Résumé :
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Growth and repair of adult skeletal muscle is achieved by a population of progenitor/stem cells, the satellite cells. Satellite cells are derived from a fetal population of Pax3-expressing progenitor cells providing successive waves of myogenic cells to sustain muscle growth during development We are interested in the identification of genes involved in the acquisition of stem-cell properties by the fetal progenitor when they progress into the post-natal satellite cell lineage. We took advantage of the Pax3GFP/+ mice, in which GFP labels the muscle progenitor cells (Relaix et al., 2005), to perform an expression profiling of muscle progenitor cells from early embryonic development to adulthood. RNAs of the FACS-sorted GFP-positive cells were subjected to a microarray analysis. By comparing different time points, it revealed the progressive modifications of the progenitor cell transcriptome over time. Strikingly, more than 3000 transcripts are regulated during the transition from primary to secondary myogenesis while about 1000 transcripts are regulated at later time points, suggesting that the adult muscle progenitor cells are molecularly defined at the fetal stage. In addition to the analysis and validation of the screen, we will present preliminary work on new factors which might be involved in satellite cells formation.
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