In Vivo Gene Transfer of PPARγ Is Insufficient to Induce Adipogenesis in Skeletal Muscle

抄録

Skeletal muscle contains several progenitor/stem cells with myogenicity as well as adipogenicity such as satellite cells. Our previous study demonstrated that forced expression of PPARγ is sufficient to induce transdifferentiation of predetermined myoblasts in vitro. In the present study, we examined whether introduction of PPARγ gene could induce adipogenesis of satellite cells in vivo. A plasmid vector containing enhanced green fluorescent protein (EGFP) or PPARγ gene was introduced into rat tibialis anterior muscle by electroporation. Histological analyses revealed that electroporation induces degenerative/regenerative response in skeletal muscle, including activation of satellite cells. When EGFP gene was introduced, newly formed myotubes resulted from fusion of activated satellite cells, showed EGFP expression, indicating that electroporation could transfect satellite cells with exogenously introduced gene. Gene transfer of PPARγ resulted in an increase of PPARγ-positive mononucleated cells on day 3 after electroporation but failed to induce adipogenesis thereafter. These results suggested that, in addition to an expression of PPARγ, niches that support adipogenesis are required for satellite cells to enter adipogenesis in vivo.