PPARdelta mediates IL15 metabolic actions in myotubes: effects of hyperthermia.

C2C12 cells exposed to hyperthermia (41 degrees C) experienced an increase in both protein synthesis and degradation. The addition of IL15 under hyperthermic conditions resulted in an important increase in protein synthesis with no changes in protein degradation, except when cells overexpressed PPARdelta. The PPARdelta agonist GW501516 exerted similar effects on protein synthesis to IL15. Expression of a mutant dominant negative form of PPARdelta prevented the effect of the cytokine on protein synthesis, suggesting that this transcription factor is involved in the anabolic action of IL15. The present study also suggests that the effects of IL15 on lipid oxidation could be mediated by PPARdelta.