Properties of branchiomeric and somite-derived muscle development in Tbx1 mutant embryos

Authors

  • Raphälle Grifone,

    1. Inserm Avenir group, Developmental Biology Institute of Marseilles-Luminy, UMR CNRS 6216 Université de la Méditerranée, Campus de Luminy, Marseille, France
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  • Thérèse Jarry,

    1. Inserm Avenir group, Developmental Biology Institute of Marseilles-Luminy, UMR CNRS 6216 Université de la Méditerranée, Campus de Luminy, Marseille, France
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  • Mathieu Dandonneau,

    1. Inserm Avenir group, Developmental Biology Institute of Marseilles-Luminy, UMR CNRS 6216 Université de la Méditerranée, Campus de Luminy, Marseille, France
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  • Julien Grenier,

    1. UMR CNRS 7622, Université Pierre et Marie Curie, Campus de Jussieu, Paris, France
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  • Delphine Duprez,

    1. UMR CNRS 7622, Université Pierre et Marie Curie, Campus de Jussieu, Paris, France
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  • Robert G. Kelly

    Corresponding author
    1. Inserm Avenir group, Developmental Biology Institute of Marseilles-Luminy, UMR CNRS 6216 Université de la Méditerranée, Campus de Luminy, Marseille, France
    • Inserm Avenir group, Developmental Biology Institute of Marseilles-Luminy, UMR CNRS 6216 Université de la Méditerranée, Campus de Luminy, Case 907, 13288 Marseille Cedex 9 France
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Abstract

Vertebrate craniofacial and trunk myogenesis are regulated by distinct genetic programs. Tbx1, homologue of the del22q11.2 syndrome candidate gene TBX1, controls branchiomeric craniofacial muscle development. Here, we demonstrate using immunohistochemistry that myogenic regulatory factors are activated in Tbx1-positive cells within pharyngeal mesoderm. These cells are also Islet1 and Capsulin-positive and in the absence of Tbx1 persist in the core of the first arch. Sporadic hypoplastic mandibular muscles in Tbx1−/− embryos contain Pax7-positive myocytes with indistinguishable differentiation properties from wild-type muscles and have normal tendon attachments and fiber-type patterning. In contrast to TBX1 haploinsufficient del22q11.2 syndrome patients, no alteration in fiber-type distribution was detected in Tbx1+/− adult masseter and pharyngeal constrictor muscles. Furthermore, Tbx1-expressing limb muscles display normal patterning, differentiation, fiber-type growth, fiber-type distribution and fetal maturation in the absence of Tbx1. The critical requirement for Tbx1 during muscle development is thus in the robust onset of myogenic specification in pharyngeal mesoderm. Developmental Dynamics 237:3071–3078, 2008. © 2008 Wiley-Liss, Inc.

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