AIM:To investigate whether KCNE 2 participates in the development of pathological hypertrophy .METHODS:Bidirectional ma-nipulations of KCNE2 expression were performed by adenoviral overexpression of KCNE 2 or knockdown of KCNE2 with RNA interfer-ence in PE-induced neonatal rat ventricular myocytes .Then overexpression of KCNE 2 in mouse model of left ventricular hypertrophy in-duced by transverse aortic constriction (TAC) by ultrasound microbubble-mediated gene transfer were used to detect the therapeutic function of KCNE2 in the development of hypertrophy .RESULTS:KCNE2 expression was significantly decreased in PE-induced hy-pertrophic cardiomyocytes and in hypertrophic hearts produced by TAC .Knockdown of KCNE2 in cardiomyocytes reproduced hypertro-phy, whereas overexpression of KCNE2 attenuated PE-induced cardiomyocyte hypertrophy .Knockdown of KCNE2 increased calcineurin activity and nuclear NFAT protein level , and pretreatment with nifedipine or FK 506 attenuated decreased KCNE 2-induced cardiomyo-cyte hypertrophy .Overexpression of KCNE 2 in heart by ultrasound microbubble-mediated gene transfer suppressed the development of hypertrophy and activation of calcineurin-NFAT and MAPK pathways in TAC mice .CONCLUSION:These findings demonstrate that cardiac KCNE2 expression is decreased and contributes to the development of hypertrophy via activation of calcineurin -NFAT and
MAPK pathways .

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-CLUSION:These findings establish MG53 as a novel regulator of Ito,f and its central role in arrhythmogenesis in hypertrophy .

AIM:To investigate the effect of miR-214 on cardiomyocyte hypertrophy and the expression of the potential target genes . METHODS:A cell model of hypertrophy was established based on angiotensin-Ⅱ( Ang-Ⅱ)-induced neonatal mouse ventricular car-diomyocytes (NMVCs).Dual luciferase reporter assay was performed to verify the interaction between miR-214 and the 3’ UTR of MEF2C.The expression of MEF2C and hypertrophy-related genes at mRNA and protein levels was determined by RT-qPCR and Wes-tern blotting, respectively.RESULTS:The expression of ANP, ACTA1,β-MHC and miR-214 was markedly increased in Ang-Ⅱ-in-duced hypertrophic cardiomyocytes .Dual luciferase reporter assay revealed that miR-214 interacted with the 3’ UTR of MEF2C, and miR-214 was verified to inhibit MEF2C expression at the transcriptional level .The protein expression of MEF2C was markedly in-creased in the hypertrophic cardiomyocytes .Moreover, miR-214 mimic, in parallel to MEF2C siRNA, inhibited the expression of hy-pertrophy-related genes in Ang-Ⅱ-induced NMVCs.CONCLUSION:MEF2C is a target gene of miR-214, which mediates the effect of miR-214 on attenuating cardiomyocyte hypertrophy .

AIM:MicroRNAs ( miRNAs) were recognized to play significant roles in cardiac hypertrophy .But, it remains unknown whether cyclin/Rb pathway is modulated by miRNAs during cardiac hypertrophy .This study investigates the potential roles of microRNA-1 (miR-1) and microRNA-16 (miR-16) in modulating cyclin/Rb pathway during cardiomyocyte hypertrophy .METHODS:An animal model of hypertrophy was established in a rat with abdominal aortic constriction (AAC).In addition, a cell model of hypertrophy was also achieved based on PE-promoted neonatal rat ventricular cardiomyocyte .RESULTS:miR-1 and-16 expression were markedly de-creased in hypertrophic myocardium and hypertrophic cardiomyocytes in rats .Overexpression of miR-1 and -16 suppressed rat cardiac hypertrophy and hypertrophic phenotype of cultured cardiomyocytes .Expression of cyclins D1, D2 and E1, CDK6 and phosphorylated pRb was increased in hypertrophic myocardium and hypertrophic cardiomyocytes , but could be reversed by enforced expression of miR-1 and -16.CDK6 was validated to be modulated post-transcriptionally by miR-1, and cyclins D1, D2 and E1 were further validated to be modulated post-transcriptionally by miR-16.CONCLUSION: Attenuations of miR-1 and -16 provoke cardiomyocyte hypertrophy via derepressing the cyclins D1, D2, E1 and CDK6, and activating cyclin/Rb pathway.