Résumé :
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Communication n° 712. In the mouse embryo Pax3, which encodes a paired- and homeo-domain containing transcription factor, acts genetically upstream of the myogenic program and is essential for the determination of skeletal muscle progenitor cells. We have isolated and targeted the Pax3 gene with nlacZ and GFP reporters in order to examine the Pax3 expressing cell population more closely in mutant and heterozygote embryos as well as in the adult. Pax3 mutant embryos have no limb muscle and somite deficiencies, in addition to other defects, since Pax3 also plays an important role in the central nervous system and in neural crest derivatives. However, despite these important developmental functions, relevant Pax3 targets have not been identified. We have generated several alleles of Pax3, such as loss of function alleles, gain of function mutation (1), dominant negative mutation (F. R. and M. B., unpublished) and replacement of Pax3 by Pax7 (2). Using these alleles, we demonstrate that Pax3 is acting upstream of the FGF signaling pathway during myogenesis.
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