Dlx5 and Dlx6 homeobox genes are required for specification of the mammalian vestibular apparatus.
The mammalian inner ear is a complex organ that develops from a surface ectoderm into distinct auditory and vestibular components. Congenital malformation of these two components resulting from single or multiple gene defects is a common clinical occurrence and is observed in patients with split hand/split foot malformation, a malformation which is phenocopied by Dlx5/6 null mice. Analysis of mice lacking Dlx5 and Dlx6 homeobox genes identified their restricted and combined expression in the otic epithelium as a crucial regulator of vestibular cell fates. Otic induction initiates without incident in Dlx5/6(-/-) embryos, but dorsal otic derivatives including the semicircular ducts, utricle, saccule, and endolymphatic duct fail to form. Dlx5 and Dlx6 seem to influence vestibular cell fates by restricting Pax2 and activating Gbx2 and Bmp4 expression domains. Given their proximity to the disease locus and the observed phenotype in Dlx5/6 null mice, Dlx5/6 are likely candidates to mediate the inner ear defects observed in patients with split hand/split foot malformation.
Robledo
Raymond F
RF
The Jackson Laboratory, Bar Harbor, Maine.
Lufkin
Thomas
T
D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D007758:Ear, Inner / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006720:Homozygote; D051379:Mice; D018345:Mice, Knockout; D051762:PAX2 Transcription Factor / Q000378:metabolism; D014722:Vestibule, Labyrinth / Q000196:embryology*; D001616:beta-Galactosidase / Q000378:metabolism
C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; C501120:Dlx5 protein, mouse; C100597:Dlx6 protein, mouse; C513182:Gbx2 protein, mouse; D018398:Homeodomain Proteins; D051762:PAX2 Transcription Factor; C497319:Pax2 protein, mouse; D001616:beta-Galactosidase