title: Low cytochrome oxidase 4I1 links mitochondrial dysfunction to obesity and type 2 diabetes in humans and mice.
abstract: OBJECTIVE
  Cytochrome oxidase (COX) dysfunction is associated with mitochondrial oxidative stress. We determined the association between COX expression, obesity and type 2 diabetes.
  
  
  METHODS
  COX4I1 and COX10 genes were measured in monocytes of 24 lean controls, 31 glucose-tolerant and 67 diabetic obese patients, and 17 morbidly obese patients before and after bariatric surgery. We investigated the effect of caloric restriction and peroxisome proliferator-activated receptor (PPAR) agonist treatment on Cox in obese diabetic mice, and that of diet-induced insulin resistance in Streptozotocin-treated mice.
  
  
  RESULTS
  Low COX4I1 was associated with type 2 diabetes in obese patients, adjusting for age, gender, smoking, interleukin-6 and high-sensitivity C-reactive protein, all related to metabolic syndrome (MetS; odds ratio: 6.1, 95% confidence interval: 2.3-16). In contrast, COX10 was low in glucose-tolerant and diabetic obese patients. In morbidly obese patients, COX4I1 was lower in visceral adipose tissue collected at bariatric surgery. In their monocytes, COX4I1 decreased after bariatric surgery, and low COX4I1 at 4 months was associated with MetS at 7 years. In leptin-deficient obese diabetic mice, Cox4i1 was low in white visceral adipose tissue (n=13; P<0.001) compared with age-matched lean mice (n=10). PPARγ-agonist treatment (n=13), but not caloric restriction (n=11), increased Cox4i1 (P<0.001). Increase in Cox4i1 depended on the increase in glucose transporter 4 (Glut4) expression and insulin sensitivity, independent of the increase in blood adiponectin. In streptozotocin-treated mice (three groups of seven mice, diet-induced insulin resistance decreased Cox4i1 and Glut4 (P<0.001 for both).
  
  
  CONCLUSIONS
  COX4I1 depression is related to insulin resistance and type 2 diabetes in obesity. In peripheral blood monocytes, it may be a diagnostically useful biomarker.
authors: Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium.
authors: B
authors: B
authors: Van der Schueren
authors: Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium.
authors: R
authors: R
authors: Vangoitsenhoven
authors: Division of Atherosclerosis and Metabolism, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors: B
authors: B
authors: Geeraert
authors: Division of Atherosclerosis and Metabolism, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors: D
authors: D
authors: De Keyzer
authors: Division of Atherosclerosis and Metabolism, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors: M
authors: M
authors: Hulsmans
authors: Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium.
authors: M
authors: M
authors: Lannoo
authors: Division of Atherosclerosis and Metabolism, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors: H J
authors: HJ
authors: Huber
authors: Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium.
authors: C
authors: C
authors: Mathieu
authors: Division of Atherosclerosis and Metabolism, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors: P
authors: P
authors: Holvoet
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics*; D000818:Animals; D050110:Bariatric Surgery; D003921:Diabetes Mellitus, Experimental; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000503:physiopathology*; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000235:genetics*; D014644:Genetic Variation; D006801:Humans; D007333:Insulin Resistance / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008820:Mice, Obese; D008928:Mitochondria / Q000235:genetics / Q000473:pathology*; D009767:Obesity, Morbid / Q000235:genetics / Q000503:physiopathology*; D015431:Weight Loss
chemical_list: D008565:Membrane Proteins; C490115:COX10 protein, human; C000604261:Cox4i1 protein, mouse; D003576:Electron Transport Complex IV; D019883:Alkyl and Aryl Transferases; C512252:COX10 protein, mouse