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

Life Sci. 2017 Jan 1:168:28-37. doi: 10.1016/j.lfs.2015.12.054. Epub 2016 Jan 5.

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.

Keywords: Apoptosis; Endothelial cells; Kv1.5; Mitochondria; Palmitate; T2DM.

MeSH terms

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

Substances

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