title: Induction of adiponectin gene expression in human myotubes by an adiponectin-containing HEK293 cell culture supernatant.
abstract: OBJECTIVE
  Adiponectin, an adipocytokine known to be down-regulated in obesity-linked disorders, is considered to be a potential key mediator of insulin sensitivity. In this study, we asked whether adiponectin is able to regulate ten selected genes possibly associated with insulin sensitivity in human skeletal muscle cells.
  
  
  METHODS
  To this end, we treated in vitro differentiated human myotubes with the culture supernatant of HEK293 cells stably transfected with human recombinant adiponectin and assessed gene expression by RT-PCR. Intracellular adiponectin protein was quantified by radioimmunoassay and visualized by Western blotting.
  
  
  RESULTS
  In contrast to the control supernatant, the adiponectin-containing supernatant consistently induced expression of adiponectin mRNA in human myotubes from eight different donors (mean increase: 90-fold over control; n=8, p<0.001). This increase in mRNA was paralleled by a rise in intracellular adiponectin protein (mean increase: 8.3-fold over control; n=4, p<0.05). Expression of the other nine candidate genes was not altered. In human skin fibroblasts and HepG2 cells, the adiponectin-enriched supernatant did not induce relevant amounts of adiponectin mRNA.
  
  
  CONCLUSIONS
  In conclusion, we show here that adiponectin gene expression is specifically inducible in skeletal muscle cells.
authors.affiliation: Department of Endocrinology, Metabolism, and Pathobiochemistry, Medical Clinic Tübingen, Eberhard-Karls-University, Otfried-Müller-Strasse 10, 72076 Tübingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Staiger
authors.forename: C
authors.initials: C
authors.lastname: Kausch
authors.forename: A
authors.initials: A
authors.lastname: Guirguis
authors.forename: M
authors.initials: M
authors.lastname: Weisser
authors.forename: E
authors.initials: E
authors.lastname: Maerker
authors.forename: M
authors.initials: M
authors.lastname: Stumvoll
authors.forename: R
authors.initials: R
authors.lastname: Lammers
authors.forename: F
authors.initials: F
authors.lastname: Machicao
authors.forename: H-U
authors.initials: HU
authors.lastname: Häring
mesh_terms: D052242:Adiponectin; D000328:Adult; D001706:Biopsy; D015992:Body Mass Index; D002460:Cell Line; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007668:Kidney; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology; D011506:Proteins / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
chemical_list: D052242:Adiponectin; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D012333:RNA, Messenger