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 ☆

摘要

TheDlxhomeoboxgenefamilyisexpressedinacomplexpatternwithintheembryoniccraniofacialectodermandectomesenchyme.ApreviousstudyestablishedthatDlx-2isessentialfordevelopmentofproximalregionsofthemurinefirstandsecondbranchialarches.HerewedescribethecraniofacialphenotypeofmicewithmutationsinDlx-1andDlx-1and-2.TheskeletalandsofttissueanalysesofmicewithDlx-1andDlx-1and-2mutationsprovideadditionalevidencethattheDlxgenesregulateproximodistalpatterningofthebranchialarches.ThisanalysisalsoelucidatesdistinctandoverlappingrolesforDlx-1andDlx-2incraniofacialdevelopment.Furthermore,micelackingbothDlx-1and-2haveuniqueabnormalities,includingtheabsenceofmaxillarymolars.Dlx-1and-2areexpressedintheproximalanddistalfirstandsecondarches,yetonlytheproximalregionsareabnormal.ThenestedexpressionpatternsofDlx-1,-2,-3,-5,and-6provideevidenceforamodelthatpredictstheregion-specificrequirementsforeachgene.Finally,theDlx-2andDlx-1and-2mutantshaveectopicskullcomponentsthatresemblebonesandcartilagesfoundinphylogeneticallymoreprimitivevertebrates./p/div