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Properties of branchiomeric and somite‐derived muscle development in Tbx1 mutant embryos
Author(s) -
Grifone Raphälle,
Jarry Thérèse,
Dandonneau Mathieu,
Grenier Julien,
Duprez Delphine,
Kelly Robert G.
Publication year - 2008
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/dvdy.21718
Subject(s) - tbx1 , biology , myogenesis , craniofacial , mesoderm , microbiology and biotechnology , anatomy , myocyte , genetics , embryonic stem cell , gene , gene expression , promoter
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.