Fig. 1.

Role of adiponectin in skeletal muscle regeneration. Beyond its metabolic role, gAd exerts a significant function as a regenerating hormone in skeletal muscle. Skeletal muscle represents an autocrine circuit of fAd production, the amount of which is further increased when an injury occurs. Indeed, damage develops an inflammatory environment that leads to adiponectin production via two different mechanisms: (1) secretion of IL-6 and IFN-γ, which induces the up-regulation of adiponectin expression by skeletal muscle; (2) recruitment of activated macrophages secreting fAd that, in turn, is cleaved into gAd. gAd plays a major role in skeletal muscle regeneration, acting on different cell populations involved in tissue regeneration. gAd acts on satellite cells by inducing their activation and migration towards the damaged muscle site. gAd also acts as a chemo-attractant factor for mesoangioblasts, non-resident muscle progenitor cells, recruited to the injured region. Here, gAd promotes myogenesis of both satellite cells and mesoangioblasts, thus concurring to rebuild the damaged fibers