Objective To explore the impact and mechanism of circ-HIPK3 on acute myocardial infarction(AMI).Methods C57BL/6 mice were randomly divided into sham operation group and AMI group,with 10 mice in each group.The AMI model was constructed by ligation of the left anterior descending branch of the left coronary artery.The primary cardiomyocytes were isolated and the hypoxia model was constructed in vitro.The apoptosis of cardiomyocytes was detected with the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay.Quantitative real-time polymerase chain reaction was used to measure the expression levels of circ-HIPK3 and miR-215.The expressions of forkhead box protein O1(FOXO1),B-cell lymphoma-2(Bcl-2),Bcl2-associated X protein(Bax)and Cleaved caspase-3 were detected by Western blot.Dual luciferase reporter gene assay was used to detect the interaction between miR-215 and FOXO1.Results Compared with sham operation group,the cardiac histopathological changes of AMI group were obvious,the number of apoptotic cells was increased,the expression levels of circ-HIPK3 and FOXO1 were elevated,and the level of miR-215 decreased,with all statistical significance(all P＜0.01).In vitro hypoxic culture of cardiac myocytes also showed similar changes(all P＜0.01).After circ-HIPK3 knockdown,the viability of cardiomyocytes increased,the number of apoptotic cells decreased,the expression levels of Bcl-2 increased,and the expression levels of Bax and Cleaved caspase-3 decreased,with all statistical significance(all P＜0.01).There were binding sites between miR-215 and FOXO1.Dual luciferase reporter gene assay confirmed that FOXO1 was the downstream target gene of miR-215,and its expression was regulated by miR-215.Compared with the hypoxia group,the hypoxia+si-FOXO1(knockdown FOXO1)group exhibited increased cell viability,reduced apoptotic cell count,increased Bcl-2 expression,and decreased expression levels of Bax and Cleaved caspase-3,with all statistical significance(all P＜0.01).After transfection with circ-HIPK3 overexpression plasmid,the effect of si-FOXO1 on hypoxic cardiomyocytes was reversed(all P＜0.01).Conclusion circ-HIPK3 promotes the expression of FOXO1 by regulating miR-215,thus enhancing myocardial cell apoptosis and promote the occurrence and development of AMI.
circ-HIPK3miR-215Forkhead box protein O1Acute myocardial infarction
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