title: Adipogenic progenitors from obese human skeletal muscle give rise to functional white adipocytes that contribute to insulin resistance.
abstract: OBJECTIVE
  Recent reports indicate that inter/intramuscular adipose tissue (IMAT), composed by adipocytes underneath the deep fascia of the muscles, is positively correlated with aging, obesity and insulin resistance in humans. However, no molecular/cellular evidence is available to support these interactions. The current study aimed to better characterize human skeletal muscle-derived adipogenic progenitors obtained from obese volunteers and investigate the impact of derived adipocytes on insulin action in primary skeletal muscle cells.
  
  
  METHODS
  Primary cultured stroma-vascular fraction (SVF) obtained from vastus lateralis muscle biopsies of middle-aged obese subjects was immunoseparated (magnetic beads or flow cytometry). The characteristics and/or metabolic phenotype of CD56(+), CD56(-) and CD56(-)CD15(+) cellular fractions were investigated by complementary approaches (flow cytometry, cytology, quantitative PCR and metabolic assays). The effects of conditioned media from CD56(-)CD15(+) cells differentiated into adipocytes on insulin action and signaling in human primary myotubes was also examined.
  
  
  RESULTS
  Our data indicate that CD56(+) and CD56(-) cellular fractions isolated from cultured SVF of human muscle contain two distinct committed progenitors: CD56(+) cells (that is, satellite cells) as myogenic progenitors and CD15(+) cells as adipogenic progenitors, respectively. CD56(-)CD15(+)-derived adipocytes display the phenotype and metabolic properties of white adipocytes. Secretions of CD56(-)CD15(+) cells differentiated into functional white adipocytes reduced insulin-mediated non-oxidative glucose disposal (P=0.0002) and insulin signaling.
  
  
  CONCLUSIONS
  Using in-vitro models, we show for the first time that secretions of skeletal muscle adipocytes are able to impair insulin action and signaling of muscle fibers. This paracrine effect could explain, at least in part, the negative association between high levels of IMAT and insulin sensitivity in obesity and aging.
authors.affiliation: INSERM UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France.|University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Laurens
authors.affiliation: INSERM UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France.|University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.
authors.forename: K
authors.initials: K
authors.lastname: Louche
authors.affiliation: UMR5273 UPS/CNRS/EFS/INSERM U1031, STROMALab, University de Toulouse, Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Sengenes
authors.affiliation: INSERM UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France.|University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.
authors.forename: M
authors.initials: M
authors.lastname: Coué
authors.affiliation: INSERM UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France.|University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.|Department of Clinical Biochemistry, Toulouse University Hospitals, Toulouse, France.
authors.forename: D
authors.initials: D
authors.lastname: Langin
authors.affiliation: INSERM UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France.|University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Moro
authors.affiliation: INSERM UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France.|University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.
authors.forename: V
authors.initials: V
authors.lastname: Bourlier
mesh_terms: D052438:Adipocytes, White / Q000378:metabolism*; D050156:Adipogenesis / Q000502:physiology; D019002:CD56 Antigen; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D005647:Fucosyltransferases; D006801:Humans; D007333:Insulin Resistance; D016256:Lewis X Antigen; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism; D009765:Obesity / Q000378:metabolism*
chemical_list: D019002:CD56 Antigen; D016256:Lewis X Antigen; C522918:NCAM1 protein, human; C066693:FUT4 protein, human; D005647:Fucosyltransferases