Modulating MyoD1 dosage activates alternate cell fate beyond myogenic differentiation [CUT&Run]

Increased TF dosage has been predicted to enhance expression of high-affinity target genes but also increase the binding of lower-affinity loci. The relative importance of high- versus lower-affinity TF binding in guiding cell fate decisions remains unclear.

To test the roles of TF dosage, we examined the effects of increasing the dosage of MyoD1, the “master regulator of myogenesis”, on skeletal muscle differentiation. Unexpectedly, increased MyoD1 dosage inhibited canonical myogenesis and redirected myoblast differentiation towards forming spontaneously contracting myotubes. This novel phenotype was driven by the MyoD1-dose-dependent upregulation of non-myogenic genes, including cell adhesion genes whose ectopic expression also inhibited classical myogenic differentiation and enabled myotube contraction.