title: Adipose tissue dysfunction in humans: a potential role for the transmembrane protein ENPP1.
abstract: BACKGROUND
  Adipose tissue (AT) helps to regulate body fat partitioning and systemic lipid/glucose metabolism. We have recently reported lipid/glucose metabolism abnormalities and increased liver triglyceride content in an AT-selective transgenic model overexpressing ectonucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1), the AdiposeENPP1-Tg mouse.
  
  
  OBJECTIVE
  The aim of the study was to test the translational hypothesis that AT-ENPP1 overexpression associates with AT dysfunction (changes in AT gene expression, plasma fatty acid, and adipokine levels), increased liver triglyceride deposition, and systemic insulin resistance in humans.
  
  
  METHODS
  A total of 134 young normoglycemic men and women were subjected to body composition studies, hyperinsulinemic-euglycemic clamps, and AT needle biopsy. Twenty men also had liver/muscle nuclear magnetic resonance spectroscopy.
  
  
  METHODS
  Predetermined measures included AT expression of ENPP1 and other lipid metabolism/inflammation genes, plasma adipokines, and nonesterified fatty acid (NEFA) levels, liver/muscle triglyceride content, and the systemic glucose disposal rate.
  
  
  RESULTS
  After statistical adjustment for body fat content, increasing AT-ENPP1 was associated with up-regulation of genes involved in NEFA metabolism and inflammation, increased postabsorptive NEFA levels, decreased plasma adiponectin, increased liver triglyceride content, and systemic insulin resistance in men. In women, there were no changes in plasma adiponectin, NEFAs, or glucose disposal rate associated with increasing AT-ENPP1, despite increased expression of lipid metabolism and inflammation genes in AT.
  
  
  CONCLUSIONS
  Increased AT-ENPP1 is associated with AT dysfunction, increased liver triglyceride deposition, and systemic insulin resistance in young normoglycemic men. These findings are concordant with the AdiposeENPP1-Tg phenotype and identify a potential target of therapy for health complications of AT dysfunction, including type 2 diabetes and cardiovascular disease.
authors.affiliation: Department of Medicine, Division of Endocrinology, University of Texas Medical Branch at Galveston, Texas 77555-1060, USA.
authors.forename: Manisha
authors.initials: M
authors.lastname: Chandalia
authors.forename: Himara
authors.initials: H
authors.lastname: Davila
authors.forename: Wentong
authors.initials: W
authors.lastname: Pan
authors.forename: Magdalena
authors.initials: M
authors.lastname: Szuszkiewicz
authors.forename: Demidmaa
authors.initials: D
authors.lastname: Tuvdendorj
authors.forename: Edward H
authors.initials: EH
authors.lastname: Livingston
authors.forename: Nicola
authors.initials: N
authors.lastname: Abate
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism / Q000502:physiology*; D000328:Adult; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance / Q000235:genetics / Q000502:physiology; D050356:Lipid Metabolism / Q000235:genetics; D052439:Lipid Metabolism Disorders / Q000150:complications / Q000235:genetics* / Q000503:physiopathology*; D008099:Liver / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases