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本研究旨在探索钙网蛋白(CRT)在压力超负荷心肌肥厚大鼠模型和体外诱导的肥大心肌细胞中的表达变化及其可能的机制。通过腹主动脉缩窄术(TAC)构建压力超负荷的心肌肥厚大鼠模型,用实时荧光定量聚合酶链式反应(RT-qPCR)及Western blot检测CRT、肥大标志基因心房钠尿肽(ANP)、脑钠肽(BNP)及内质网应激(ERS)标志物葡萄糖调节蛋白78(GRP78)、活化转录因子6(ATF6)、C/EBP同源蛋白(CHOP)的表达变化。同时,应用ERS抑制剂阿托伐他汀(ATO)以及CRT小干扰核糖核酸(CRT-siRNA)分别抑制ERS和CRT的表达,来观察CRT在心肌肥厚中的作用。结果表明,SD大鼠行TAC术4周后即发生心肌肥厚,心肌组织中CRT、肥大标志基因及ERS标志物表达水平明显增加。给予TAC大鼠ATO口服干预4周,大鼠心脏结构及功能明显改善,心肌肥厚程度减轻,CRT及ERS相关指标表达受到抑制。而体外用去甲肾上腺素(NE)、血管紧张素Ⅱ(AngⅡ)或异丙肾上腺素(ISO)处理乳鼠原代心肌细胞(NCMs)后,均能诱导心肌细胞发生肥大,同时促发ERS,CRT表达亦增加。心肌细胞肥大时,沉默NCMs中CRT基因后,其肥大程度明显缓解,提示CRT可能是治疗心肌肥厚的潜在靶点。
This study aimed to explore the expression of calreticulin (CRT) in hypertrophic cardiomyocytes of hypertensive rats and hypertrophic cardiomyocytes induced in vitro and its possible mechanism. The rat model of hypertensive cardiac hypertrophy was established by abdominal aortic constriction (TAC). The levels of CRT, mRNA of atrial natriuretic peptide (ANP), a marker of hypertrophy, were detected by real-time quantitative polymerase chain reaction (RT-qPCR) ), Brain natriuretic peptide (BNP) and endoplasmic reticulum stress (ERS) markers such as GRP78, ATF6 and CHOP. At the same time, ERS inhibitor atorvastatin (ATO) and CRT small interfering RNA (CRT-siRNA) were used to inhibit the expression of ERS and CRT to observe the role of CRT in cardiac hypertrophy. The results showed that cardiac hypertrophy occurred in SD rats after TAC for 4 weeks, and the expression of CRT, hypertrophy markers and ERS markers in myocardium were significantly increased. After oral administration of ATO to TAC rats for 4 weeks, the cardiac structure and function of rats were significantly improved, the degree of myocardial hypertrophy was alleviated, and the expression of CRT and ERS was inhibited. In vitro treatment of primary neonatal cardiomyocytes (NCMs) with norepinephrine (NE), angiotensin II (Ang II) or isoprenaline (ISO) induced hypertrophy of cardiomyocytes and elicited ERS , CRT expression also increased. Hypertrophic cardiomyocytes, when silenced NCMs CRT gene, its hypertrophy significantly eased, suggesting that CRT may be a potential target for the treatment of cardiac hypertrophy.