AP-1 Proteins Regulate Autophagy in Skeletal Muscle Progenitor Cells

Autophagy has been observed to be a key regulator in myogenesis, maintenance of quiescence in satellite cells (SC) and regenerative capacity of skeletal muscle. Activator protein-1 (AP-1) transcription factors have been proteins of interest in autophagy regulation in various cancers due to the established roles of AP-1 in cellular proliferation, death and survival. However, AP-1 involvement in the regulation autophagy in skeletal muscle progenitor cells has not been extensively assessed. AP-1 protein c-Jun is expressed in paired box gene 7 (Pax7) positive satellite cells. AP-1 proteins c-Jun and JunB regulate autophagy. Changes to c-Jun expression lead to changed autophagosome content in C2C12 cells in both growth conditions and induced autophagy conditions. Additionally, c-Jun knockdown altered autophagosome content in cultures containing Pax7+ and Pax7- cells. AP-1 protein c-Jun appeared to be regulated by mTor. AP-1 proteins act as autophagy regulators dependent on cell type and autophagy induction method.