Expression of beta-catenin in the developing chick myotome is regulated by myogenic signals

Maike Schmidt, Mikiko Tanaka, Andrea Munsterberg

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71 Citations (Scopus)
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The developmental signals that govern cell specification and differentiation in vertebrate somites are well understood. However, little is known about the downstream signalling pathways involved. We have shown previously that a combination of Shh protein and Wnt1 or Wnt3a-expressing fibroblasts is sufficient to activate skeletal muscle-specific gene expression in somite explants. Here, we have examined the molecular mechanisms by which the Wnt-mediated signal acts on myogenic precursor cells. We show that chick frizzled 1 (Fz1), β-catenin and Lef1 are expressed during somitogenesis. Lef1 and β-catenin transcripts become restricted to the developing myotome. Furthermore, β-catenin is expressed prior to the time at which MyoD transcripts can be detected. Expression of β-catenin mRNA is regulated by positive and negative signals derived from neural tube, notochord and lateral plate mesoderm. These signals include Bmp4, Shh and Wnt1/Wnt3a itself. In somite explants, Fz1, β-catenin and Lef1 are expressed prior to activation of myogenesis in response to Shh and Wnt signals. Thus, our data show that a combination of Shh and Wnt1 upregulates expression of Wnt pathway components in developing somites prior to myogenesis. Thus, Wnt1 could act through β-catenin on cells in the myotome.
Original languageEnglish
Pages (from-to)4105-4113
Number of pages9
Issue number19
Publication statusPublished - 2000

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