New insight into MyoD regulation: involvement in rhabdomyosarcoma pathway?

The transcription factor MyoD, member of the myogenic regulators family, in duced differentiation in precursor cells by its ability to arrest cell prol iferation and to activate muscle specific genes. MyoD plays a key role in t he antagonism between proliferation and to activate muscle specific genes. MyoD plays a key role in the antagonism between proliferation and different iation. The withdrawal from the cell cycle and the activation of muscle dif ferentiation are related to the level of MyoD protein. The cyclin E-cdk2 co mplex, one of the key regulators of the G1/S transition is directly implica ted in the degradation of MyoD by the ubiquitin-proteasome pathway, leading the myoblasts to proliferate. The display of this control in normal myobla sts suggest that its deficiency in the muscle stem cells could lead to the formation of rhabdomyosarcomas which have lost both the control of cell pro liferation and the transcriptional activity of MyoD.