Role of microRNA-34a in anti-apoptotic effects of G-CSF in diabetic cardiomyopathy

Abstract

Background: Recent studies showed that microRNAs (miRNAs) are involved in the process of cardiomyocyte apoptosis. We previously reported that granulocyte-colony stimulating factor (G-CSF) ameliorated diastolic dysfunction and attenuated cardiomyocyte apoptosis in a rat model of diabetic cardiomyopathy. In this study, we hypothesized a regulatory role of cardiac miRNAs in the mechanism of the anti-apoptotic effect of G-CSF in the diabetic cardiomyopathy rat model. Methods: Rats were given a high-fat diet (HFD) and low-dose streptozotocin injection and then randomly allocated to receive treatment with either G-CSF or saline. H9c2 rat cardiomyocytes were cultured under a high glucose (HG) condition to induce diabetic cardiomyopathy in vitro. We examined the extent of apoptosis, extent of miRNA expression, and miRNA target gene for mRNA in myocardium in vivo and H9c2 cells in vitro, separately. Results: G-CSF treatment significantly decreased apoptosis and reduced miR-34a expression in diabetic myocardium and H9c2 cells under the HG condition. G-CSF treatment also significantly increased Bcl-2 protein expression as a target for miR-34a. In addition, transfection with miR-34a mimic significantly increased apoptosis and decreased Bcl-2 luciferase activity in H9c2 cells. Transfection with miR-34a inhibitor significantly decreased apoptosis in H9c2 cells. Conclusion: Our results indicate that G-CSF might have an anti-apoptotic effect through down-regulation of miR-34a in a diabetic cardiomyopathy rat model.