BackgroundThe participation of long noncoding RNAs (lncRNAs) in myocardial infarction has recently been noted. However, their underlying roles in the border zone of myocardial infarction remain unclear. This study uses microarrays to determine the profiles of lncRNAs and mRNAs in the border zone.MethodsBioinformatics methods were employed to uncover their underlying roles. Highly dysregulated lncRNAs was further validated via PCR.ResultsFour hundred seven lncRNAs and 752 mRNAs were upregulated, while 132 lncRNAs and 547 mRNAs were downregulated in the border zone of myocardial infarction. A circos graph was constructed to visualize the chromosomal distribution and classification of the dysregulated lncRNAs and mRNAs. The upregulated mRNAs in the border zone were most highly enriched in cytokine activity, binding, cytokine receptor binding and related processes, as ascertained through Go analysis. Pathway analysis of the upregulated mRNAs showed the most significant changes were in the TNF signaling pathway, cytokine–cytokine receptor interaction and chemokine signaling pathway and similar pathways and interactions. An lncRNA–mRNA co-expression network was established to probe into the underlying functions of the 10 most highly dysregulated lncRNAs based on their co-expressed mRNAs. In the co-expression network, we found 16 genes directly involved in myocardial infarction, including Alox5ap, Itgb2 and B4galt1. The lncRNAs AY212271, EF424788 and MRAK088538, among others, might be associated with myocardial infarction. BC166504 is probably a key lncRNA in the border zone of myocardial infarction.ConclusionsThe results may have revealed some aberrantly expressed lncRNAs and mRNAs that contribute to the underlying pathophysiological mechanisms of myocardial infarction.
Background: Myocardial infarction (MI) refers to a fatal disease, and the border zone (BZ) of myocardial infarction is of high importance to the prognosis of myocardial infarction patients. Autophagy and apoptosis can significantly impact cardiovascular diseases. In the previous studies conducted by the authors, plenty of differential expressions of long non-coding RNA (lncRNA) were reported in the border zone of myocardial infarction. As revealed from the results of bioinformatics analysis, LncRNA may take up a vital part in the pathological process of cardiovascular disease by regulating apoptosis and autophagy. This study aimed to firstly conduct bioinformatics analyses to predict that NR_027324, as a competitive endogenous RNA (ceRNA), binds to miR-103-3p and subsequently regulates the expression of downstream target gene ATG5, to secondly verify the mentioned regulatory relationship by molecular biological experiments, and thirdly to investigate that the above pathways transmit apoptosis and autophagy signals in cardiomyocytes during hypoglycemic and anoxic injuries. Methods: The binding of NR_027324 to miR-103-3p was predicted by the bioinformatics analysis, and then the expression of downstream ATG5 was regulated. By the dual luciferase assay, the binding of NR_027324 to miR-103-3p was confirmed. H9c2 cells underwent the culture under low glucose and hypoxia to simulate cardiomyocytes under ischemia. NR_027324 siRNA and overexpression plasmid vector and miR-103-3p (mimics and inhibitors) were adopted to transfect cells to examine its function in cardiomyocytes. By the reverse transcription-quantitative polymerase chain reaction (RT-PCR), the expression levels of NR_027324, miR-103a-3p and ATG5 were assessed. Cell viability was measured by the MTT assay, and cell injury was analyzed by the lactate dehydrogenase assay (LDH). The western blotting assay was performed to detect the expressions of Bcl2, Bax, Atg5, cleaved-caspase3 and cleaved-caspase9. Moreover, the immunofluorescence assay was used to detect the expression of LC3-I/II as a marker of autophagy.Results: In hypoglycemic and anoxic H9C2 cells, the expressions of NR_027324 and ATG5 were up-regulated, while miR-103-3p showed a down-regulated expression. By the dual luciferase assay, the binding of NR_027324 to miR-103-3p was confirmed. The overexpressed NR_027324 could enhance the reduced cell viability of hypoglycemic and anoxic H9C2 cells and reduce cell damage. Interfering with the expression of NR_027324 could further reduce the viability of hypoglycemic anoxic H9C2 cells, increase injury, inhibit protective autophagy and accelerate apoptosis of hypoglycemic anoxic H9C2 cells. The mentioned pathophysiological processes were achieved by NR_027324 binding to miR-103-3p and then regulating the expression of target gene ATG5.Conclusion: In hypoglycemic and anoxic H9C2 cells, the expressions of NR_027324 and ATG5 are up-regulated, while the expression of miR-103-3p decreases. NR_027324 acts as ceRNA combined with miR-103-3p to regulate ATG5 and control autophagy and apoptosis in cardiomyocytes during hypoglycemic and anoxic injuries.
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