肌原纤维调节因子-1在心肌肥大中的作用研究

目的：研究肌原纤维调节因子-1(MR1)在心肌肥大中的变化及其作用。 方法： 选取rMR1 mRNA的3个Stem-loop结构作为靶点，构建RNA干扰载体，对乳鼠心肌细胞进行瞬时转染，通过定量RT-PCR，选定第1靶点进行RNA干扰以封闭MR1基因；采用心肌细胞［3H］-亮氨酸掺入、形态学检测、蛋白质提取、Western blotting技术，检测蛋白合成速率、细胞表面积、rMR1蛋白表达等指标，观察MR1基因沉默对于血管紧张素Ⅱ (angiotensin Ⅱ, AngⅡ)诱导的乳鼠心肌细胞肥大的影响。 结果： AngⅡ组［3H］-亮氨酸掺入较对照组增加24.1%(P<0.01)，其细胞表面积较对照组高65.8%(P<0.01)，rMR-1蛋白表达水平升高；AngⅡ的上述作用可被卡托普利完全消除；MR1基因封闭后，由AngⅡ诱导的［3H］-亮氨酸掺入降低30.2%(P<0.01)，细胞表面积较AngⅡ组降低31.1%(P<0.01)，rMR-1蛋白表达较对照组减少。 结论： AngⅡ诱导的心肌细胞肥大与rMR-1表达上调有关。MR-1可能通过促进心肌收缩蛋白的合成参与心肌肥大的发生。

Effects of myofibrillogenesis regulator on myocardial hypertrophy

AIM: To investigate the effects of myofibrillogenesis regulator-1 (MR1) on myocardial hypertrophy. METHODS: Three stem-loop structures of rMR1 mRNA were selected as targets to establish RNA interference carriers. After transient transfection with plasmids, cultured cardiomyocytes of neonatal were used to perform RT-PCR for choosing the first target to carry out RNA interference blocking MR1 gene. In order to observe the effect of MR1 gene silence on myocardial hypertrophy induced by angiotensin Ⅱ (AngⅡ), the radiation intensity of tritium-leucine (［3H］-Leu) was used to label the cardiomyocytes. Morphological observation, protein extraction and Western blotting were also used to investigate protein synthesis rate, cell surface area and expression of rMR1. RESULTS: The radiation intensity of tritium-Leucine in AngⅡ group increased 21.4% (P<0.01), the cell surface area increased 65.8% (P<0.01) and the expression of rMR1 was up-regulated. Captopril, an inhibitor of angiotensin converting enzyme, abolished the hypertrophy effect and expression of rMR1 induced by AngⅡ. After MR1 gene blocking, the radiation intensity and cell area decreased 30.2% and 31.1% (P<0.01), respectively, compared to AngⅡ group. The expression of rMR1 was depressed. CONCLUSIONS: AngⅡ induces myocardial hypertrophy and upregulates expression of rMR1. Preconditioning with captopril eliminates the effect of AngⅡ, indicating that the increased expression of rMR1 is correlated with myocardial hypertrophy induced by AngⅡ. Blocking of MR1 gene abolishes the effect of AngⅡ and depresseses the expression of rMR1, the effect is similar to ACEI, indicating that MR1 takes part in the procession of hypertrophy through promoting the synthesis of contractive protein in cardiomyocytes.