title: Human skeletal muscle cell differentiation is associated with changes in myogenic markers and enhanced insulin-mediated MAPK and PKB phosphorylation.
abstract: OBJECTIVE
  We hypothesized that myogenic differentiation of HSMC would yield a more insulin responsive phenotype.
  
  
  METHODS
  We assessed expression of several proteins involved in insulin action or myogenesis during differentiation of primary human skeletal muscle cultures (HSMC).
  
  
  RESULTS
  Differentiation increased creatine kinase activity and expression of desmin and myocyte enhancer factor (MEF)2C. No change in expression was observed for big mitogen-activated protein kinase (BMK1/ERK5), MEF2A, insulin receptor (IR), hexokinase II, and IR substrates 1 and 2, while expression of glycogen synthase, extracellular signal-regulated kinase 1 and 2 (ERK1/2 MAP kinase) and the insulin responsive aminopeptidase increased after differentiation. In contrast to protein kinase B (PKB)a, expression of (PKB)b increased, with differentiation. Both basal and insulin-stimulated PI 3-kinase activity increased with differentiation. Insulin-mediated phosphorylation of PKB and ERK1/2 MAP kinase increased after differentiation.
  
  
  CONCLUSIONS
  Components of the insulin-signalling machinery are expressed in myoblast and myotube HSMC; however, insulin responsiveness to PKB and ERK MAP kinase phosphorylation increases with differentiation.
authors.affiliation: Department of Surgical Science, Karolinska Institutet, Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Al-Khalili
authors.forename: D
authors.initials: D
authors.lastname: Krämer
authors.forename: P
authors.initials: P
authors.lastname: Wretenberg
authors.forename: A
authors.initials: A
authors.lastname: Krook
mesh_terms: D015415:Biomarkers / Q000032:analysis; D015153:Blotting, Western / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D003402:Creatine Kinase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis; D003893:Desmin / Q000032:analysis; D005260:Female; D006593:Hexokinase / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000378:metabolism; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; D008297:Male; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D018006:Myogenic Regulatory Factors / Q000032:analysis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin / Q000032:analysis; D014157:Transcription Factors / Q000032:analysis
chemical_list: D015415:Biomarkers; D003402:Creatine Kinase; D004268:DNA-Binding Proteins; D003893:Desmin; D006593:Hexokinase; D007328:Insulin; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; D020928:Mitogen-Activated Protein Kinases; D018006:Myogenic Regulatory Factors; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin; D014157:Transcription Factors; C578035:MEF2A protein, human; C578040:MEF2C protein, human