Exercise ameliorates endothelial dysfunction in type2-diabetic mice through increasing microRNA-181b level via AMPK pathway

抄録

Background

Endothelial dysfunction plays an essential role in the pathogenesis of diabetic vascular diseases. Our previous studies showed that exercise ameliorates endothelial dysfunction by inhibiting ER stress and increasing nitric oxide production. 5' AMP-activated protein kinase is one of the mediators for the beneficial effect of exercise in the vasculature. MicroRNA 181b (miR-181b) was reported to improve glucose homeostasis and insulin sensitivity by regulating endothelial function. However, whether miR-181b is regulated by exercise and AMPK remains unclear. Therefore, we aim to investigate the regulation of miR-181b expression by exercise and AMPK and the role of miR-181b in mediating the beneficial effect of exercise.

Methods and results

To investigate whether exercise upregulates miR-181b expression, we subjected the diabetic mice to treadmill exercise for 45 min per day for two months. Thereafter, miR-181 expression in mouse aorta was determined by quantitative real-time PCR. The result shows that exercise significantly increases miR-181b level in mice aorta compared to that from sedentary mice. To examine the impact of blood flow on miR-181b, we tested the effect of laminar flow on miR-181b expression in Human Umbilical Vein Endothelial Cells. The result shows laminar flow significantly increased miR-181b expression. To show whether AMPK mediated laminar flow induced miR-181b expression, we treated the HUVECs with AMPK agonist 5-aminoimidazole-4-carboxamide ribonucleotide for different time points. The result shows AICAR significantly induces miR-181b expression with the peaks at eight hours which can be reversed by AMPK inhibitor compound C. In addition, glucose transporter inhibitor 2-Deoxy-D-glucose also increased the miR-181b level. Consistently, HUVECs transfected with the active form of AMPK upregulated miR-181b expression. To examine whether miR-181b has a beneficial effect on endothelial function in diabetic mice, we infected db/db mice with the adenovirus expressing miR-181b. The result shows miR-181b over-expression improves endothelial function in db/db mice accompanied by decreased vascular inflammation and increased eNOS expression in mouse arteries.

Conclusion

Exercise increases miR-181b level in mouse endothelium via laminar shear stress-induced AMPK activation. MiR-181b improves endothelial function in diabetic mice by inhibiting vascular inflammation and increasing eNOS expression. MiR-181b may serve as a therapeutic target for the treatment of diabetic vasculopathy.