title: Abnormalities of AMPK activation and glucose uptake in cultured skeletal muscle cells from individuals with chronic fatigue syndrome.
abstract: BACKGROUND
  Post exertional muscle fatigue is a key feature in Chronic Fatigue Syndrome (CFS). Abnormalities of skeletal muscle function have been identified in some but not all patients with CFS. To try to limit potential confounders that might contribute to this clinical heterogeneity, we developed a novel in vitro system that allows comparison of AMP kinase (AMPK) activation and metabolic responses to exercise in cultured skeletal muscle cells from CFS patients and control subjects.
  
  
  METHODS
  Skeletal muscle cell cultures were established from 10 subjects with CFS and 7 age-matched controls, subjected to electrical pulse stimulation (EPS) for up to 24h and examined for changes associated with exercise.
  
  
  RESULTS
  In the basal state, CFS cultures showed increased myogenin expression but decreased IL6 secretion during differentiation compared with control cultures. Control cultures subjected to 16 h EPS showed a significant increase in both AMPK phosphorylation and glucose uptake compared with unstimulated cells. In contrast, CFS cultures showed no increase in AMPK phosphorylation or glucose uptake after 16 h EPS. However, glucose uptake remained responsive to insulin in the CFS cells pointing to an exercise-related defect. IL6 secretion in response to EPS was significantly reduced in CFS compared with control cultures at all time points measured.
  
  
  CONCLUSIONS
  EPS is an effective model for eliciting muscle contraction and the metabolic changes associated with exercise in cultured skeletal muscle cells. We found four main differences in cultured skeletal muscle cells from subjects with CFS; increased myogenin expression in the basal state, impaired activation of AMPK, impaired stimulation of glucose uptake and diminished release of IL6. The retention of these differences in cultured muscle cells from CFS subjects points to a genetic/epigenetic mechanism, and provides a system to identify novel therapeutic targets.
authors.affiliation: Institute of Cellular Medicine, William Leech Building, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Audrey E
authors.initials: AE
authors.lastname: Brown
authors.affiliation: Institute of Cellular Medicine, William Leech Building, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom; Newcastle Hospitals, NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.
authors.forename: David E
authors.initials: DE
authors.lastname: Jones
authors.affiliation: Institute of Cellular Medicine, William Leech Building, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom; Newcastle Hospitals, NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Walker
authors.affiliation: Newcastle Hospitals, NHS Foundation Trust, Newcastle upon Tyne, United Kingdom; Institute for Ageing and Health, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Julia L
authors.initials: JL
authors.lastname: Newton
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000704:Analysis of Variance; D015153:Blotting, Western; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D004558:Electric Stimulation; D004789:Enzyme Activation / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise / Q000502:physiology*; D015673:Fatigue Syndrome, Chronic / Q000378:metabolism / Q000503:physiopathology*; D005947:Glucose / Q000493:pharmacokinetics*; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D018008:Myogenin / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D015850:Interleukin-6; D018008:Myogenin; D007770:L-Lactate Dehydrogenase; D055372:AMP-Activated Protein Kinases; D005947:Glucose
references.citation: Cell Tissue Res. 1992 Oct;270(1):189-98
references.pmid: 1423520
references.citation: Ann Intern Med. 1994 Dec 15;121(12):953-9
references.pmid: 7978722
references.citation: Biomaterials. 2014 Nov;35(35):9438-46
references.pmid: 25154662
references.citation: Proc Natl Acad Sci U S A. 2014 Apr 15;111(15):5508-13
references.pmid: 24706792
references.citation: Biotechnol Lett. 2014 May;36(5):1113-24
references.pmid: 24563297
references.citation: Biomaterials. 2013 Jul;34(23):5759-65
references.pmid: 23643182
references.citation: Am J Physiol Cell Physiol. 2013 Jan 15;304(2):C128-36
references.pmid: 23114963
references.citation: Aging Cell. 2012 Dec;11(6):986-95
references.pmid: 22882433
references.citation: PLoS One. 2012;7(3):e33203
references.pmid: 22457744
references.citation: Diabetologia. 2012 Apr;55(4):1128-39
references.pmid: 22282161
references.citation: Eur J Clin Invest. 2012 Feb;42(2):186-94
references.pmid: 21749371
references.citation: Lancet. 2011 Mar 5;377(9768):823-36
references.pmid: 21334061
references.citation: PLoS One. 2010;5(10):e13535
references.pmid: 21042574
references.citation: J Appl Physiol (1985). 2010 Sep;109(3):840-8
references.pmid: 20634357
references.citation: Scand J Med Sci Sports. 2010 Apr;20(2):282-90
references.pmid: 19422646
references.citation: J Intern Med. 2010 Apr;267(4):394-401
references.pmid: 20433583
references.citation: Am J Physiol Regul Integr Comp Physiol. 2009 Dec;297(6):R1724-32
references.pmid: 19812359
references.citation: Proc Natl Acad Sci U S A. 1981 Sep;78(9):5623-7
references.pmid: 6946499
references.citation: J Biol. 2003;2(4):28
references.pmid: 14511394
references.citation: Biochem Biophys Res Commun. 2004 Jul 23;320(2):449-54
references.pmid: 15219849
references.citation: Mol Biol Cell. 2004 Apr;15(4):2013-26
references.pmid: 14767066
references.citation: Am J Physiol. 1996 Feb;270(2 Pt 1):E299-304
references.pmid: 8779952
references.citation: J Cell Biol. 1999 May 3;145(3):633-42
references.pmid: 10225962
references.citation: J Appl Physiol (1985). 2005 Feb;98(2):706-13
references.pmid: 15475606
references.citation: Cell Metab. 2005 Jul;2(1):9-19
references.pmid: 16054095
references.citation: Semin Cell Dev Biol. 2005 Aug-Oct;16(4-5):585-95
references.pmid: 16099183
references.citation: Exp Cell Res. 2007 May 15;313(9):1853-65
references.pmid: 17425954
references.citation: J Cell Biol. 2007 Jun 4;177(5):769-79
references.pmid: 17548510
references.citation: Cell Metab. 2008 Jan;7(1):33-44
references.pmid: 18177723
references.citation: Growth Factors. 2008 Apr;26(2):61-73
references.pmid: 18428025
references.citation: Clin Gastroenterol Hepatol. 2008 Sep;6(9):1041-8
references.pmid: 18691944
references.citation: Am J Physiol Endocrinol Metab. 2008 Nov;295(5):E1191-204
references.pmid: 18780777
references.citation: Endocrinology. 2009 Feb;150(2):600-6
references.pmid: 18818284
references.citation: Biochem J. 2009 Mar 1;418(2):261-75
references.pmid: 19196246
references.citation: Diabetes. 2009 Sep;58(9):1953-60
references.pmid: 19502419
references.citation: J Allergy Clin Immunol. 2003 Aug;112(2):397-403
references.pmid: 12897748
references.citation: J Appl Physiol (1985). 2003 Dec;95(6):2273-7
references.pmid: 12937023