Circulating irisin levels and muscle FNDC5 mRNA expression are independent of IL-15 levels in mice.
Interleukin-15 (IL-15) and irisin are exercise-induced myokines that exert favorable effects on energy expenditure and metabolism. IL-15 can induce PGC-1α expression, which in turn induces expression of irisin and its precursor, FNDC5. Therefore, the present study tested the hypothesis that increases in circulating irisin levels and muscle FNDC5 mRNA expression are dependent on IL-15. Circulating irisin levels and gastrocnemius muscle FNDC5 mRNA expression were examined following acute exercise in control and IL-15-deleted (IL-15 KO) mice, following injection of IL-15 into IL-15 KO mice, and in transgenic mice with elevated circulating IL-15 levels (IL-15 Tg mice). Circulating IL-15 levels and muscle PGC-1α and PPARδ mRNA expressions were determined as positive controls. No effect of IL-15 deletion on post-exercise serum irisin levels or muscle FNDC5 mRNA expression was detected. While serum IL-15 levels and muscle PGC-1α expression were elevated post-exercise in control mice, both serum irisin levels and muscle FNDC5 expression decreased shortly after exercise in both control and IL-15 KO mice. A single injection of recombinant IL-15 into IL-15 KO mice that significantly increased muscle PPARδ and PGC-1α mRNA expressions had no effect on circulating irisin release, but modestly induced muscle FNDC5 expression. Additionally, serum irisin and gastrocnemius muscle FNDC5 expression in IL-15 Tg mice were similar to those of control mice. Muscle FNDC5 mRNA expression and irisin release are not IL-15-dependent in mice.
Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System, S-182 GRECC, 1660 S. Columbian Way, Seattle, WA, 98108, USA. quinnL@uw.edu.|Research Service, VA Puget Sound Health Care System, Seattle, WA, 98108, USA. quinnL@uw.edu.|Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, 98195, USA. quinnL@uw.edu.|Seattle Institute for Biomedical and Clinical Research, Seattle, WA, 98108, USA. quinnL@uw.edu.
LeBris S
LS
Quinn
Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System, S-182 GRECC, 1660 S. Columbian Way, Seattle, WA, 98108, USA.|Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, 98195, USA.
Barbara G
BG
Anderson
Seattle Institute for Biomedical and Clinical Research, Seattle, WA, 98108, USA.
Jennifer D
JD
Conner
Research Service, VA Puget Sound Health Care System, Seattle, WA, 98108, USA.
Tami
T
Wolden-Hanson
D000818:Animals; D005353:Fibronectins / Q000097:blood / Q000378:metabolism*; D019409:Interleukin-15 / Q000097:blood / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
C571428:FNDC5 protein, mouse; D005353:Fibronectins; D019409:Interleukin-15; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C091778:Ppard protein, mouse; C485290:Ppargc1a protein, mouse; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors
Cytokines; Exercise; Interleukin-15; Irisin; Muscle; Myokines