Suppression of Kv1.5 protects against endothelial apoptosis induced by palmitate and in type 2 diabetes mice.

AIMS

Palmitate, a common saturated free fatty acid, induces endothelial apoptosis in vitro in culture endothelial cells and in vivo in type 2 diabetes mellitus (T2DM) patients. The present study aimed to investigate whether Kv1.5 regulates palmitate-induced endothelial apoptosis and endothelial dysfunction in T2DM.

MAIN METHODS

In vitro experiments were carried out in primary human HUVECs. Apoptosis was analyzed by flow cytometry. Cell viability was determined by Cell Counting Assay Kit-8. The siRNA transfection was employed to knockdown Kv1.5 protein expression. Intracellular and mitochondrial ROS, and mitochondrial membrane potential were detected using fluorescent probes. Male C57BL/6 mice fed with high-sucrose/fat diet were injected with streptozotocin (35mg/kg body weight) to establish T2DM animal model.

KEY FINDINGS

We found that palmitate-induced endothelial apoptosis was parallel to a significant increase in endogenous Kv1.5 protein expression in endothelial cells. Silencing of Kv1.5 with siRNA reduced palmitate-induced endothelial apoptosis, intracellular ROS generation, mitochondrial ROS generation and membrane potential (Δψ) alteration and cleaved caspase-3 protein expression; while increased cell viability and ratio of Bcl-2/Bax. Furthermore, we observed that Kv1.5 protein expression increased in endothelial cells of thoracic aorta of T2DM mice. Silencing of Kv1.5 significantly improved the endothelium-dependent vasodilation in thoracic aortic rings of T2DM mice.

SIGNIFICANCE

These results demonstrate that suppression of Kv1.5 protects endothelial cells against palmitate-induced apoptosis via inhibiting mitochondria-mediated excessive ROS generation and apoptotic signaling pathway, suggesting that Kv1.5 may serve as a therapeutic target of treatment for endothelial dysfunction induced by palmitate and lipid metabolism in T2DM patients.