Role of the Dlx homeobox genes in proximodistal patterning of the branchial arches: mutations of Dlx-1, Dlx-2, and Dlx-1 and -2 alter morphogenesis of proximal skeletal and soft tissue structures derived from the first and second arches.
The Dlx homeobox gene family is expressed in a complex pattern within the embryonic craniofacial ectoderm and ectomesenchyme. A previous study established that Dlx-2 is essential for development of proximal regions of the murine first and second branchial arches. Here we describe the craniofacial phenotype of mice with mutations in Dlx-1 and Dlx-1 and -2. The skeletal and soft tissue analyses of mice with Dlx-1 and Dlx-1 and -2 mutations provide additional evidence that the Dlx genes regulate proximodistal patterning of the branchial arches. This analysis also elucidates distinct and overlapping roles for Dlx-1 and Dlx-2 in craniofacial development. Furthermore, mice lacking both Dlx-1 and -2 have unique abnormalities, including the absence of maxillary molars. Dlx-1 and -2 are expressed in the proximal and distal first and second arches, yet only the proximal regions are abnormal. The nested expression patterns of Dlx-1, -2, -3, -5, and -6 provide evidence for a model that predicts the region-specific requirements for each gene. Finally, the Dlx-2 and Dlx-1 and -2 mutants have ectopic skull components that resemble bones and cartilages found in phylogenetically more primitive vertebrates.
Qiu
M
M
Center for Neurobiology and Psychiatry, Department of Psychiatry, University of California at San Francisco, 94143-0984, USA.
Bulfone
A
A
Ghattas
I
I
Meneses
J J
JJ
Christensen
L
L
Sharpe
P T
PT
Presley
R
R
Pedersen
R A
RA
Rubenstein
J L
JL
D000818:Animals; D001934:Branchial Region / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D019465:Craniofacial Abnormalities / Q000235:genetics / Q000473:pathology; D003598:Cytoskeletal Proteins; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008817:Mice, Mutant Strains; D009024:Morphogenesis / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D016601:RNA-Binding Proteins; D014157:Transcription Factors
D003598:Cytoskeletal Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; D016601:RNA-Binding Proteins; C093661:Tes protein, mouse; D014157:Transcription Factors