Author:
Ajuwon Kolapo M.,Spurlock Michael E.
Abstract
We recently provided evidence that interleukin-15 (IL-15) is expressed lowly in the pig adipocyte and that interferon-γ (IFN-γ) markedly increases this expression through a pathway regulated in part by protein kinase C (Ajuwon KM, Jacobi SK, Kuske JL, and Spurlock ME. Am J Physiol Regul Integr Comp Physiol 286: R547–R553, 2004). In the present study, we tested the hypothesis that IL-15 acts directly on the adipocyte to regulate lipid accretion by enhancing lipolysis or suppressing lipogenesis. Using recombinant porcine IL-15, we determined that this cytokine stimulates lipolysis in a dose-dependent manner ( P < 0.001). Furthermore, comparative studies with other cytokines showed that IL-15 is more potent in its acute stimulation of lipolysis than either TNF-α, IL-6, or LPS ( P < 0.001). When specific inhibitors of protein kinase A or Janus kinase are present, the lipolytic effect of IL-15 is attenuated ( P < 0.01). These data indicate that, in addition to its regulation of muscle protein accretion and T-cell growth and development, IL-15 also targets the adipocyte directly to alter stimulate lipolysis. Thus, when induced by IFN-γ or other inflammatory mediators, IL-15 may be a significant homeorhetic factor that mobilizes and directs energy away from the adipocyte to other cells during the acute phase of the inflammatory response.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
45 articles.
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