The Mechanism Of The Long Noncoding RNA Regulating Cardiomyocyte Apoptosis In The Border Zone Of Myocardial Infarction In Rats

Objective: Myocardial infarction（MI）is a fatal disease that causes millions of death worldwide every year.Border zone（BZ）of the myocardial infarction is crucial to patients.Lnc RNAs were considered to be “noise” of transcription without biological functions.But in recent years,lnc RNAs have been found to play important roles in all kinds of biological processes,especially in cardiovascular diseases.However,the potential roles of lnc RNAs in the border zone of myocardial infarction remain unclear.The aim of our study was to obtain a global expression profile of lnc RNAs and m RNAs of the border zone in Wistar rats myocardial infarction,and identify the changes during myocardial infarction.Accorrding to the functions of co-expressed m RNAs,we predict the potential functions of lnc RNAs.The experiment confirms that,the NR₀27324 directly targeted mi R-103-3p as ce RNA,which in turn regulates downstream ATG5 expression,and transmits apoptosis signals in the injury of myocardial cells in low glucose and hypoxia.Methods: The MI rat model was constructed by ligaturing the left anterior descending artery（LAD）,while the sham-operated rats underwent an identical procedure without tying.Rats were sacrificed at 6 h after ligation.Evans Blue dye（EB）and triphenyltetrazolium chloride（TTC）dual-dye staining was performed to determine precisely the border zone around the infarction region.In this study,we investigate the profile of lnc RNAs and m RNAs in BZ by microarray.Bioinformatics methods were employed to reveal their potential roles,such as GO analysis,pathway analysis and co expression network analysis.Highly-dysregulated lnc RNAs was further validated by polymerase chain reaction.We predicted NR₀27324 combined with mi R-103-3p to regulate downstream ATG5 expression by bioinformatics analysis.Then the dual luciferase reporter assay showed NR₀27324 binding with mi R-103-3p.Both m RNA expression levels and protein expression levels,indicated that NR₀27324 binding mi R-103-3p as ce RNA transmits apoptosis signals in the injury of myocardial cells in low glucose and hypoxia.Results: Totally 24529 lnc RNAs and m RNAs were detected in the array.Results showed that 407 lnc RNAs were up-regulated with Fold change >2 and P<0.05 compared with those in the sham operation group.Meanwhile,132 lnc RNAs were down-regulated（Fold change >2 and P<0.05）.752 m RNAs were up-regulated,547 m RNAs were down-regulated（Fold change >2 and P<0.05）.GO analysis results show that in the border zone of myocardial infarction,the upregulated m RNAs in BZ were most highly enriched in cytokine activity,binding,cytokine receptor binding,etc.While the downregulated m RNAs were most highly enriched in nervous system development,extracellular matrix part,protein binding,etc.In the border zone of myocardial infarction,the highest enrichment score of pathways in up-regulated m RNAs included TNF signaling pathway,Cytokine-cytokine receptor interaction pathway,meanwhile in down-regulated m RNAs contained Cell cycle pathway.To investigate the relationship and the potential modulating mechanism between the aberrantly expressed m RNAs and the differentially expressed lnc RNAs,we constructed a co-expression network.The net-work indicates one m RNA may be regulated by several lnc RNAs at the same time,while single lnc RNA also affects several m RNAs simultaneously.In low glucose and hypoxia H9C2 cells,NR₀27324,ATG5 expression was increased,and mi R-103-3p expression was down-regulated.The dual luciferase reporter assay confirmed that NR₀27324 bind to mi R-103-3p.NR₀27324 regulates the ATG5 expression by mi R-103-3p.Overexpression NR₀27324 reduces the vitality of low glucose and hypoxia H9C2 cells and promotes the expression of ATG5 and apoptosis-related gene proteins.Down-regulated NR₀27324 can enhance the vitality of low glucose and hypoxia H9C2 cells,inhibit apoptosis and autophagy of low glucose and hypoxia H9C2 cells.Conclusion: Lnc RNAs and m RNAs of the border zone in myocardial infarction Wistar rats were differentially expressed.The total number of differentially expressed annotated lnc RNAs in BZ was more than those in the MI zone.According to the bioinformation analysis of DE m RNAs and the co-expression network,we presume that lnc RNA in BZ may have potential roles in regulating inflammation,stress responses,cell proliferation,apoptosis and necrosis,energy metabolism,cardiomyocyte remodelling,ion channels,twitch aberration and scar attenuation.NR₀27324 binding mi R-103-3p as ce RNA to regulate ATG5,transmits apoptosis signals in the myocardial cells in low glucose and hypoxia damage.The results may provide evidence on the underlying mechanisms of aberrantly expressed lnc RNAs and m RNAs in pathophysiology of MI.