Muscle stem cells are muscle precursor cells that reside between sarcolemma and basal lamina of muscle fibers in adult skeletal muscle. Adult muscle stem cells are maintained in a quiescent state. Upon Injury, they have the ability to proliferate and differentiate into multinucleated muscle fibers to regenerate muscle. We observed that Myod pre-mRNA is accumulated in quiescent satellite cells. We found out that DEK protein, the target of microRNA-489 in quiescent satellite cells to maintain quiescence, is involved in Myod pre-mRNA intron removal during satellite cell activation. Moreover, DEK serine 20 and 33 phosphorylation is found to be important for DEK splicing activity in mice. The early expression of MyoD protein during early activation of satellite cells might be essential to...[ Read more ]

Muscle stem cells are muscle precursor cells that reside between sarcolemma and basal lamina of muscle fibers in adult skeletal muscle. Adult muscle stem cells are maintained in a quiescent state. Upon Injury, they have the ability to proliferate and differentiate into multinucleated muscle fibers to regenerate muscle. We observed that Myod pre-mRNA is accumulated in quiescent satellite cells. We found out that DEK protein, the target of microRNA-489 in quiescent satellite cells to maintain quiescence, is involved in Myod pre-mRNA intron removal during satellite cell activation. Moreover, DEK serine 20 and 33 phosphorylation is found to be important for DEK splicing activity in mice. The early expression of MyoD protein during early activation of satellite cells might be essential to satellite cells activation and muscle regeneration process. The rapid and efficient activation of satellite cells in response to injury might be achieved by rapid MyoD protein expression through splicing pre-accumulated pre-mRNA in the quiescent satellite cells by DEK.