Protein expression profiles in murine ventricles modeling catecholaminergic polymorphic ventricular tachycardia: effects of genotype and sex

Abstract

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is associated with mutations in the cardiac ryanodine receptor (RyR2). These result in stress-induced ventricular arrhythmic episodes, with clinical symptoms and prognosis reported more severe in male than female patients. Murine homozygotic RyR2-P2328S (RyR2 S/S) hearts replicate the proarrhythmic CPVT phenotype of abnormal sarcoplasmic reticular Ca 2+ leak and disrupted Ca 2+ homeostasis. In addition, RyR2 S/S hearts show decreased myocardial action potential conduction velocities (CV), all features implicated in arrhythmic trigger and substrate. The present studies explored for independent and interacting effects of RyR2 S/S genotype and sex on expression levels of molecular determinants of Ca 2+ homeostasis (CASQ2, FKBP12, SERCA2a, NCX1, and Ca V 1.2) and CV (Na V 1.5, Connexin (Cx)-43, phosphorylated-Cx43, and TGF-β1) in mice. Expression levels of Ca 2+ homeostasis proteins were not altered, hence implicating abnormal RyR2 function alone in disrupted cytosolic Ca 2+ homeostasis. Furthermore, altered Na V 1.5, phosphorylated Cx43, and TGF-β1 expression were not implicated in the development of slowed CV. By contrast, decreased Cx43 expression correlated with slowed CV, in female, but not male, RyR2 S/S mice. The CV changes may reflect acute actions of the increased cytosolic Ca 2+ on Na V 1.5 and Cx43 function.

Cardiac ion channel expression in the equine model ‐ In‐silico prediction utilising RNA sequencing data from mixed tissue samples

“…For example, different brain region (Khaitovich et al, 2004 ) or different muscle fibres types (Rubenstein et al, 2020 ) can display different gene expression profile. This is especially the case in the heart where previous studies in other species have demonstrated differing ion channel expression not only between atria and ventricles but also within different regions of each chamber such as between the epicardium and myocardium (Bartos et al, 2015 ; Saadeh, Chadda, et al, 2020 ; Schram et al, 2002 ;). Hence, the method and site of sampling can, for those tissues, explain the differences between samples.…”

“…These include ryanodine receptor (RyR) responsible for Ca 2+ release from the sarcoplasmic reticulum (SR), SR Ca 2+ ‐binding calsequestrin (CASQ) which exerts important modulatory inhibitory or enhancing effects on RyR‐mediated Ca 2+ release at low or high SR luminal Ca 2+ concentrations, respectively (Chen et al, 2013 ; Györke & Terentyev, 2008 ; Handhle et al, 2016 ), and the cardiac SR Ca 2+ ‐ATPase (SERCA) which is key to terminating the cardiac cycle through diastolic reuptake of cytosolic Ca 2+ into the SR (Bers, 2002 ). Disruption in any of the Ca 2+ handling component will inevitably compromise cardiac function and has been associated with a wide range of conditions including proarrhythmic conditions such as catecholaminergic polymorphic ventricular tachycardia (CPVT) (Saadeh, Achercouk, et al, 2020 ). Of those Ca 2+ handling proteins, the RYR2, SERCA2, and CASQ2 are the most expressed isoforms in the human heart whereas our model predicted RYR1, SERCA1, and CASQ1 to be the most expressed isoforms in equine hearts.…”

Arrhythmic Outcomes in Catecholaminergic Polymorphic Ventricular Tachycardia

“…However, functional studies are needed to determine the precise mechanisms by which this structural change can lead to the generation of electrophysiological substrate. Previous animal studies have reported that the RyR2 mutations can be associated with not only disrupted calcium homeostasis but also reduced conduction velocity [59][60][61].…”

Clinical Characteristics, Genetic Findings and Arrhythmic Outcomes of Patients with Catecholaminergic Polymorphic Ventricular Tachycardia from China

“…However, functional studies are needed to determine the precise mechanisms by which this structural change can lead to the generation of an electrophysiological substrate. Previous animal studies have reported that the RyR2 mutations can be associated with not only disrupted calcium homeostasis but also reduced conduction velocity [55][56][57].…”