title: Interleukin-15 stimulates adiponectin secretion by 3T3-L1 adipocytes: evidence for a skeletal muscle-to-fat signaling pathway.
abstract: Interleukin-15 (IL-15) is a cytokine which is highly expressed in skeletal muscle tissue, and which has anabolic effects on skeletal muscle protein dynamics both in vivo and in vitro. Additionally, administration of IL-15 to rats and mice inhibits white adipose tissue deposition. To determine if the action of IL-15 on adipose tissue is direct, the capacity of cultured murine 3T3-L1 preadipocytes and adipocytes to respond to IL-15 was examined. IL-15 administration inhibited lipid accumulation in differentiating 3T3-L1 preadipocytes, and stimulated secretion of the adipocyte-specific hormone adiponectin by differentiated 3T3-L1 adipocytes. The latter observation constitutes the first report of a cytokine or growth factor which stimulates adiponectin production. IL-15 mRNA expression by cultured 3T3-L1 adipogenic cells and C2C12 murine skeletal myogenic cells was also examined. Quantitative real-time PCR indicated IL-15 mRNA was expressed by C2C12 skeletal myogenic cells, and was upregulated more than 10-fold in differentiated skeletal myotubes compared to undifferentiated myoblasts. In contrast, 3T3-L1 cells expressed little or no IL-15 mRNA at either the undifferentiated preadipocyte or differentiated adipocyte stages. These findings provide support for the hypothesis that IL-15 functions in a muscle-to-fat endocrine axis which modulates fat:lean body composition and insulin sensitivity.
authors.affiliation: Geriatric Research, Education, and Clinical Center, 151 American Lake Division, VA Puget Sound Health Care System, Tacoma, WA 98493, USA. quinnl@u.washington.edu
authors.forename: Lebris S
authors.initials: LS
authors.lastname: Quinn
authors.forename: Lena
authors.initials: L
authors.lastname: Strait-Bodey
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Anderson
authors.forename: Josep M
authors.initials: JM
authors.lastname: Argilés
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Havel
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D052242:Adiponectin / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D019409:Interleukin-15 / Q000494:pharmacology*; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D052242:Adiponectin; D019409:Interleukin-15