| The world health organization reports that coronary heart disease has become the world's leading cause of death.Acute myocardial infarction(AMI)is the death of myocardial cells caused by severe and persistent acute myocardial ischemia.Ventricular remodeling(VR)is a remodeling process of heart from gene to structure,metabolism and function under the combined action of hemodynamics,neurohumors and other factors after myocardial infarction.Ventricular remodeling is the basic pathological process of heart failure(HF)after acute myocardial infarction,and it is the main reason to affect the prognosis of acute myocardial infarction.Therefore,how to slow down or reverse the ventricular remodeling after acute myocardial infarction and prevent the occurrence of heart failure is a major problem of secondary prevention of myocardial infarction.Long non-coding RNA(lncRNAs)are a class of transcription products that the transcript length over 200 nt.LncRNAs do not encode proteins themselves.They are initially considered to have no biological function.However,recent studies have shown that lncRNAs have a wide range of biological functions.They regulate gene expression in RNA form at many levels.It's to provide a new research field for exploring the pathological mechanism of complex diseases.In this study,we screened out differential expression of lncRNAs in myocardial tissue of ventricular remodeling rats after myocardial infarction by gene chip experiment,in order to find the target genes of ventricular remodeling specificity lncRNAs,and provide a new diagnostic basis and treatment method for ventricular remodeling.Objective:To screen the differential expression of lncRNAs and mRNAs in ventricular remodeling rats after myocardial infarction,and bioinformatics analysis was used to enrich the differential expression of mRNAs in functions and biological pathways aspects,then set up the lncRNAs-mRNAs coexpression network.Hope that find the target genes related to ventricular remodeling after myocardial infarction.Methods:1.Preparation of ventricular remodeling rats model after myocardialinfarctionIn this study,60 healthy male Sprague-Dawley(SD)rats [SPF level,body weight(200±20)g].After one week of adaptive feeding,selecting randomly 45 rats was to ligate the left anterior descending coronary artery for preparing acute myocardial infarction model.15 rats were treated with sham operation,that is,they were not ligated at the same position.10 rats were randomly selected from the ligated and survived rats as the model group.And 10 rats were randomly selected from sham operated and survived rats as sham operation group.The cardiac function of two groups of rats was detected by hemodynamics at 4 weeks after operation.Haematoxylin and Eosin(HE)staining and Masson trichrome were conducted to observe cardiac morphological pathology changes and the degree of myocardial fibrosis.2.Gene chips experimentFrom the model group and the sham operation group,three myocardial tissue samples were randomly selected to carry out gene chip experiments respectively.Extract the total RNAs of the myocardial tissue heart infarction area of the model group and in the same part of the sham operation group,then purify and test the quality of total RNAs.Carry out the chip hybridization experiment after synthesizing cDNA.Scan the chip images and normalize and analyze the chips data by the Agilent GeneSpring GX V11.5 software.Using box line graph are to evaluate the quality of chips data.Differential expression analysis,differential cluster analysis,scatter plot and volcano map were used to analyze the differential expression of lncRNAs and mRNAs,and get the summary information of differential expression of lncRNAs and mRNAs.KOBAS 3.0 was used to perform GO functional analysis,KEGG and PANTHER pathwy analysis for differentially expressed mRNAs.Using the Cytoscape 3.6.0 software was to construct the lncRNAs-mRNAs coexpression network.Results:1.Influence on heart functionCompared with the sham operation group,the left ventricular systolic pressure(LVSP)and the maximum increase and decrease rate of left ventricular pressure(± dp/dtmax)decreased significantly in the model group(p<0.01).Left ventricular end diastolic pressure(LVEDP)increased significantly(p<0.01).2.HE and Masson staining resultsHE staining showed that a large number of myocardial cells were necrotic in the myocardial tissue of the model group,the sham operation group's was normal;Masson staining showed that the myocardial collagen fibers in the model group increased significantly and formed flake-like distribution compared with the sham operation group,but the collagen fibers in the sham operation group were scattered between the cardiac myocytes.3.Gene chip quality evalutionThrough the box plot to analyze the chips data,the sample data have high similarity,and the quality of chips data is good.4.Differential expression of lncRNAs and mRNAsCompared with the sham operation group,74 lncRNAs were differentially expressed,account for 0.402% of total lncRNA probs.50 up regulated,24 down regulated.31 differentially expressed lncRNAs changed more than 2.5 times,22 up regulated and 9 down regulated.2 differentially expressed lncRNAs changed more than 5 times,2 up regulated.116 mRNAs were differentially expressed,account for 0.44% of total mRNA probs.99 up regulated,17 down regulated.5.Classification of functions and pathways of differential expression of mRNAs:The GO analysis took P<0.05 as the threshold,and there were 693 significant enrichments.The top 50 of terms,which may be associated with ventricular remodeling after myocardial infarction: cell surface receptor signaling pathway,immune system process,positive regulation of cytokine production,response to stimulus,regulation of cytokine production,cytokine production.The KEGG and PANTHER pathways were analyzed with P<0.05 as the threshold,and 42 pathways were obtained.Biological pathways associated with ventricular remodeling after myocardial infarction were: Rap1 signaling pathway,Cytokine-cytokine receptor interaction,Ras signaling pathway,NF-kappa B signaling pathway,MAPK signaling pathway,HIF-1 signaling pathway,Inflammatory mediator regulation of TRP channels.6.The lncRNAs-mRNAs coexpression network:Figure 15.A is a total network plot of a coexpression network built by 74 differentially expressed lncRNAs and 116 differentially expressed mRNAs.Figure A has 174 nodes and 1975 edges.The B,C,and D plots are the subnode graphs of the significant correlation of A.7.The determination of the purpose of research lnRNAsBy digging the lncRNAs-mRNAs co expression network,associated mRNAs and gene loci analysis,finally determined that 6 candidate lncRNAs: LOC103691864(up),NONRATT015650(up),NONRATT031004(up),NONRATT025704(down),LOC102552965(down),NONRATT012533(down)Conclusion:1.Compared with the sham operation group,there were 74 lncRNAs and 116 mRNAs differentially expressed in the myocardial tissue of the ventricular remodeling rats after the myocardial infarction.2.With GO,KEGG,and PANTHER Pathwy analysis of differentially expressed mRNAs on the KOBAS 3.0 platform,find some possible functions associated with ventricular remodeling after myocardial infarction: cell surface receptor signaling pathway,immune system process,positive regulation of cytokine production,response to stimulus,regulation of cytokine production,cytokine production.And the related approaches are: Rap1 signaling pathway,Cytokine-cytokine receptor interaction,Ras signaling pathway,NF-kappa B signaling pathway,MAPK signaling pathway,HIF-1 signaling pathway,Inflammatory mediator regulation of TRP channels.3.By the lncRNAs-mRNAs coexpression network analysis,associated mRNAs and gene loci analysis,finally determined that 6 candidate lncRNAs:LOC103691864(up),NONRATT015650(up),NONRATT031004(up),NONRATT025704(down),LOC102552965(down),NONRATT012533(down).In the follow-up experiments,these 6 lncRNAs will be validated in the ventricular remodeling rats model after myocardial infarction and be studied the functions and mechanisms. |
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