Redefining the genetic hierarchies controlling skeletal myogenesis: Pax-3 and Myf-5 act upstream of MyoD.

Department of Molecular Biology, Centre National de la Recherche Scientifique, Unité de Recherche Associe 1947, Pasteur Institute, Paris, France.
Cell (Impact Factor: 33.12). 05/1997; 89(1):127-38. DOI: 10.1016/S0092-8674(00)80189-0
Source: PubMed

ABSTRACT We analyzed Pax-3 (splotch), Myf-5 (targeted with nlacZ), and splotch/Myf-5 homozygous mutant mice to investigate the roles that these genes play in programming skeletal myogenesis. In splotch and Myf-5 homozygous embryos, myogenic progenitor cell perturbations and early muscle defects are distinct. Remarkably, splotch/Myf-5 double homozygotes have a dramatic phenotype not seen in the individual mutants: body muscles are absent. MyoD does not rescue this double mutant phenotype since activation of this gene proves to be dependent on either Pax-3 or Myf-5. Therefore, Pax-3 and Myf-5 define two distinct myogenic pathways, and MyoD acts genetically downstream of these genes for myogenesis in the body. This genetic hierarchy does not appear to operate for head muscle formation.

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