Role Of MicroRNA-200a In Proliferation And Activation Of Cardiac Fibroblasts In Rats

Objective Atrial fibrillation(AF)is a highly prevalent sustained chronic cardiac arrhythmia with high morbidity and mortality that can cause or exacerbate heart failure and is an important risk factor for stroke.The underlying mechanisms involved in the development of AF have yet not be fully elucidated.Micro RNAs(mi RNAs)represent a sizable sub-group of small non-coding RNAs,regulating gene expression and playing an important role in a wide range of biologic processes.Clinically,there is increasing evidence of the potential diagnostic role of mi RNAs as biomarkers.This study aimed at assessing the change of microRNA-200 a and its target gene SIRT1 expression changes of atrial fibrillation fibrosis in rats model to explore the effect of microRNA-200 a mimics on activation and proliferation of cardiac fibroblasts,Further defining microRNA-200 a molecular mechanism of playing a role in the process of myocardial fibrosis.Methods The model of myocardial fibrosis of SD rats was induced in the way of injecting isoprenaline(ISO)on the hypogastrium.80 SPF rats were randomly divided into the blank control group and the model group at random,which are repectively 40 and 40.The SD rats in model group were treated with injecting beneath the skin with ISO and the blank control group was treated with same quantity of normal saline.The rats were killed and took out hearts and obtained specimens.Cardiac fibroblasts cultured in vitro were transfected with microRNA-200 a mimics by LipofectamineTM2000 Reagent.After 36~48 h the indicators were assessed.HE staining and Masson staining were used to observed the degree of fibrosis and collagen volume fraction(CVF)in each group;The expression of microRNA-200 a and the m RNA of SIRT1 and ?-SMA were measured in q RT-PCR;The expression of SIRT1 and ?-SMA was determined by Western blot;MTT assay was used to detected the proliferation influence of the transfected cardiac fibroblasts by using microRNA-200 a mimics,inhibitor and their negative control.Results In two groups,the results of HE staining and Masson staining showed that the SD rats in model group appeared clearly collagen fiber hyperplasia in the mesenchyme and myocardial matrix collagen volume fraction(CVF)increased significantly.Compared with the blank control group,The expression of microRNA-200 a is decreased and the m RNA expression of SIRT1 and ?-SMA is increased.The protein expression of SIRT1 and ?-SMA is increased.Compared with blank control group and the negative control group,microRNA-200 a is increased.The expression of microRNA-200 a was up-regulated while SIRT1 and ?-SMA expressed declinedly in the group of transfecting microRNA-200 a mimics.Cardiac fibroblasts proliferation was suppressed by transfecting transiently microRNA-200 a mimics.Conclusion Atrial fibrillation and obvious myocardial fibrosis can be induced by subcutaneous injection of ISO in rats.The high expression of microRNA-200 a results in the decrease of the SIRT1 and ?-SMA expression,inhibiting myocardial fibrosis.Micro RNA-200 a mimics can inhibit myocardial fibroblasts proliferation activity.It is included that microRNA-200 a can be a potential targets for treatment of myocardial fibrosis and the application of its regulator will provide the new idea and method for the prevention and cure of myocardial fibrosis.