Redefining the Genetic Hierarchies Controlling Skeletal Myogenesis: Pax-3 and Myf-5 Act Upstream of MyoD

To evaluate the nature of these β-gal+ cells in the body, we examined saggital sections from E14.5 Sp/Myf-5a2−/− embryos that were stained for β-gal activity and hybridized with an antisense myogenin probe

Shahragim Tajbakhsh


Scholarcy highlights

  • During vertebrate embryogenesis, paraxial mesoderm flanking the neural tube becomes segmented into epithelial spheres called somites, which subsequently become compartmentalized into a dorsal epithelial dermomyotome and a ventral mesenchymal sclerotome
  • Myogenic progenitor cells in the dermomyotome give rise to all of the skeletal muscles of the body and some head muscles, while the remaining head muscles arise from more anterior nonsomitic paraxial and prechordal head mesoderm (reviewed by
  • From about embryonic day 10, muscle progenitor cells originating from the occipital somites undergo a long-range migration underneath the arches to constitute the hypoglossal muscles of the throat and some tongue musculature
  • We used a loss-of-function approach in mice to evaluate the respective roles that the paired box transcription factor Pax-3 and the bHLH myogenic regulatory factors Myf-5 and MyoD play in programming skeletal myogenesis
  • We demonstrate that muscle progenitor cells in the body require the combined actions of Pax-3 and Myf-5 to make muscle, while Pax-3 does not appear to play a role in establishing nonsomitic head muscles
  • Figure 7Model for the Genetic Hierarchies Operating in the Control of Skeletal Myogenesis
  • From our analysis of the Myf-5a2−/− null embryos, we have demonstrated that in the absence of this myogenic factor, muscle progenitor cells migrate aberrantly and fail to localize to the cental aspect of the somite

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