title: Suppression of Kv1.5 protects against endothelial apoptosis induced by palmitate and in type 2 diabetes mice.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.affiliation: Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Jie-Yi
authors.initials: JY
authors.lastname: Du
authors.affiliation: Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Yuan
authors.affiliation: Department of Pharmacy, The First Affiliated Hospital, Sun Yat-sent University, Guangzhou 510080, China.
authors.forename: Li-Yan
authors.initials: LY
authors.lastname: Zhao
authors.affiliation: Department of Neurosurgery, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Pharmacy, The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou 510080, China.
authors.forename: Yun-Ying
authors.initials: YY
authors.lastname: Huang
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China.
authors.forename: Gen-Shui
authors.initials: GS
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Yi
authors.affiliation: Department of Physiology, Guangzhou Medical University, Guangzhou 511436, China.
authors.forename: Yong-Sheng
authors.initials: YS
authors.lastname: Tu
authors.affiliation: Department of Paediatrics, Nanfang Hospital, Southern Medical University, No. 1838 Guangzhou Avenue North, Guangzhou 510515, Guangdong, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhong
authors.affiliation: Lab for Basic Research of Life Science, School of Medicine, Tibet Institute for Nationalities, Xianyang 712082, China.
authors.forename: Fang-Yun
authors.initials: FY
authors.lastname: Sun
authors.affiliation: Departments of Surgery, Physiology, Pharmacology, Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto M5S 1A8, Canada.
authors.forename: Hong-Shuo
authors.initials: HS
authors.lastname: Sun
authors.affiliation: Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Yong-Yuan
authors.initials: YY
authors.lastname: Guan
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China. Electronic address: febright@126.com.
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China; Guangdong Province Key Laboratory of Functional Molecules in Oceanic Microorganism, Sun Yat-sen University, Department of Education of Guangdong Province, Guangzhou, China. Electronic address: wangglei@mail.sysu.edu.cn.
authors.forename: Guan-Lei
authors.initials: GL
authors.lastname: Wang
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000503:physiopathology; D017209:Apoptosis; D002470:Cell Survival; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D051666:Kv1.5 Potassium Channel / Q000235:genetics / Q000378:metabolism*; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008810:Mice, Inbred C57BL; D010168:Palmitates / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D014664:Vasodilation
chemical_list: D051666:Kv1.5 Potassium Channel; D010168:Palmitates; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species
keywords: Apoptosis; Endothelial cells; Kv1.5; Mitochondria; Palmitate; T2DM