Dual loss of regulator of G protein signaling 2 and 5 exacerbates ventricular myocyte arrhythmias and disrupts the fine-tuning of Gi/o signaling. (September 2022)

• Record Type: Journal Article
• Authors: Dahlen, Shelby A.; Bernadyn, Tyler F.; Dixon, Alethia J.; Sun, Bo; Xia, Jingsheng; Owens, Elizabeth A.; Osei-Owusu, Patrick
• Is Part Of: Journal of molecular and cellular cardiology. Volume 170(2022)
• Page Start: 34
• Page End: 46
• Publication Date: 2022-09
• Subjects: RGS proteins -- G protein signaling -- Cardiac excitation-contraction coupling -- Arrhythmia -- Cardiomyopathy -- cAMP -- Catecholamine; Cardiology -- Periodicals; Heart Diseases -- Periodicals; Molecular Biology -- Periodicals; Cardiologie -- Périodiques; Cardiology; Electronic journals; Periodicals; 616.12
• DOI: 10.1016/j.yjmcc.2022.05.009
• Languages: English
• ISSNs: 0022-2828

Abstract

Abstract: Aims: Cardiac contractility, essential to maintaining proper cardiac output and circulation, is regulated by G protein-coupled receptor (GPCR) signaling. Previously, the absence of regulator of G protein signaling (RGS) 2 and 5, separately, was shown to cause G protein dysregulation, contributing to modest blood pressure elevation and exaggerated cardiac hypertrophic response to pressure-overload. Whether RGS2 and 5 redundantly control G protein signaling to maintain cardiovascular homeostasis is unknown. Here we examined how the dual absence of RGS2 and 5 ( Rgs2/5 dbKO) affects blood pressure and cardiac structure and function. Methods and results: We found that Rgs2/5 dbKO mice showed left ventricular dilatation at baseline by echocardiography. Cardiac contractile response to dobutamine stress test was sex-dependently reduced in male Rgs2/5 dbKO relative to WT mice. When subjected to surgery-induced stress, male Rgs2/5 dbKO mice had 75% mortality within 72–96 h after surgery, accompanied by elevated baseline blood pressure and decreased cardiac contractile function. At the cellular level, cardiomyocytes (CM) from Rgs2/5 dbKO mice showed augmented Ca 2+ transients and increased incidence of arrhythmia without augmented contractile response to electrical field stimulation (EFS) and activation of β-adrenergic receptors (βAR) with isoproterenol. Dual loss of Rgs2 and 5 suppressed forskolin-induced cAMP production, which was restored by Gi/o inactivation with pertussis toxin that also reduced arrhythmogenesis during EFS or βAR stimulation. Cardiomyocyte NCX and PMCA mRNA expression was unaffected in Rgs2/5 dbKO male mice. However, there was an exaggerated elevation of EFS-induced cytoplasmic Ca 2+ in the presence of SERCA blockade with thapsigargin. Conclusions: We conclude that RGS2 and 5 promote normal ventricular rhythm by coordinating their regulatory activity towards Gi/o signaling and facilitating cardiomyocyte calcium handling. Graphical abstract: Unlabelled Image Highlights: Dual loss of Rgs2 and 5 causes left ventricular dilatation, arrhythmias, and sex-related death following surgery-induced stress. Myocytes null for Rgs2 & 5 are prone to βAR and EFS-induced arrhythmias with exagerated and sustained Ca 2+ elevation. Inhibition of Gi/o markedly reduces arrhythmia incidence in Rgs2/5 dbKO cardiomyocytes. RGS2 and 5 coordinate their G protein regulatory activity to finetune Gi/o signaling in ventricular myocytes.