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目的通过对比观察不同周龄自发性高血压大鼠(SHR)和正常血压对照大鼠(WKY)胸主动脉和肠系膜动脉中血管紧张素Ⅱ1a型受体(AT1aR)的mRNA和蛋白质表达及其甲基化水平的差异,探讨DNA甲基化与AT1aR表达及血压状态的内在联系。方法以同龄WKY大鼠为正常对照,分别从转录和翻译水平检测处于高血压前期(4周龄)、高血压发展期(10周龄)和高血压稳定形成期(20周龄)SHR胸主动脉和肠系膜动脉内AT1aR的表达变化,同时应用重亚硫酸盐修饰测序法评估AT1aR基因启动子区的甲基化状况。结果 SHR和WKY大鼠胸主动脉和肠系膜动脉内AT1aR的mRNA和蛋白质表达水平均随周龄增长而递增;自10周龄起,SHR胸主动脉和肠系膜动脉内AT1aR的mRNA和蛋白质表达水平高于同周龄的WKY大鼠,20周龄时差异有统计学意义(mRNA:胸主动脉为1.607±0.084比1.227±0.079,肠系膜动脉为1.713±0.103比1.327±0.066;蛋白:胸主动脉为1.594±0.071比1.237±0.064,肠系膜动脉为2.103±0.115比1.300±0.089;均P<0.01);SHR胸主动脉和肠系膜动脉内AT1aR基因启动子区两个CpG岛随着周龄的增长和血压的升高均发生去甲基化,自10周龄起SHR AT1aR基因启动子区甲基化水平已经开始低于同周龄的WKY大鼠,20周龄时差异有统计学意义(胸主动脉总甲基化率:1.4%比10.9%;肠系膜动脉总甲基化率:0.3%比8.0%;均P<0.01)。结论 SHR动脉血管中AT1aR基因启动子区随着年龄的增加去甲基化,可能在影响AT1aR的表达和原发性高血压的发病机制中起到一定作用。
Objective To compare the mRNA and protein expression of angiotensin Ⅱ type 1 receptor (AT1aR) in thoracic and mesenteric artery of spontaneously hypertensive rats (SHR) and normal control rats (WKY) The relationship between DNA methylation and AT1aR expression and blood pressure status was explored. Methods WKY rats of the same age were used as normal controls. The levels of SHR were detected in the prehypertensive (4 weeks), hypertensive (10 weeks) and stable (20 weeks) SHR stages at transcriptional and translational levels Arterial and mesenteric arteries AT1aR expression changes, and application of bisulfite modified sequencing method to assess AT1aR gene promoter methylation status. Results The mRNA and protein expression of AT1aR in the thoracic and mesenteric arteries of SHR and WKY rats both increased with the increase of age. From the age of 10 weeks, the mRNA and protein expressions of AT1aR in the thoracic aorta and mesenteric artery of SHR were high There was a significant difference in WKY rats at the age of 20 weeks (mRNA: 1.607 ± 0.084 vs 1.227 ± 0.079 in thoracic aorta, 1.713 ± 0.103 vs 1.327 ± 0.066 in mesenteric artery; 1.594 ± 0.071 vs 1.237 ± 0.064, and mesenteric artery was 2.103 ± 0.115 vs 1.300 ± 0.089, all P <0.01). The two CpG islands of AT1aR gene promoter in the thoracic and mesenteric arteries of SHR increased with age and blood pressure , The methylation of SHR AT1aR gene promoter region began to be lower than WKY rats of the same age since the age of 10 weeks, and the difference was statistically significant at the age of 20 weeks (thoracic aorta Total methylation rate: 1.4% vs 10.9%; Mesenteric artery total methylation rate: 0.3% vs 8.0%; all P <0.01). Conclusion The demethylation of AT1aR gene promoter region in SHR arteries may play an important role in affecting the expression of AT1aR and the pathogenesis of essential hypertension.