title: Abnormal epigenetic changes during differentiation of human skeletal muscle stem cells from obese subjects.
abstract: Human skeletal muscle stem cells are important for muscle regeneration. However, the combined genome-wide DNA methylation and expression changes taking place during adult myogenesis have not been described in detail and novel myogenic factors may be discovered. Additionally, obesity is associated with low relative muscle mass and diminished metabolism. Epigenetic alterations taking place during myogenesis might contribute to these defects.
  
  
  
  We used Infinium HumanMethylation450 BeadChip Kit (Illumina) and HumanHT-12 Expression BeadChip (Illumina) to analyze genome-wide DNA methylation and transcription before versus after differentiation of primary human myoblasts from 14 non-obese and 14 obese individuals. Functional follow-up experiments were performed using siRNA mediated gene silencing in primary human myoblasts and a transgenic mouse model.
  
  
  
  We observed genome-wide changes in DNA methylation and expression patterns during differentiation of primary human muscle stem cells (myoblasts). We identified epigenetic and transcriptional changes of myogenic transcription factors (MYOD1, MYOG, MYF5, MYF6, PAX7, MEF2A, MEF2C, and MEF2D), cell cycle regulators, metabolic enzymes and genes previously not linked to myogenesis, including IL32, metallothioneins, and pregnancy-specific beta-1-glycoproteins. Functional studies demonstrated IL-32 as a novel target that regulates human myogenesis, insulin sensitivity and ATP levels in muscle cells. Furthermore, IL32 transgenic mice had reduced insulin response and muscle weight. Remarkably, approximately 3.7 times more methylation changes (147,161 versus 39,572) were observed during differentiation of myoblasts from obese versus non-obese subjects. In accordance, DNMT1 expression increased during myogenesis only in obese subjects. Interestingly, numerous genes implicated in metabolic diseases and epigenetic regulation showed differential methylation and expression during differentiation only in obese subjects.
  
  
  
  Our study identifies IL-32 as a novel myogenic regulator, provides a comprehensive map of the dynamic epigenome during differentiation of human muscle stem cells and reveals abnormal epigenetic changes in obesity.
authors.affiliation: Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden.
authors.forename: Cajsa
authors.identifier: 0000-0003-1124-7570
authors.initials: C
authors.lastname: Davegårdh
authors.affiliation: Department of Endocrinology, Rigshospitalet, Copenhagen, 2100, Denmark.
authors.forename: Christa
authors.initials: C
authors.lastname: Broholm
authors.affiliation: Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden.
authors.forename: Alexander
authors.initials: A
authors.lastname: Perfilyev
authors.affiliation: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Tora
authors.initials: T
authors.lastname: Henriksen
authors.affiliation: Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden.
authors.forename: Sonia
authors.initials: S
authors.lastname: García-Calzón
authors.affiliation: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lone
authors.initials: L
authors.lastname: Peijs
authors.affiliation: Department of Endocrinology, Rigshospitalet, Copenhagen, 2100, Denmark.
authors.forename: Ninna Schiøler
authors.initials: NS
authors.lastname: Hansen
authors.affiliation: Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden.
authors.forename: Petr
authors.initials: P
authors.lastname: Volkov
authors.affiliation: Department of Exercise and Sports Sciences, Faculty of Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Kjøbsted
authors.affiliation: Department of Exercise and Sports Sciences, Faculty of Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jørgen F P
authors.initials: JF
authors.lastname: Wojtaszewski
authors.affiliation: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Maria
authors.initials: M
authors.lastname: Pedersen
authors.affiliation: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
authors.affiliation: Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, 80309, USA.|Department of Medicine, University of Colorado, Aurora, CO, 80045, USA.
authors.forename: Dov B
authors.initials: DB
authors.lastname: Ballak
authors.affiliation: Department of Medicine, University of Colorado, Aurora, CO, 80045, USA.|Department of Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Dinarello
authors.affiliation: Department of Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Heinhuis
authors.affiliation: Department of Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Leo A B
authors.initials: LA
authors.lastname: Joosten
authors.affiliation: Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden.
authors.forename: Emma
authors.initials: E
authors.lastname: Nilsson
authors.affiliation: Department of Endocrinology, Rigshospitalet, Copenhagen, 2100, Denmark.|Early Clinical Development, Translational Medical Unit, AstraZeneca, Mölndal, 431 83, Sweden.
authors.forename: Allan
authors.initials: A
authors.lastname: Vaag
authors.affiliation: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.|Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Camilla
authors.initials: C
authors.lastname: Scheele
authors.affiliation: Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden. charlotte.ling@med.lu.se.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Ling
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D006801:Humans; D051379:Mice; D008875:Middle Aged; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000473:pathology / Q000502:physiology*; D009765:Obesity / Q000235:genetics* / Q000473:pathology*; D013234:Stem Cells / Q000473:pathology / Q000502:physiology*
keywords: ARPP21; CGB; DNA methylation; Epigenetics; IL-32; Insulin resistance; MT; Myogenesis; Obesity; PSG; TGF-β3