Microarray Analysis And Preliminary Mechanical Study Of Long Noncoding RNA In A Rat Model Of Post-infarct Cardiac Fibrosis

BackgroundWith the continuous improvement of technology and drug treatment,the mortality of patients with acute myocardial infarction(MI,Myocardial Infarction)has decreased significantly.However,the cardiovascular complications after MI did not decrease significantly,mainly due to the MI-induced left ventricular myocardial remodeling and consequent cardiac dysfunction.Exploring a more effective and accurate treatment is essential to improve myocardial remodeling and to further reduce the mortality and morbidity after MI.Previous studies suggest that myocardial fibrosis is one of the main pathophysiological features of adverse left ventricular remodeling after MI.Although the mechanism of myocardial fibrosis has been largely explored in recent years,the exact molecular mechanism is still unclear.In the past decade,long noncoding RNAs(lncRNA)are gaining increasing attention in the regulation of cardiovascular diseases,but studies of its role in cardiac fibrosis is still scantyObjectives:This study aims to use microarray to identify the expression profile of lncRNA in myocardial fibrosis after MI in a rat model,to screen lncRNAs that may be involved in myocardial fibrosis,and to preliminarily explore the functional role of lncRNA in myocardial fibrosis.Methods:Forty Sprague-Dawley male rats were divided into two groups:sham-operation group(n=20)and MI group(n=20).MI was induced by ligating the left anterior descending coronary artery of the animal.Four weeks after the operation,the cardiac functional parameters of rats in each group were evaluated by echocardiography.Masson staining was used to observe the degree of fibrosis of myocardial tissues in the sham operation group and MI group.Next,lncRNA microarray was used to detect the total RNAs extracted from myocardial tissues,and after purification,they were subjected to chip hybridization and comparative analysis of differential expression;at the same time,bioinformatic analysis was performed on differentially expressed lncRNAs,including GO analysis and KEGG pathway analysis.Quantitative polymerase chain reaction(qPCR,quantitative Polymerase Chain Reaction)method was used to detect the mRNA expression levels of target lncRNA and collagen Ⅰ/Ⅲin myocardial tissue,and Western Blot was used to detect the protein expression level of collagen Ⅰ/Ⅲ.Neonatal rat myocardial fibroblasts cultured in vitro with the angiotensin Ⅱ(Ang Ⅱ),and siRNAs were used to silence the target IncRNA.Then the protein expression of collagen I/III was detected using qPCR and Western Blot in order to understand the effect of target lncRNA on Ang Ⅱ-induced collagen expression.Results:1.Compared with the sham group,left ventricular weight,left ventricular weight index,left ventricular end-diastolic volume and left ventricular end-systolic volume were increased in the MI group.Masson staining showed a significant increase in the degree of fibrosis and the content of hydroxyproline(P<0.05).2.Microarray analysis showed that 215 lncRNAs were differentially expressed in rat fibrotic myocardial tissue,accounting for 1.402%of the total lncRNAs detected;112 of them were up-regulated and 103 were down-regulated.A total of 5 lncRNAs were up-regulated.The GO and KEGG pathway analysis showed that the differentially expressed lncRNAs are related to the function and signaling pathway of myocardial fibrosis.3.The results of microarray showed that the most significantly upregulated lncRNAs included Ang362,U57362,BC086588,H19,etc.In fibrotic myocardium in MI rats,qPCR further confirmed that Ang362 expression was significantly up-regulated,accompanied by significantly increased expression of collagen Ⅰ and collagen Ⅲ.4.In cardiac fibroblasts cultured in vitro,silencing the expression of lnc-Ang362 can significantly reduce the expression of collagen Ⅰ/Ⅲ induced by Ang Ⅱ.Conclusion:1.MI can cause significant myocardial fibrosis and decreased cardiac function in rats 2.Microarray analysis identified significantly differential expression profiles of lncRNAs in fibrotic myocardial tissue after infarction.Bioinformatics analysis indicates that these lncRNAs may be closely related to the regulation of extracellular matrix and related signaling pathways.3.The up-regulation of lnc-Ang362 expression is related to myocardial fibrosis in MI rats,and may be one of the regulatory factors in the process of up-regulation of collagen by Ang Ⅱ.