Molecular mechanism underlying the regulation of microRNA-20a on regulating glucose metabolism in cardiomyocytes

Objective To investigate the effect of microRNA-20a (miR-20a) on glucose metabolism in H9C2 cardiomyocytes, and reveal the mechanism of miR-20a on regulating insulin resistance and metabolic diseases. Methods The H9C2 cardiomyocytes was taken as the research object to establish the cell model of insulin resistance. The differential expression level of microRNAs was detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The miRanda was applied to screen complementary binding sites between microRNA and Glut4 3′UTR. The H9C2 cells were transfected with miR-20a mimic and negative control (NC), the insulin resistant cells were transfected with miR-20a inhibitor and relative NC, respectively. To apply qRT-PCR for detecting expression levels of miR-20a and Glut4 mRNA. Western blotting was used to detect expression level of Glut4 protein in each group. Glucose consumption and uptake assay were used to measure glucose metabolism level in each group. Data were analyzed with one-way analysis of variance test or t test. Results Compared with control group, the expression of miR-20a was significantly increased in insulin resistance group (3.14±0.12 vs 1.00±0.00, t= 17.79, P<0.01), the Glut4 mRNA and protein levels were obviously decreased in insulin resistance group (0.58±0.09 vs 1.00±0.00, t=4.71, P<0.05; 0.29±0.04 vs 1.00±0.00, t=17.18, P<0.01). There were complementary binding sites between miR-20a and Glut4 3′UTR. Compared with control group, the Glut4 mRNA and protein levels were decreased in miR-20a mimic group (0.36±0.11 vs 1.00±0.00, t=5.79, P<0.05; 0.25±0.05 vs 1.00±0.00, t=13.87, P<0.01). Glucose consumption and uptake levels were lower than those of control group respectively (48.74±3.95 vs 100.00±0.00, t=12.97, P<0.01; 211.30±13.30 vs 350.30±24.55, t=9.77, P<0.05). The Glut4 mRNA and protein levels were obviously increased in miR-20a inhibitor group compared with insulin resistance group (3.63±0.31 vs 1.00±0.00, t=8.39, P<0.01; 3.28±0.41 vs 1.00±0.00, t=5.55, P<0.05). Glucose consumption and uptake levels were increased than those of insulin resistance group respectively (240.30±34.12 vs 100.00±0.00, t=3.77, P<0.05; 267.70±31.86 vs 122.10±12.94, t=4.33, P<0.05). Conclusion MicroRNA-20a may affect glucose metabolism level of normal and insulin resistant H9C2 cardiomyocytes by regulating Glut4 expression. Key words: Glucose transporter protein 4; H9C2 cells; MicroRNA-20a; Glucose metabolism