Dentomaxillofacial characteristics of ectodermal dysplasia.

The aim of this retrospective hospital-based study was to elucidate the dentomaxillofacial characteristics of ectodermal dysplasia. Six Japanese individuals (one male and five female; age range, 12.7-27.2 years) underwent comprehensive examinations, including history recording, cephalometric analysis, panoramic radiography, and analysis of dental models. All the subjects had two or more major manifestations for clinical diagnosis of ectodermal dysplasia (e.g., defects of hair, teeth, nails, and sweat glands). They presented hypodontia (mean number of missing teeth, 9.5; range, 5-14), especially in the premolar region, and enamel dysplasia. Five subjects had bilateral molar occlusion, whereas one subject had unilateral molar occlusion. The common skeletal features were small facial height, maxillary hypoplasia, counterclockwise rotation of the mandible, and mandibular protrusion. Interestingly, the maxillary first molars were located in higher positions and the upper anterior facial height was smaller than the Japanese norm. The results suggest that vertical and anteroposterior maxillary growth retardation, rather than lack of occlusal support due to hypodontia, leads to reduced anterior facial height in individuals with ectodermal dysplasia.

Dental and maxillofacial characteristics of six Japanese individuals with ectrodactyly-ectodermal dysplasia-clefting syndrome.

Objective : Ectrodactyly-ectodermal dysplasia-clefting syndrome is a congenital anomaly characterized by ectodermal dysplasia, ectrodactyly, cleft lip and palate, and lacrimal duct anomalies. Because this syndrome is frequently accompanied by a congenital lack of teeth, narrow palate, and malocclusion, comprehensive orthodontic intervention is required. Design : To highlight the specific dental and maxillofacial characteristics of ectrodactyly-ectodermal dysplasia-clefting syndrome, six Japanese individuals diagnosed with the syndrome are described here. Patients : The subjects consisted of two boys and four girls (age range, 6.0 to 13.9 years) diagnosed with ectrodactyly-ectodermal dysplasia-clefting syndrome by medical and dental specialists. Their conditions included ectodermal dysplasia (hypodontia, microdontia, enamel hypoplasia, and abnormalities in hair and nails), cleft lip and/or palate, and ectrodactyly. Cephalograms, panoramic x-rays, and dental casts were taken; systemic complications were recorded at the first visit to our dental hospital. Results : All individuals had severe oligodontia with 9 to 18 missing teeth. The missing teeth were mainly maxillary and mandibular incisors and second bicuspids, arranged in a symmetrical manner. Cephalometric analysis showed retruded and short maxilla due to cleft lip and/or palate. It is interesting that all individuals showed a characteristically shaped mandibular symphysis with a retruded point B. It is likely that this unusual symphyseal morphology is due to the lack of mandibular incisors. Conclusions : This study demonstrates the presence of severe oligodontia in the incisal and premolar regions and describes a characteristic maxillary and mandibular structure in Japanese individuals with ectrodactyly-ectodermal dysplasia-clefting syndrome.

Molecular mechanism of transforming growth factor-beta-mediated inhibition of growth arrest and differentiation in a myoblast cell line.

Transforming growth factor-beta (TGF-beta) has been demonstrated to inhibit myogenesis in myoblasts. Here we report that transcriptional upregulation of p21(WAF1/Cip1) and muscle creatinine kinase (MCK) genes in C2C12 cells, which are associated with growth arrest at the G1 phase and representative cell-lineage-specific expression during myogenesis, was inhibited by TGF-beta treatment. C2C12 cells expressed TWIST2, but not TWIST1, which was downregulated in myogenic differentiation in response to low-serum cultures. We further found that TGF-beta prevented differentiation-associated downregulation of TWIST2 transcription, resulting in maintaining TWIST2 mRNA expression as high as that in growing C2C12 cells. Ectopic TWIST2 suppressed the p21 and MCK promoters activated by the exogenous addition of E2A and MyoD and this inhibitory effect of TWIST2 was cancelled by the introduction of short hairpin RNA (shRNA) against TWIST2. On the other hand, TWIST2 shRNA failed to recover endogenous promoter activities from TGF-beta-mediated repression. The results clearly indicate that TGF-beta inhibits G1 arrest and maintains TWIST2 expression in C2C12 cells. Our data however suggest that the TGF-beta signaling pathway may not involve TWIST2 to inhibit p21 and MCK expression.

Unique CCT repeats mediate transcription of the TWIST1 gene in mesenchymal cell lines.

TWIST1, a basic helix-loop-helix transcription factor, plays critical roles in embryo development, cancer metastasis and mesenchymal progenitor differentiation. Little is known about transcriptional regulation of TWIST1 expression. Here we identified DNA sequences responsible for TWIST1 expression in mesenchymal lineage cell lines. Reporter assays with TWIST1 promoter mutants defined the -102 to -74 sequences that are essential for TWIST1 expression in human and mouse mesenchymal cell lines. Tandem repeats of CCT, but not putative CREB and NF-kappaB sites in the sequences substantially supported activity of the TWIST1 promoter. Electrophoretic mobility shift assay demonstrated that the DNA sequences with the CCT repeats formed complexes with nuclear factors, containing, at least, Sp1 and Sp3. These results suggest critical implication of the CCT repeats in association with Sp1 and Sp3 factors in sustaining expression of the TWIST1 gene in mesenchymal cells.