Cardiac-targeted PIASy Gene Silencing Mediates deSUMOylation of Caveolin-3 and Prevents Ischemia/reperfusion-induced Nav1.5 Down-regulation and Ventricular Arrhythmias

Abstract Background: Abnormal myocardial expression and function of Na v 1.5 causes lethal ventricular arrhythmias during myocardial ischemia-reperfusion (I/R). PIASy mediated Caveolin-3 (Cav-3) SUMO modification affects Cav-3 binding to ligand Na v 1.5. PIASy activity is increased after myocardial I/R, whether or not this may be attributable to plasma membrane Na v 1.5 downregulation and ventricular arrhythmias remains unclear. Methods: Using recombinant adeno-associated virus subtype 9 (AAV9), rat cardiac PIASy was silenced by intraventricular injection of PIASy shRNA. Two weeks later, the hearts were subjected to I/R, and electrocardiography was performed to assess malignant arrhythmias. Tissues from peri-infarct areas of the left ventricle were collected for molecular biological measurement. Results: We found that PIASy was upregulated by I/R, with increased SUMO2/3 modification of Cav-3, reduced membrane Na v 1.5 density, and increased ventricular arrhythmia frequency. These effects were significantly reversed by PIASy silencing. In addition, PIASy silencing enhanced Cav-3 binding to Na v 1.5 and prevented I/R-induced Na v 1.5 re-localization. Using in vitro models of HEK293T cells and isolated adult rat cardiomyocytes exposed to hypoxia/reoxygenation (H/R), this reserch further confirmed that PIASy promoted Cav-3 modification by SUMO2/3 and Na v 1.5/Cav-3 dissociation after H/R. Mutation of the SUMO Consensus Sites Lysine in Cav-3 (K38R or K144R) alters the membrane expression levels of Na v 1.5 and Cav-3 before and after H/R in HEK293T cells. Conclusions: I/R-induced cardiac PIASy activation contributes to Cav-3 SUMOylation by SUMO2/3 and dysregulated Na v 1.5- related ventricular arrhythmias. Cardiac-targeted PIASy gene silencing mediates deSUMOylation of Cav-3 and prevents I/R-induced Na v 1.5 down-regulation and ventricular arrhythmias in rats, identifying PIASy as a potential therapeutic target for relevant life-threatening arrhythmias in patients with ischemic heart diseases.