线粒体翻译延伸因子Ts对心肌肥大的作用及机制

ROLE OF MITOCHONDRIAL TRANSLATION ELONGATION FACTOR TS IN CARDIAC HYPERTROPHY AND UNDERLYING MECHANISM

目的探究线粒体翻译延伸因子Ts(EF-Ts)通过影响线粒体损伤调控病理性心肌细胞肥大的分子机制。方法使用血管紧张素Ⅱ(AngⅡ)制备小鼠心肌肥大的细胞模型与动物模型,采用蛋白免疫印迹(WB)方法检测心肌肥大时EF-Ts的蛋白表达。用EF-Ts干扰慢病毒干扰小鼠原代心肌细胞中EF-Ts的表达,同时用AngⅡ处理,借助四甲基罗丹明甲酯(TMRM)与钙黄绿素乙酰氧基甲酯(Calcein AM)染色,应用激光共聚焦显微镜观察心肌细胞线粒体膜电位和线粒体通透性转换孔(MPTP)水平,并采用WB法检测心肌肥大标志物心房钠尿因子(ANF)和钠尿肽B(NPPB)的变化情况。结果心肌肥大的细胞模型和动物模型中EF-Ts蛋白表达量均明显降低(t=2.95、14.93,P<0.05)。与对照组相比,AngⅡ诱导的心肌肥大细胞模型中TMRM和Calcein AM染色荧光强度均明显减弱,在心肌肥大细胞模型中敲低EF-Ts后TMRM和Calcein AM染色荧光强度进一步减弱(F=4.22~22.88,P<0.05),而心肌肥大标志物ANF、NPPB蛋白表达量进一步上升(F=6.52、20.96,P<0.05)。结论EF-Ts缺失可能引起线粒体功能损伤而导致心肌肥大,因此EF-Ts有可能成为干预心肌肥大的重要靶标。

Objective To explore the molecular mechanism of the mitochondrial translation elongation factor EF-Ts re-gulating pathological cardiomyocyte hypertrophy through affecting mitochondrial injury.Methods AngiotensinⅡ(AngⅡ)was used to prepare cell and animal models of cardiac hypertrophy in mice.Western blot was used to measure the expression of EF-Ts protein in cardiac hypertrophy.EF-Ts-interfering lentivirus was used to interfere the expression of EF-Ts in mouse primary cardiomyocytes.After treatment with AngⅡand staining with tetramethylrhodamine methyl ester(TMRM)and calcein acetoxymethyl ester(Calcein AM),a laser confocal microscope was used to observe the mitochondrial membrane potential and mitochondrial permeability transition pore level of cardiomyocytes.Western blot was used to determine the changes of atrial natriuretic factor(ANF)and natriuretic peptide B(NPPB),which were the markers of cardiac hypertrophy.Results The expression of EF-Ts protein in both the cell model and animal model of cardiac hypertrophy was decreased significantly(t=2.95,14.93;P<0.05).Compared with those in the control group,the fluorescence intensities of TMRM and Calcein AM were significantly decreased in AngⅡ-induced cell model of cardiac hypertrophy,and were further significantly reduced after knocking down EF-Ts in the model of cardiac hypertrophy(F=4.22-22.88,P<0.05),while the expression of ANF and NPPB proteins was further significantly increased(F=6.52,20.96;P<0.05).Conclusion EF-Ts deletion may cause mitochondrial dysfunction,and thereby lead to cardiac hypertrophy.Therefore,EF-Ts may be a key target for the intervention of cardiac hypertrophy.