MiR-124 promotes ischemia-reperfusion induced cardiomyocyte apoptosis by targeting sphingosine kinase 1

Ischemia-reperfusion (IR) injury of cardiomyocyte contributes to the cardiac dysfunction following myocardial infarction (MI). MiRNAs have been found to play a vital role in the pathogenesis of myocardial IR injury. In this study, the role of miR-124 in the myocardial IR injury was examined.

Myocardial ischemia rats' model was established to examine the expression level of miR-124. The primary rat cardiomyocytes were isolated to determine in vitro oxygen-glucose deprivation and reoxygenation model. The expression of miR-124 was analyzed by quantitative Real Time-PCR (qRT-PCR). The cell viability was assessed by Cell Counting Kit-8 (CCK-8) and LDH release assay. Cell apoptosis was evaluated by flow cytometry. The expression of cleaved caspase-3, Bcl-2, and Bax was assessed by Western blot. The expression of miR-124 was manipulated by transfection with miR-124 mimics and inhibitors. The Luciferase activity assay was performed to verify whether SphK1 was a direct target of miR-124. The mRNA and protein expression of SphK1 was assessed by qRT-PCR and Western blot. The ectopic expression of SphK1 was achieved by transfecting with overexpressing plasmid.

Our results showed that miR-124 expression was elevated in the infarct zone. The expression level of miR-124 following OGD/R was also significantly increased. Our results showed that miR-124 mimics could enhance OGD/R-induced miR-124 increase while miR-124 inhibitors performed the opposite effect. Our findings also revealed that miR-124 mimics could augment OGD/R-induced cell death and apoptosis, while miR-124 inhibitors expressed the opposite effect. SphK1 was proposed to be a direct target of miR-124. SphK1 overexpression could abrogate the augmenting activities of miR-124 on OGD/R-induced cell injury.

In the pathogenesis of MI, miR-124 promotes myocardial IR-induced cell death and apoptosis in cardiomyocyte by targeting SphK1.