Effect of miR-195-5p on myocardial fibrosis in atrial fibrillation rats by targeting SMAD homolog 7 to regulate TGF-β1
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目的 探究微小 RNA-195-5p(microRNA-195-5p,miR-195-5p)对心房颤动(atrial fibrillation,AF)大鼠心肌纤维化的影响与机制.方法 选择雄性SD大鼠72只,随机分为对照组、AF组、阴性对照组、miR-195-5p组(miR-195-5p 抑制剂)、9 型重组腺相关病毒(recombinant adeno-associated virus serotype 9,rAAV9)组(miR-195-5p抑制剂+rAAV9-阴性对照)、联合组[miR-195-5p抑制剂+rAAV9-小干扰RNA-SMAD同源物(SMAD homolog,Smad)7,每组12只.除对照组外,其他组大鼠构建AF模型.给予对应干预措施后,进行心电图测试,记录AF发生率和持续时间;HE染色检测心肌组织病理变化;Masson染色检测心肌组织纤维化程度;实时荧光定量聚合酶链反应检测心肌组织 miR-195-5p、Smad7 mRNA表达;Western blot检测心肌组织转化生长因子β1(transforming growth factor-β1,TGF-β1)、Smad2、磷酸化 Smad2、Smad3、磷酸化 Smad3、Smad7、Ⅰ 型胶原蛋白(Collagen-Ⅰ)、Ⅲ型胶原蛋白(Collagen-Ⅲ)表达;双荧光素酶实验验证miR-195-5p对Smad7的调控作用.结果 与对照组比较,AF 组 AF 发生率(75.0％vs 0)和持续时间[(27.02±2.65)s vs 0 s]、胶原容积分数[(14.47±0.89)％vs(2.12±0.35)％]、心肌组织 miR-195-5p(3.27±0.21 vs 1.00±0.10)、TGF-β1(0.76±0.08 vs 0.23±0.04)、Collagen-Ⅰ(0.58±0.07 vs 0.20±0.04)、Collagen-Ⅲ(0.46±0.05 vs 0.11±0.02)、磷酸化 Smad2/Smad2(0.92±0.10 vs 0.37±0.05)、磷酸化 Smad3/Smad3(0.65±0.06 vs 0.14±0.03)表达明显升高,Smad7 mRNA(0.32±0.06 vs 1.02±0.09)和Smad7(0.19±0.03 vs 0.58±0.07)表达明显降低,差异有统计学意义(P＜0.05);与AF组和阴性对照组比较,miR-195-5p组AF发生率和持续时间、胶原容积分数、心肌组织miR-195-5p、TGF-β1、Collagen-Ⅰ、Collagen-Ⅲ、磷酸化Smad2/Smad2和磷酸化Smad3/Smad3表达明显降低,Smad7 mRNA和蛋白表达明显升高,差异有统计学意义(P＜0.05);与miR-195-5p组和rAAV9组比较,联合组AF发生率和持续时间、胶原容积分数、心肌组织TGF-β1、Collagen-Ⅰ、Collagen-Ⅲ、磷酸化 Smad2/Smad2 和磷酸化 Smad3/Smad3 表达明显升高,Smad7 mRNA 和 Smad7表达明显降低,差异有统计学意义(P＜0.05).结论 下调miR-195-5p可能靶向Smad7抑制TGF-β1信号传导,从而减轻AF心肌纤维化.
Objective To investigate the effect and mechanism of miR-195-5p on myocardial fibro-sis in rats with atrial fibrillation(AF).Methods A total of 72 male SD rats were randomly divid-ed into control group,AF group,negative control group,miR-195-5p inhibitor group,recombinant adeno-associated virus serotype 9(rAAV9)group(miR-195-5p inhibitor+rAAV9-negative con-trol),and combination group[miR-195-5p inhibitor+rAAV9-siRNA-SMAD homolog 7(Smad)],with 12 rats in each group.Except for the control group,the rats in the other groups were inflicted to construct AF model.After receiving corresponding intervention measures,elec-trocardiography was conducted to record the incidence and the duration of AF.HE staining and Masson staining were used to observe the pathological changes and fibrosis in the myocardial tis-sues,respectively.qRT-PCR was applied to detect the mRNA levels of miR-195-5p and Smad7,and Western blotting was performed to detect the expression of TGF-β1,Smad2,p-Smad2,Smad3,p-Smad3,Smad7,Collagen-Ⅰ and Collagen-Ⅲ in the myocardial tissues.Dual luciferase assay was used to verify the regulatory effect of miR-195-5p on Smad7.Results Compared with the control group,the AF group had significantly higher AF incidence(75.0％vs 0)and longer duration(27.02±2.65 s vs 0 s),larger collagen volume fraction(CVF)[(14.47±0.89)％vs(2.12±0.35)％],and increased expression levels of miR-195-5p(3.27±0.21 vs 1.00±0.10),TGF-β1(0.76±0.08 vs 0.23±0.04),Collagen-Ⅰ(0.58±0.07 vs 0.20±0.04),Collagen-Ⅲ(0.46±0.05 vs 0.11±0.02),p-Smad2/Smad2(0.92±0.10 vs 0.37±0.05),and p-Smad3/Smad3(0.65±0.06 vs 0.14±0.03),but notably decreased expression of Smad7 at mRNA(0.32±0.06 vs 1.02±0.09)and protein(0.19±0.03 vs 0.58±0.07)levels in the myocardial tissues(P＜0.05).The AF incidence and duration,CVF,miR-195-5p level,and protein levels of TGF-β1,Collagen-Ⅰ,Colla-gen-Ⅲ,p-Smad2/Smad2,and p-Smad3/Smad3 were significantly decreased,and the mRNA and protein levels of Smad7 were significantly increased in the miR-195-5p inhibitor group than the AF group and the negative control group(P＜0.05).The combined treatment increased the inci-dence and duration of AF,CVF,myocardial TGF-β1,Collagen-Ⅰ,Collagen-Ⅲ,p-Smad2/Smad2 and p-Smad3/Smad3 expression levels,and decreased the mRNA and protein expressions of Smad7 when compared with the miR-195-5p inhibitor group and the rAAV9 group(P＜0.05).Conclusion Down-regulation of miR-195-5p alleviates myocardial fibrosis in AF rats probably by targeting Smad7 to inhibit TGF-β1 signaling.
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