Supplementary Material for: Cardiac-Specific Caveolin-3 Overexpression Prevents Post-Myocardial Infarction Ventricular Arrhythmias by Inhibiting Ryanodine Receptor-2 Hyperphosphorylation

<b><i>Introduction:</i></b> Ventricular arrhythmia is the most important risk factor for sudden cardiac death (SCD) after acute myocardial infarction (MI) worldwide. However, the molecular mechanisms underlying these arrhythmias are complex and not completely understood. <b><i>Objective:</i></b> Here, we evaluated whether caveolin-3 (Cav3), the structural protein of caveolae, plays an important role in the therapeutic strategy for ventricular arrhythmias. <b><i>Methods:</i></b> A model of cardiac-specific overexpression of Cav3 was established to evaluate the incidence of ventricular arrhythmias after MI in mice. Ca²⁺ imaging was employed to detect the propensity of adult murine cardiomyocytes to generate arrhythmias, and immunoprecipitation and immunofluorescence were used to determine the relationship of proteins. Additionally, qRT-PCR and western blotting were used to detect the mRNA and protein expression. <b><i>Results:</i></b> We found that cardiac-specific overexpression of Cav3 delivered by a recombinant adeno-associated viral vector reduced the incidence of ventricular arrhythmias and SCD after MI in mice. Ca²⁺ imaging and western blotting revealed that overexpression of Cav3 reduced diastolic spontaneous Ca²⁺ waves by inhibiting the hyperphosphorylation of ryanodine receptor-2 (RyR2) at Ser2814, rather than at Ser2808, compared to in rAAV-red fluorescent protein control mice. Furthermore, we demonstrated that Cav3-regulated RYR2 hyperphosphorylation relied on plakophilin-2 in hypoxia-stimulated cultured cardiomyocytes by western blotting, immunoprecipitation, and immunofluorescence in vitro. <b><i>Conclusions:</i></b> Our results suggested a novel role for Cav3 in the prevention of ventricular arrhythmias, thereby identifying a new target for preventing SCD after MI.