Effect of microRNA-133b on Myocardial Fibrosis / 中国医学科学院学报

ABSTRACT

Objective To investigate the effect of microRNA-133b(miR-133b)on cardiac fibrosis and its mechanism.Methods Human cardiac fibroblasts(CFs)were harvested.The proliferation of CFs was detected by CCK8 during the overexpression and knock-down of miR-133b.The expressions of connective tissue growth factor(CTGF),α-smooth muscle actin(α-SMA),collagen Ⅰ,and collagen Ⅲ were detected with qRT-PCR and Western blot analysis after miR-133b overexpression or downexpression.Target genes of miR-133b were predicted by bioinformatics software.Dual-luciferase activity assay were used to verify a target gene of miR-133b.Results qRT-PCR showed that the expression level of miR-133b in the miR-133b mimic group was significantly higher than that in the negative control group(=26.219,=0.000).The expression level of miR-133b in the miR-133b inhibitor group was significantly lower than that in the negative control group(=6.738,=0.003).After 21,45,69,93,and 117 hours of transfection,the proliferation ability of CFs significantly decreased in the miR-133b mimic group but significantly increased in the miR-133b group(all <0.05,compared with the negative control group).After overexpression of miR-133b,the mRNA and protein levels of CTGF(=9.213,=0.001;=8.195,=0.001),α-SMA(=6.511, =0.003;=4.434,=0.011),collagenⅠ(=3.172,=0.034;=4.053,=0.015)and collagen Ⅲ(=6.404,=0.003;=5.319,=0.006)were significantly down-regulated.After the expression of miR-133b was knocked down,the mRNA and protein levels of CTGF(=9.439,=0.001;=14.100,=0.000),α-SMA(=4.519,=0.011;=4.377,=0.012),collagen Ⅰ(=5.966,=0.004;=5.514,=0.005)and collagen Ⅲ(=4.622,=0.010;=4.996,=0.008)were significantly increased.The relative luciferase activity of the cells co-transfected with miR-133b mimic and WT 3'UTR expression vector was significantly lower than that of the cells co-transfected with mimic control and WT 3'UTR expression vectors(=5.654,=0.005);however,there was no significant difference in relative luciferase activity between cells co-transfected with miR-133b mimic and MUT 3'UTR expression vectors and cells co-transfected with mimic control and MUT 3'UTR expression vectors(=0.380,=0.724).Conclusion miR-133b may affect the activation and proliferation of CFs by targeting CTGF and thus improve cardiac fibrosis.