Sonic hedgehog signalling inhibits palatogenesis and arrests tooth development in a mouse model of the nevoid basal cell carcinoma syndrome.
Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant or spontaneous disorder characterized by multiple cutaneous basal cell carcinomas, odontogenic keratocysts, skeletal anomalies and facial dysmorphology, including cleft lip and palate. Causative mutations for NBCCS occur in the PTCH1 gene on chromosome 9q22.3-q31, which encodes the principle receptor for the Hedgehog signalling pathway. We have investigated the molecular basis of craniofacial defects seen in NBCCS using a transgenic mouse model expressing Shh in basal epithelium under a Keratin-14 promoter. These mice have an absence of flat bones within the skull vault, hypertelorism, open-bite malocclusion, cleft palate and arrested tooth development. Significantly, increased Hedgehog signal transduction in these mice can influence cell fate within the craniofacial region. In medial edge epithelium of the palate, Shh activity prevents apoptosis and subsequent palatal shelf fusion. In contrast, high levels of Shh in odontogenic epithelium arrests tooth development at the bud stage, secondary to a lack of cell proliferation in this region. These findings illustrate the importance of appropriately regulated Hedgehog signalling during early craniofacial development and demonstrate that oro-facial clefting and hypodontia seen in NBCCS can occur as a direct consequence of increased Shh signal activity within embryonic epithelial tissues.
Cobourne
Martyn T
MT
Department of Craniofacial Development and Orthodontics, Dental Institute, King's College London, Floor 27, Guy's Hospital, London SE1 9RT, UK. martyn.cobourne@kcl.ac.uk
Xavier
Guilherme M
GM
Depew
Michael
M
Hagan
Louise
L
Sealby
Jane
J
Webster
Zoe
Z
Sharpe
Paul T
PT
D000015:Abnormalities, Multiple / Q000235:genetics; D000818:Animals; D001478:Basal Cell Nevus Syndrome / Q000235:genetics* / Q000473:pathology; D016923:Cell Death; D002455:Cell Division; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9; D002972:Cleft Palate / Q000235:genetics; D017931:DNA Primers; D004195:Disease Models, Animal; D053823:Hedgehog Proteins / Q000235:genetics*; D006801:Humans; D017403:In Situ Hybridization; D053547:Keratin-14 / Q000235:genetics; D008527:Medulloblastoma / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D014070:Tooth / Q000196:embryology / Q000254:growth & development* / Q000473:pathology
D017931:DNA Primers; D053823:Hedgehog Proteins; D053547:Keratin-14; C509239:SHH protein, human; C465570:Shh protein, mouse