title: The Prx1 homeobox gene is critical for molar tooth morphogenesis.
abstract: The paired-related homeobox genes, Prx1 and Prx2, encode transcription factors critical for orofacial development. Prx1(-/-)/Prx2(-/-) neonates have mandibular hypoplasia and malformed mandibular incisors. Although the mandibular incisor phenotype has been briefly described (ten Berge et al., 1998, 2001; Lu et al., 1999), very little is known about the role of Prx proteins during tooth morphogenesis. Since the posterior mandibular region was relatively normal, we examined molar tooth development in Prx1(-/-)/Prx2(-/-) embryos to determine whether the tooth malformation is primary to the loss of Prx protein or secondary to defects in surrounding tissues. Three-dimensional (3D) morphological reconstructions demonstrated that Prx1(-/-)/Prx2(-/-) embryos had molar malformations, including cuspal changes and ectopic epithelial projections. Although we demonstrate that Prx1 protein is expressed only mesenchymally, 3D reconstructions showed important morphological defects in epithelial tissues at the cap and bell stages. Analysis of these data suggests that the Prx homeoproteins are critical for mesenchymal-epithelial signaling during tooth morphogenesis.
authors.affiliation: Department of Cell Biology and Anatomy, Suite 601, Medical University of South Carolina, 171 Ashley Avenue, Charleston, NC 29435, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Mitchell
authors.forename: D M
authors.initials: DM
authors.lastname: Hicklin
authors.forename: P M
authors.initials: PM
authors.lastname: Doughty
authors.forename: J H
authors.initials: JH
authors.lastname: Hicklin
authors.forename: J W
authors.initials: JW
authors.lastname: Dickert
authors.forename: S M
authors.initials: SM
authors.lastname: Tolbert
authors.forename: R
authors.initials: R
authors.lastname: Peterkova
authors.forename: M J
authors.initials: MJ
authors.lastname: Kern
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D021621:Imaging, Three-Dimensional; D008334:Mandible / Q000002:abnormalities / Q000196:embryology* / Q000378:metabolism; D008437:Maxilla / Q000002:abnormalities / Q000196:embryology* / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008963:Molar / Q000002:abnormalities / Q000196:embryology* / Q000378:metabolism; D009024:Morphogenesis / Q000235:genetics / Q000502:physiology; D020033:Protein Isoforms; D014071:Tooth Abnormalities / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D020033:Protein Isoforms; C489936:Prrx1 protein, mouse; C115469:Prrx2 protein, mouse