MG53 regulation of KChIP2 and the fast transient outward K+current (Ito,f) and its central role in arrhythmogenesis in hypertrophic heart / 中国病理生理杂志

ABSTRACT

AIM:To investigate the regulation mechanism for insufficient KChIP 2 expression induces Ito,f downregulation and arrhythmogene-sis in cardiac hypertrophy .METHODS:Bidirectional manipulations of MG 53 expression were performed by adenoviral overexpression of MG53 or knockdown of MG53 with RNA interference in neonatal rat ventricular myocytes with or without PE stimulation .Ito,f was re-corded with patch clamp in whole-cell mode 48 h after adenoviral transfection .Then the WT or MG53 knockout ( MG53 -/-) mouse model of left ventricular hypertrophy induced by transverse aortic constriction ( TAC) were used to detect the susceptibility to ventricu-lar arrhythmia.RESULTS: Here, we show muscle-specific MG53 regulates KChIP2 expression and Ito,f densities, where they are downregulated in hearts from MG53 knockout mice and MG53 knockdown rat cardiomyocytes , but upregulated in MG53 overexpressed cells.MG53 expression is decreased in phenylephrine ( PE)-induced cardiomyocyte hypertrophy and restoration of MG 53 rescues PE-induced downregulation of KChIP2 and Ito,f.Furthermore, MG53 is decreased in a mouse model of hypertrophy induced by transverse aortic constriction and ablation of MG 53 increases the susceptibility to ventricular arrhythmia by exaggerating Ito,f remodeling.CON-CLUSIONThese findings establish MG53 as a novel regulator of Ito,f and its central role in arrhythmogenesis in hypertrophy .