner. This interaction causes acute SERCA2a SUMO (small ubiquitin-like modifier)-ylation, increasing SERCA2a activity and thus, cardiac contractility. ßarr1 lacks this effect. Moreover, ßarr2 does not desensitize ß1AR cAMP-dependent procontractile signaling in cardiomyocytes, again contrary to ßarr1. In vivo, post-MI heart failure mice overexpressing cardiac ßarr2 have markedly improved cardiac function, apoptosis, inflammation, and adverse remodeling markers, as well as increased SERCA2a SUMOylation, levels, and activity, compared with control animals. Notably, ßarr2 is capable of ameliorating cardiac function and remodeling post-MI despite not increasing cardiac ßAR number or cAMP levels in vivo. In conclusion, enhancement of cardiac ßarr2 levels/signaling via cardiac-specific gene transfer augments cardiac function safely, that is, while attenuating post-MI remodeling. Thus, cardiac ßarr2 gene transfer might be a novel, safe positive inotropic therapy for both acute and chronic post-MI heart failure.
Subject(s)
Cardiotonic Agents , Heart Failure , Myocardial Contraction , Myocardial Infarction , Myocytes, Cardiac , Ventricular Remodeling , beta-Arrestin 2 , Animals , Apoptosis/drug effects , Apoptosis/physiology , Cardiotonic Agents/metabolism , Cardiotonic Agents/pharmacology , Cells, Cultured , Disease Models, Animal , Gene Transfer Techniques , Heart Failure/etiology , Heart Failure/metabolism , Heart Failure/prevention & control , Humans , Mice , Myocardial Contraction/drug effects , Myocardial Contraction/physiology , Myocardial Infarction/complications , Myocardial Infarction/metabolism , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/physiology , Rats , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Signal Transduction , Stroke Volume , Ventricular Remodeling/drug effects , Ventricular Remodeling/physiology , beta-Arrestin 2/metabolism , beta-Arrestin 2/pharmacologyABSTRACT
The known angiotensin II (AngII) physiological effect of aldosterone synthesis and secretion is mediated by either Gq/11 proteins or ßarrestin1 (ßarr1), both of which can couple to its type 1 receptors (AT1Rs), present in adrenocortical zona glomerulosa (AZG) cell membranes. In the present study, we examined the relative potencies of all the currently used in the clinic AT1R antagonist drugs (angiotensin receptor blockers, ARBs, or sartans) at preventing activation of these two signaling mediators (G proteins and ßarrs) at the AngII-bound AT1R and, consequently, at suppression of aldosterone in vitro. All ARBs were found to be potent inhibitors of G protein activation at the AT1R. However, candesartan and valsartan were the most potent at blocking AngII-induced ßarr activation at this receptor, among the tetrazolo-biphenyl-methyl derivatives, translating into excellent efficacies at aldosterone suppression in H295R cells. Conversely, irbesartan and losartan were largely G protein-selective inhibitors at the AT1R, with very low potency towards ßarr inhibition. As a result, they were very weak suppressors of ßarr1-dependent aldosterone production in H295R cells. These findings provide important pharmacological insights into the drug class of ARBs and medicinal chemistry insights for future drug development in the field of AngII antagonism.
Subject(s)
Adrenal Glands/metabolism , Aldosterone/biosynthesis , Angiotensin Receptor Antagonists/pharmacology , Arrestins/metabolism , Angiotensin II/pharmacology , Angiotensin Receptor Antagonists/chemistry , Animals , Benzimidazoles/pharmacology , Biphenyl Compounds , CHO Cells , Cricetinae , Cricetulus , GTP-Binding Proteins/metabolism , Humans , Phosphoproteins/metabolism , Rats , Receptor, Angiotensin, Type 1/metabolism , Tetrazoles/pharmacology , Up-Regulation/drug effects , Valine/analogs & derivatives , Valine/pharmacology , Valsartan , Zona Glomerulosa , beta-ArrestinsSubject(s)
Angiotensin II Type 1 Receptor Blockers/therapeutic use , Benzimidazoles/therapeutic use , Hyperaldosteronism/prevention & control , Myocardial Infarction/complications , Tetrazoles/therapeutic use , Valine/analogs & derivatives , Aldosterone/blood , Animals , Biphenyl Compounds , Rats , Valine/therapeutic use , ValsartanABSTRACT
ß-Arrestin (ßarr)-1 and ß-arrestin-2 (ßarrs) are universal G-protein-coupled receptor adapter proteins that negatively regulate cardiac ß-adrenergic receptor (ßAR) function via ßAR desensitization and downregulation. In addition, they mediate G-protein-independent ßAR signaling, which might be beneficial, for example, antiapoptotic, for the heart. However, the specific role(s) of each ßarr isoform in cardiac ßAR dysfunction, the molecular hallmark of chronic heart failure (HF), remains unknown. Furthermore, adrenal ßarr1 exacerbates HF by chronically enhancing adrenal production and hence circulating levels of aldosterone and catecholamines. Herein, we sought to delineate specific roles of ßarr1 in post-myocardial infarction (MI) HF by testing the effects of ßarr1 genetic deletion on normal and post-MI cardiac function and morphology. We studied ßarr1 knockout (ßarr1KO) mice alongside wild-type controls under normal conditions and after surgical MI. Normal (sham-operated) ßarr1KO mice display enhanced ßAR-dependent contractility and post-MI ßarr1KO mice enhanced overall cardiac function (and ßAR-dependent contractility) compared with wild type. Post-MI ßarr1KO mice also show increased survival and decreased cardiac infarct size, apoptosis, and adverse remodeling, as well as circulating catecholamines and aldosterone, compared with post-MI wild type. The underlying mechanisms, on one hand, improved cardiac ßAR signaling and function, as evidenced by increased ßAR density and procontractile signaling, via reduced cardiac ßAR desensitization because of cardiac ßarr1 absence, and, on the other hand, decreased production leading to lower circulating levels of catecholamines and aldosterone because of adrenal ßarr1 absence. Thus, ßarr1, via both cardiac and adrenal effects, is detrimental for cardiac structure and function and significantly exacerbates post-MI HF.