Activation of myogenesis by the homeobox gene Lbx1 requires cell proliferation.
Myogenic differentiation can be initiated by a limited number of molecules. In this work, we analyzed the function of the homeobox gene Lbx1 in chicken embryos and explant cultures. We demonstrate that overexpression of Lbx1 in vivo and in vitro leads to a strong activation of various muscle markers. We show that cell proliferation, which is strongly stimulated by Lbx1 and Pax3, is required for Lbx1- or Pax3-dependent myogenic activation. Inhibition of cell proliferation prevents expression of muscle differentiation markers, while the activation of other putative downstream targets of Pax3 and Lbx1 is not affected. Our findings imply that a critical function of Pax3 and Lbx1 during muscle cell formation is the enlargement of muscle cell populations. The growth of the muscle precursor cell population may increase the bias for myogenic differentiation and thus enable myogenic cells to respond to environmental cues.
Mennerich
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Institute of Physiological Chemistry, Martin-Luther-University Halle, Hollystrasse 1, D-06097 Halle, Germany.
Braun
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T
D000818:Animals; D030161:Avian Proteins; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000235:genetics; D005801:Genes, Homeobox; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D009124:Muscle Proteins / Q000235:genetics*; D009132:Muscles / Q000737:chemistry*; D017570:MyoD Protein / Q000235:genetics; D018008:Myogenin / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors
D030161:Avian Proteins; C485734:DACH2 protein, Gallus gallus; D004268:DNA-Binding Proteins; C485735:Dach2 protein, mouse; C113279:LBX1 protein, Gallus gallus; C491868:Lbx1h protein, mouse; D009124:Muscle Proteins; D017570:MyoD Protein; D018008:Myogenin; D009687:Nuclear Proteins; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; C068686:Pax3 protein, mouse