ECE-1基因去甲基化在腹主动脉缩窄术后左室肥厚大鼠中的作用及机制研究

目的：探讨内皮素转换酶1（ECE-1）基因去甲基化在腹主动脉缩窄术（AAC）左室肥厚大鼠中的作用，及对磷脂酰肌醇3激酶/蛋白激酶B（PI3K/PKB）信号通路的影响。方法：雄性SD大鼠30只，随机分为3组：空白组、模型组和假手术组，每组10只。模型组采用腹主动脉缩窄术建立压力超负荷心肌肥厚模型，假手术组分离腹主动脉但不结扎。6周后，超声心动图检测左室舒张末内径（LVED）、左室舒张末后壁厚度（LVPWT）、射血分数（EF）、短轴收缩率（FS），称重计算心脏质量指数（HWI），HE染色观察心肌细胞面积（AMC），甲基化特异性PCR检测心肌ECE-1基因去甲基化水平的变化，实时荧光定量PCR检测心房利钠肽（ANP）、ECE-1 mRNA表达变化，ELISA检测血浆内皮素1（ET-1）水平，Western blot检测p-PI3K、PI3K、p-PKB、PKB蛋白表达变化。结果：假手术组大鼠LVPWT、LVED、EF、FS、HWI、AMC、ANP和ECE-1 mRNA、ECE-1基因去甲基化水平以及p-PI3K、p-PKB蛋白水平与对照组无明显差异。与假手术组相比，模型组大鼠LVPWT、HWI、AMC增大，心肌组织ECE-1基因去甲基化水平升高，ECE-1和ANP mRNA表达上调，血浆ET-1水平上升（P < 0.01），LVED、EF、FS减小，心肌组织p-PI3K、p-PKB蛋白表达下调（P < 0.01或P < 0.05）。结论：ECE-1基因去甲基化可能参与了压力超负荷大鼠心肌肥厚的形成过程，该过程可能与PI3K/PKB信号通路的抑制有关。

Demethylation of ECE-1 in left ventricular hypertrophy among rats after abdominal aortic constriction

OBJECTIVE: To investigate the effect of demethylation of endothelin converting enzyme 1 (ECE-1) gene on left ventricular hypertrophy in rats undergoing abdominal aortic constriction (AAC) and its effect on the PI3K/PKB signaling pathway. METHODS: 30 male SD rats were randomly divided into three groups:control,model and sham groups,with 10 rats in each group. Pressure overload myocardial hypertrophy model was established by AAC in the model group,abdominal aorta was isolated in the sham group but not ligated,and conventional operation was not performed in the control group. Left ventricular end-diastolic diameter (LVED),left ventricular posterior wall thickness (LVPWT),ejection fractions (EF),and fractional shortening (FS) were measured using echocardiography. Heart weight indices (HWI) were calculated after weighing. The areas of myocardial cells (AMC) were measured using hematoxylin-eosin staining. Demethylation levels of ECE-1 genes were detected using methylation-specific PCR. Expressions of atrial natriuretic peptide (ANP) and ECE-1 were detected using Real-time quantitative PCR. Plasma endothelin 1 (ET-1) levels were detected using enzyme-linked immunosorbent assay. Protein expressions of p-PI3K,PI3K,p-PKB and PKB were detected using Western blot. RESULTS: Compared with the control group,there were no statistically significant differences in the indicators of the sham group. Compared with the sham group,LVPWT,HWI,AMC,the demethylation level of ECE-1 gene in ventricular myocardium,plasma ET-1 level,ECE-1 and ANP mRNA in model group were increased (P < 0.01). LVED,EF,FS and the protein expression of p-PI3K and p-PKB in myocardium were decreased (P < 0.01 or P < 0.05). CONCLUSION: ECE-1 gene demethylation is involved in the formation of pressure overload cardiac hypertrophy,which may be related to the inhibition of PI3K/PKB signaling pathway.