title: IL-6 indirectly modulates the induction of glyceroneogenic enzymes in adipose tissue during exercise.
abstract: BACKGROUND
  Glyceroneogenesis is an important step in the control of fatty acid re-esterification with PEPCK and PDK4 being identified as key enzymes in this process. We have previously shown that glyceroneogenic enzymes such as PDK4 are rapidly induced in white adipose tissue during exercise. Recent studies have suggested that IL-6 regulates adipose tissue metabolism and gene expression during exercise. Interestingly, IL-6 has been reported to directly decrease PEPCK expression. The purpose of this investigation was to determine the role of IL-6 in modulating the effects of exercise on the expression of glyceroneogenic enzymes in mouse adipose tissue. We hypothesized that the exercise-mediated induction of PDK4 and PEPCK would be greater in adipose tissue from IL-6 deficient mice compared to wild type controls.
  
  
  RESULTS
  Treatment of cultured epididymal adipose tissue (eWAT) with IL-6 (150 ng/ml) increased the phosphorylation of AMPK, ACC and STAT3 and induced SOCS3 mRNA levels while decreasing PEPCK and PDK4 mRNA. AICAR decreased the expression of PDK4 and PEPCK. The activation of AMPK by IL-6 was independent of increases in lipolysis. An acute bout of treadmill running (15 meters/minute, 5% incline, 90 minutes) did not induce SOCS3 or increase phosphorylation of STAT3 in eWAT, indicating that IL-6 signalling was not activated. Exercise-induced increases in PEPCK and PDK4 mRNA expression were attenuated in eWAT from IL-6(-/-) mice in parallel with a greater relative increase in AMPK phosphorylation compared to exercised WT mice. These changes occurred independent of alterations in beta-adrenergic signalling in adipose tissue from IL-6(-/-) mice.
  
  
  CONCLUSIONS
  Our findings question the role of IL-6 signalling in adipose tissue during exercise and suggest an indirect effect of this cytokine in the regulation of adipose tissue gene expression during exercise.
authors: Department of Agriculture, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors: Zhongxiao
authors: Z
authors: Wan
authors: Ian
authors: I
authors: Ritchie
authors: Marie-Soleil
authors: MS
authors: Beaudoin
authors: Laura
authors: L
authors: Castellani
authors: Catherine B
authors: CB
authors: Chan
authors: David C
authors: DC
authors: Wright
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D004822:Epididymis / Q000166:cytology; D005989:Glycerides / Q000096:biosynthesis*; D005990:Glycerol / Q000378:metabolism*; D015850:Interleukin-6 / Q000172:deficiency / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D051379:Mice; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D010805:Physical Conditioning, Animal; D011494:Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D005989:Glycerides; D015850:Interleukin-6; D012333:RNA, Messenger; D011494:Protein Kinases; C403287:pyruvate dehydrogenase kinase 4; D055372:AMP-Activated Protein Kinases; D019764:Phosphoenolpyruvate Carboxykinase (ATP); D005990:Glycerol