title: Constitutive activation of AMPK α1 in vascular endothelium promotes high-fat diet-induced fatty liver injury: role of COX-2 induction.
abstract: OBJECTIVE
  AMP-activated protein kinase (AMPK), an important regulator of energy metabolism, comprises three (α, β and γ) subunits, each with a unique tissue distribution. As AMPK has a wide range of protein and gene targets, defining its role has been difficult. Here, we have studied a transgenic mouse model overexpressing the constitutively active α1 subunit of AMPK in endothelial cells (EC-AMPK) to elucidate its role in energy homeostasis.
  
  
  METHODS
  Wild-type and EC-AMPK mice were fed with a high fat diet for 16 weeks. Drugs (or vehicles) were given daily by oral gavage. Body weight, fat mass composition, glucose and lipid levels were monitored regularly. Tissues including aortae and liver were collected for quantitative RT-PCR, Western blotting, elisa, histological and biochemical evaluations.
  
  
  RESULTS
  Compared with wild-type animals, high fat diet caused more severe metabolic defects in EC-AMPK mice, which exhibited increased body weight and fat mass, elevated blood pressure, augmented glucose and lipid levels, impaired glucose tolerance, hepatomegaly and steatohepatitis. Constitutive activation of AMPK α1 in endothelial cells induced COX-2 expression and arterial inflammation. Genes involved in lipid metabolism were down-regulated in aortae and livers of EC-AMPK mice. Chronic treatment with selective COX-2 inhibitors, celecoxib or nimesulide, significantly ameliorated arterial inflammation, steatohepatitis and hyperlipidaemia in EC-AMPK mice, without altering their blood pressure or clotting.
  
  
  CONCLUSIONS
  Constitutive activation of endothelial AMPK α1 promotes vascular inflammation and the development of obesity-induced fatty livers largely via induction of COX-2.
authors.affiliation: Department of Pharmacology and Pharmacy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liang
authors.forename: Bosheng
authors.initials: B
authors.lastname: Huang
authors.forename: Erfei
authors.initials: E
authors.lastname: Song
authors.forename: Bo
authors.initials: B
authors.lastname: Bai
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology; D001158:Arteries / Q000187:drug effects / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D015153:Blotting, Western; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D059305:Diet, High-Fat; D004591:Electrophoresis, Polyacrylamide Gel; D042783:Endothelial Cells / Q000187:drug effects / Q000473:pathology; D004730:Endothelium, Vascular / Q000187:drug effects*; D004790:Enzyme Induction / Q000187:drug effects; D005234:Fatty Liver / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D005951:Glucose Tolerance Test; D006529:Hepatomegaly / Q000139:chemically induced / Q000473:pathology; D008099:Liver / Q000166:cytology / Q000473:pathology / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009765:Obesity / Q000150:complications; D016133:Polymerase Chain Reaction
chemical_list: D001786:Blood Glucose; D051546:Cyclooxygenase 2; C548179:Prkaa1 protein, mouse; D055372:AMP-Activated Protein Kinases
keywords: AMPK; cyclooxygenase-2; endothelial cells; fatty liver injury