title: Pharmacological activation of AMPK prevents Drp1-mediated mitochondrial fission and alleviates endoplasmic reticulum stress-associated endothelial dysfunction.
abstract: OBJECTIVE
  This study aims to investigate whether and how pharmacological activation of AMP-activated protein kinase (AMPK) improves endothelial function by suppressing mitochondrial ROS-associated endoplasmic reticulum stress (ER stress) in the endothelium. Experimental approach Palmitate stimulation induced mitochondrial fission and ER stress-associated endothelial dysfunction. The effects of AMPK activators salicylate and AICA riboside (AICAR) on mitochondrial ROS production, Drp1 phosphorylation, mitochondrial fission, ER stress, thioredoxin-interacting protein (TXNIP)/NLRP3 inflammasome activation, inflammation, cell apoptosis and endothelium-dependent vasodilation were observed. Key results "Silencing" of TXNIP by RNA interference inhibited NLRP3 inflammasome activation in response to ER stress, indicating that TXNIP was a key link between ER stress and NLRP3 inflammasome activation. AMPK activators salicylate and AICAR prevented ROS-induced mitochondrial fission by enhancing dynamin-related protein 1 (Drp1) phosphorylation (Ser 637) and thereby attenuated IRE-1α and PERK phosphorylation, but their actions were blocked by knockdown of AMPK. Salicylate and AICAR reduced TXNIP induction and inhibited NLRP3 inflammasome activation by reducing NLRP3 and caspase-1 expression, leading to a reduction in IL-1β secretion. As a result, salicylate and AICAR inhibited inflammation and reduced cell apoptosis. Meanwhile, salicylate and AICAR enhanced eNOS phosphorylation and restored the loss of endothelium-dependent vasodilation in the rat aorta. Immunohistochemistry staining showed that AMPK activation inhibited ER stress and NLRP3 inflammasome activation in the vascular endothelium.
  
  
  CONCLUSIONS
  Pharmacological activation of AMPK regulated mitochondrial morphology and ameliorated endothelial dysfunction by suppression of mitochondrial ROS-associated ER stress and subsequent TXNIP/NLRP3 inflammasome activation. These findings suggested that regulation of Drp1 phosphorylation by AMPK activation contributed to suppression of ER stress and thus presented a potential therapeutic strategy for AMPK activation in the regulation of endothelium homeostasis.
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China.
authors.forename: Yapu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Cellular and Molecular Biology Center of China Pharmaceutical University, Nanjing, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wen
authors.affiliation: Cellular and Molecular Biology Center of China Pharmaceutical University, Nanjing, China.
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Ma
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China.
authors.forename: Weijie
authors.initials: W
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Huang
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China.
authors.forename: Junping
authors.initials: J
authors.lastname: Kou
authors.affiliation: State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
authors.forename: Lian-Wen
authors.initials: LW
authors.lastname: Qi
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China.
authors.forename: Baolin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China; Department of Internal Medicine, Yale University School of Medicine, New Haven, USA. Electronic address: liukangxyz@gmail.com.
authors.forename: Kang
authors.initials: K
authors.lastname: Liu
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D000620:Aminoimidazole Carboxamide / Q000008:administration & dosage / Q000031:analogs & derivatives; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D020170:Caspase 1 / Q000096:biosynthesis; D018797:Cell Cycle Proteins; D034281:Dynamins / Q000096:biosynthesis* / Q000235:genetics; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007249:Inflammation / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D053583:Interleukin-1beta / Q000378:metabolism; D063154:Mitochondrial Dynamics / Q000187:drug effects; D051381:Rats; D012265:Ribonucleotides / Q000008:administration & dosage; D012459:Salicylates / Q000008:administration & dosage; D014664:Vasodilation / Q000187:drug effects
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C000594089:IL1B protein, rat; D053583:Interleukin-1beta; D012265:Ribonucleotides; D012459:Salicylates; C493796:TXNIP protein, rat; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; C568305:Prkaa1 protein, rat; D020170:Caspase 1; C519851:Dnm1l protein, rat; D034281:Dynamins; C031143:AICA ribonucleotide
keywords: AMPK; Endoplasmic reticulum stress; Endothelial dysfunction; Mitochondrial fission; NLRP3 inflammasome