微小RNA-199a-5p调控大鼠心肌细胞肥大的研究*

 目的：探讨微小RNA-199a-5p（miR-199a-5p）在心肌肥大模型中的表达及对大鼠心肌细胞肥大的调控作用。方法：用腹主动脉缩窄术（TAAC）构建心肌肥大大鼠模型，体外培养新生Sprague-Dawley大鼠心肌细胞，用血管紧张素II(Ang II)诱导心肌细胞肥大，荧光定量PCR (qRT-PCR)检测动物血浆和心肌细胞miR-199a-5p含量；合成大鼠miR-199a-5p的拟似物（mimic）和抑制剂（inhibitor），用脂质体转染mimic和inhibitor进入心肌细胞，用qRT-PCR检测肥大基因心房钠尿因子和β-肌球蛋白重链mRNA的表达变化；用氚标亮氨酸掺入量检测细胞蛋白合成速率变化；用细胞荧光染色法检测细胞表面积变化。结果：TAAC 术后28 d，大鼠血浆miR-199a-5p的含量较对照组显著增加 (P<0.05)，在Ang II诱导肥大的心肌细胞中，miR-199a-5p的表达量也较对照组显著增加。在心肌细胞中过表达miR-199a-5p，能使细胞肥大基因表达增加,蛋白合成速率加快，细胞表面积增大，而使用inhibitor阻遏miR-199a-5p的作用后，能抑制Ang II诱导的肥大基因表达、细胞蛋白合成速率和细胞表面积的变化。结论:心肌肥大动物和细胞模型中miR-199a-5p的表达发生上调。过表达miR-199a-5p能促进体外培养的心肌细胞肥大，而阻遏miR-199a-5p的作用能抑制Ang II诱导的心肌细胞肥大。

Regulatory effect of miR-199a-5p on cardiomyocyte hypertrophy in rat

AIM：To investigate the expression of miR-199a-5p in rat cardiomyocyte hypertrophy models. METHODS：The in vivo cardiomyocyte hypertrophy model was established by transverse abdominal aortic constriction (TAAC) and the in vitro model was induced by angiotensin II. The content of miR-199a-5p was detected by qRT-PCR in the plasma of the TAAC rats and in the cardiomyocytes (CM) of the newborn rats. The CM was isolated and transfected with miR-199a-5p mimic or inhibitor at concentration of 100 nmol/L by Lipofectamine RNAiMAX. The mRNA levels of atrial natriuretic factor (ANF) and  β-myosin heavy chain (β-MHC) were detected by qRT-PCR. Tritium-labeled leucine incorporation was employed to determine the protein synthesis rate in the CM. The method of cyto-fluorescent staining was applied to measure the changes of the CM surface area. RESULTS：Compared with control group, the content of miR-199a-5p significantly increased in the TAAC rats and in the CM induced by angiotensin II. In addition, over-expression of miR-199a-5p in the CM up-regulated the mRNA expression of ANF and β-MHC, accelerated the protein synthesis rate and enlarged the CM surface area. In the CM transfected with miR-199a-5p inhibitor following induced by angiotensin II, the hypertrophy effect receded inversely (P<0.05). CONCLUSION:Over-expression of miR-199a-5p may promote cardiomyocyte hypertrophy, and repression of miR-199a-5p may inhibit cardiomyocyte hypertrophy in the CM.