title: Site-specific differences of insulin action in adipose tissue derived from normal prepubertal children.
abstract: Body fat distribution determines obesity-related morbidity in adults but little is known of the aetiology or pathophysiology in children. This study investigates differences in insulin-mediated metabolism in primary cell cultures of subcutaneous and visceral preadipocytes derived from prepubertal children. The impact of differentiation and responses to TNFalpha exposure was also investigated. Proliferation rates were greater in subcutaneous versus visceral preadipocytes (41 h3 versus 69 h4; P=0.008). Insulin caused a dose-dependent increase in GSK-3 phosphorylation and an increase in MAPK phosphorylation over time, with increased sensitivity in subcutaneous preadipocytes. Post-differentiation, dose-dependent increases in GSK-3 phosphorylation were maintained, while MAPK phosphorylation was identical in both subtypes. No changes were observed in insulin receptor abundance pre-/post-differentiation. GLUT4 abundance was significantly increased in visceral versus subcutaneous adipocytes by 76(4)%; P=0.03), coincidental with increased insulin-stimulated 2-deoxy-glucose transport (+150(26)% versus +79(10)%; P=0.014) and further elevated by acute exposure to TNFalpha (+230(52)%; P=0.019 versus +123(24)%; P=0.025, respectively). TNFalpha also significantly increased basal glucose transport rates (+44(14)%; P=0.006 versus +34(11)%; P=0.007) and GLUT1 localisation to the plasma membrane. These data establish site-specific differences in subcutaneous and visceral fat cells from children. Responses to insulin varied with differentiation and TNFalpha exposure in the two depots, consistent with parallel changes in GLUT1/4 abundance and localisation.
authors.affiliation: Department of Surgery, University of Bristol, Bristol Royal Infirmary, Upper Maudlin Street, Bristol, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Grohmann
authors.forename: Claire
authors.initials: C
authors.lastname: Stewart
authors.forename: Gavin
authors.initials: G
authors.lastname: Welsh
authors.forename: Linda
authors.initials: L
authors.lastname: Hunt
authors.forename: Jeremy
authors.initials: J
authors.lastname: Tavaré
authors.forename: Jeff
authors.initials: J
authors.lastname: Holly
authors.forename: Julian
authors.initials: J
authors.lastname: Shield
authors.forename: Matt
authors.initials: M
authors.lastname: Sabin
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Crowne
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D038362:Glycogen Synthase Kinase 3 / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007223:Infant; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology; D010766:Phosphorylation / Q000187:drug effects; D012016:Reference Values; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D044465:White People
chemical_list: D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495677:SLC2A1 protein, human; C495692:SLC2A4 protein, human; D014409:Tumor Necrosis Factor-alpha; D038362:Glycogen Synthase Kinase 3; D005947:Glucose