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

Abstract

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 (Δψm) 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.

• Authors: Jie-Yi Du, Feng Yuan, Li-Yan Zhao, Jie Zhu, Yun-Ying Huang, Gen-Shui Zhang, Yi Wei, Yun Liu, Quan Yi, Yong-Sheng Tu, Xiao Zhong, Fang-Yun Sun, Hong-Shuo Sun, Yong-Yuan Guan, Wen-Liang Chen, Guan-Lei Wang
• Journal: Life sciences (Life Sci) Vol. 168 Pg. 28-37 (Jan 01 2017) ISSN: 1879-0631 [Electronic] Netherlands
• PMID: 26764232 (Publication Type: Journal Article)
• Copyright: Copyright © 2016 Elsevier Inc. All rights reserved.

Chemical References

• Kv1.5 Potassium Channel
• Palmitates
• RNA, Small Interfering
• Reactive Oxygen Species

Topics

• Animals
• Aorta (metabolism, physiopathology)
• Apoptosis
• Cell Survival
• Diabetes Mellitus, Type 2 (genetics, metabolism, pathology, physiopathology)
• Endothelial Cells (cytology, metabolism, pathology)
• Human Umbilical Vein Endothelial Cells
• Humans
• Kv1.5 Potassium Channel (genetics, metabolism)
• Male
• Membrane Potential, Mitochondrial
• Mice, Inbred C57BL
• Palmitates (metabolism)
• RNA Interference
• RNA, Small Interfering (genetics)
• Reactive Oxygen Species (metabolism)
• Vasodilation