miR-92b-3p靶向肌细胞增强子2D抑制心肌细胞肥大

Targeting Myocyte-specific Enhancer Factor 2D Contributes to the Suppression of Cardiac Hypertrophic Growth by MiR-92b-3p in Cardiomyocytes

【目的】探讨微小RNAmicroRNA-92b-3p(mi R-92b-3p)对心肌细胞肥大的调控作用及其作用靶基因。【方法】建立血管紧张素Ⅱ(Ang-Ⅱ)诱导的C57BL/6小鼠心肌肥厚模型。通过尾静脉注射胆固醇修饰的mi R-92b-3p模拟物(agomi R-92b-3p)来增加小鼠心肌中mi R-92b-3p水平,分别设立3个实验组:agomi R-negative control(agomi R-NC)+saline组,agomi RNC+Ang-Ⅱ组,agomi R-92b-3p+Ang-Ⅱ组。用Ang-Ⅱ诱导乳小鼠心肌细胞建立心肌细胞肥大模型;双荧光素酶报告基因实验检测mi R-92b-3p与潜在靶基因MEF2D 3'端非翻译区(3'-UTR)的结合作用;蛋白印迹法检测MEF2D及肥厚相关蛋白的表达。【结果】(1)Ang-II诱导的小鼠肥厚心肌和肥大心肌细胞分别与对照组中心肌肥厚相关基因ANP、ACTA1和β-MHC水平比较,差异具有统计学意义(P<0.05);(2)双荧光素酶报告基因实验结果提示mi R-92b-3p与MEF2D 3′UTR具有相互结合作用;mi R-92b-3p可在转录后水平抑制MEF2D的表达;升高mi R-92b-3p或降低MEF2D水平能一致性地抑制Ang-II诱导的乳小鼠心肌细胞肥大表型。【结论】MEF2D是mi R-92b-3p的靶基因,并介导了mi R-92b-3p发挥抑制心肌细胞肥大的作用。

【Objective】To investigate the role and the potential target of mi R-92 b-3 p in angiotensin Ⅱ(Ang-Ⅱ)-induced mouse cardiac hypertrophy. 【Methods】 Ang-Ⅱ-induced cardiac hypertrophy models were established in adult C57 BL/6 mice.Agomi R-92 b-3 p,the cholesterol-modified mi R-92 b-3 p mimic,was delivered to increase the level of mi R-92 b-3 p in mouse myocardium via tail vein injection. In the present study,three groups of mice were used in the animal experiment as follows,the agomi Rnegative control(agomi R-NC)+saline group,the agomi R-NC+Ang-Ⅱ group and the agomi R-92 b-3 p+Ang-Ⅱ group. A cell model of cardiac hypertrophy was also established in Ang-Ⅱ-induced neonatal mouse cardiomyocytes in this study Luciferase activity was assayed after transfection using a luciferase reporter assay system. The expression of Myocyte-specific enhancer factor 2 D( MEF2 D)and hypertrophy-related genes atrial natriuretic peptide(ANP),cardiac muscle α-actin(ACTA1)and β-myosin heavy chain(MHC)at m RNA and protein levels in Ang-Ⅱ-induced hypertrophic myocardium and cardiomyocytes were detected by q RT-PCR and Western blot,respectively.【Results】The expression of ANP,ACTA1,β-MHC were markedly increased in Ang-Ⅱ-induced hypertrophic myocardium and cardiomyocytes. Dual luciferase reporter assay revealed that MEF2 D is a potential target gene of mi R-92 b-3 p. And mi R-92 b-3 p can reduce the expression of MEF2 D at the post-transcriptional level. Functionally,mi R-92 b-3 p mimic,consistent with MEF2 D si RNA,inhibited cell size increase and protein expression of ANP,ACTA1 and β-MHC in Ang-II-treated mouse cardiomyocytes.【Conclusions】MEF2 D is a novel target of mi R-92 b-3 p,a target gene of mi R-92 b-3,which mediates the effect of mi R-92 b-3 p on attenuating cardiomyocyte hypertrophy.