Let-7a Is an Antihypertrophic Regulator in the Heart via Targeting Calmodulin.
Let-7a Is an Antihypertrophic Regulator in the Heart via Targeting Calmodulin.
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Let-7a 是一种通过靶向钙调蛋白的心脏抗肥厚调节剂。
DOI：
10.7150/ijbs.16298
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发表时间：
2017
影响因子：
9.2
通讯作者：
Lu Y
中科院分区：
文献类型：
--
作者：
Zhou X;Sun F;Luo S;Zhao W;Yang T;Zhang G;Gao M;Lu R;Shu Y;Mu W;Zhuang Y;Ding F;Xu C;Lu Y
背景：microRNAs(MiRNAs)已成为多种心血管疾病的重要调节因子，包括心律失常、心肌肥大和纤维化以及心肌梗死。本研究旨在探讨miRNA let-7a在血管紧张素II(AngII)诱导的心肌肥厚中是否具有抗肥厚作用。方法：新生大鼠心肌细胞经血管紧张素转换酶抑制剂处理36h后，皮下注射血管紧张素转换酶抑制剂2周，建立小鼠心肌肥厚模型。采用免疫荧光细胞化学法测定细胞表面积，实时定量聚合酶链式反应检测心肌肥厚相关基因心钠素、脑钠素、β-MHC的表达，荧光素酶活性测定钙调素基因的结合部位，Western印迹法检测钙调素蛋白表达，超声心动图检测心肌肥厚参数。结果：在体内外血管紧张素转换酶诱导的心肌肥厚中，LET-7a的表达均降低。过表达let-7a可减轻血管紧张素Ⅱ诱导的细胞表面积增加，并抑制心钠素、脑钠素和β-MHcmRNA水平的升高。双荧光素酶报告基因分析表明，let-7a能与CaM-1基因的3‘端非编码区结合。Let-7a下调CaM蛋白的表达。在体内，let-7a对心肌肥大有抑制作用，包括下调小鼠心肌细胞横截面积，降低室间隔缺损和左心室收缩末期内径，抑制肥厚标志物基因心钠素、脑钠素、β-MHC的mRNA水平，下调CaM蛋白水平。结论：let-7a通过靶向CaM基因具有显著的抗肥大作用。这一发现为研究心肌肥厚的分子机制提供了新的视角。
Background: MicroRNAs (miRNAs) have been emerged as important regulator in a multiple of cardiovascular disease, including arrhythmia, cardiac hypertrophy and fibrosis, and myocardial infarction. The aim of this study was to investigate whether miRNA let-7a has antihypertrophic effects in angiotensin II (AngII)-induced cardiac hypertrophy. Methods: Neonatal rat ventricular myocytes (NRVMs) were exposed to AngII for 36 h as a cellular model of hypertrophy; subcutaneous injection of AngII for 2 weeks was used to establish a mouse model of cardiac hypertrophy in vivo study. Cell surface area (CSA) was measured by immunofluorescence cytochemistry; expression of hypertrophy-related genes ANP, BNP, β-MHC was detected by Real-time PCR; luciferase activity assay was performed to confirm the miRNA's binding site in the calmodulin (CaM) gene; CaM protein was detected by Western blot; the hypertrophy parameters were measured by echocardiographic assessment. Results: The expression of let-7a was decreased in AngII-induced cardiac hypertrophy in vitro and in vivo. Overexpression of let-7a attenuated AngII-induced increase of cell surface area and repressed the increased mRNA levels of ANP, BNP and β-MHC. Dual-luciferase reporter assay showed that let-7a could bind to the 3'UTR of CaM 1 gene. Let-7a downregulated the expression of CaM protein. In vivo, let-7a produced inhibitory effects on cardiac hypertrophy, including the downregulation of cross-sectional area of cardiomyocytes in mouse heart, the reduction of IVSD and LVPWD, the suppression of hypertrophy marker genes ANP, BNP, β-MHC mRNA level, and the downregulation of CaM protein level. Conclusions: let-7a possesses a prominent anti-hypertrophic property by targeting CaM genes. The findings provide new insight into molecular mechanism of cardiac hypertrophy.