Biomedical subjects

Hidetaka Sakai

Publications and source records attributed to Hidetaka Sakai.

5 recordsLinked to original sources

PubMed2006

Transcription promoter activity of the human S100A7 gene in oral squamous cell carcinoma cell lines.

The S100A7 (psoriasin) gene has been shown to be markedly over-expressed in squamous cell carcinomas (SCCs) as well as in psoriasis. We herein examined the S100A7 gene promoter activity in human oral SCC cell lines to identify the putative SCC-specific regulatory regions for the S100A7 transcription. Functional deletion assays of 5'-flanking region demonstrated that the segments, (-1513 to -988), (-1954 to -1513) and (-3040 to -2578), play important roles in the transcription activity in the oral SCCs. The internal deletion of the short segments, (-1248 to -1110), (-1109 to -988) and (-1248 to -988), decreased this activity. These segments cloned upstream of the heterologous promoter increased the promoter activity in oral SCC cell line. Electrophoretic mobility shift assays, using the sequence segmental probes, (-1248 to -1110) and (-1109 to -988), showed different DNA-protein complex patterns depending on the types of used cell lines. One of the complexes was only observed in the oral SCCs. These data suggested that the segment from -1513 to -988 contains up-regulatory elements for the transcription activity of the S100A7 gene in oral SCCs.

Calcium-Binding Proteins↗

PubMed2005

Type II/III Runx2/Cbfa1 is required for tooth germ development.

Runx2/Cbfa1 is an essential transcription factor for osteoblast differentiation and bone formation. Runx2/Cbfa1 knockout mice showed both a complete lack of ossification and the developmental arrest of tooth germ. We here report Runx2/Cbfa1 isoform-type specific functional roles in the development of tooth germ by the administration of antisense phosphorothioate oligodioxynucleotides (S-ODNs) into cultured mouse mandibles. The administration of type II/III Runx2/Cbfa1 antisense S-ODNs into the culture media resulted in an arrest of tooth germ growth at the bud-like stage in cultured mandible taken from the 11-day-old embryos, while also causing the inhibition of the differentiation of odontogenic cells into ameloblast and odontoblast in cultured tooth germs taken from the 15-day-old embryos. The expression of dentin matrix protein 1, dentin sialophosphoprotein, amelogenin, and ameloblastin was shown to be markedly suppressed in cultured tooth germ by the semi-quantitative RT-PCR. Meanwhile, no developmental arrest of tooth germ, no inhibition of gene expression, or differentiation of odontogenic cells was observed in samples treated with the type I Runx2/Cbfa1 antisense S-ODNs. The same findings were also observed in either the control or the sense and random sequence S-ODNs-treated samples. These data indicate that the type II/III Runx2/Cbfa1 isoform is closely related to the development and differentiation of tooth germ.

Animals↗

PubMed2005

Possible functional involvement of thymosin beta 4 in developing tooth germ of mouse lower first molar.

We examined the detailed in situ expression pattern of thymosin beta 4 (Tbeta4) in the developing mouse mandibular first molar. Tbeta4 mRNA was expressed in the presumptive dental epithelium at embryonic day 10.5 (E10.5) and in the thickened dental epithelium at E12. An in situ signal was observed in the invaginated epithelial bud at E13, in the enamel organ at E14 and E14.5, and in the primary enamel knot (PEK) at E14.5. The signal was localized in the epithelial cells of the outer layer of the enamel organ at E15 and E15.5. No signal was found in the PEK at these stages. Tbeta4 mRNA was expressed in the inner enamel epithelium, cervical loop and dental lamina at E16 and E17. The expression of Tbeta4 mRNA was observed in the polarized inner epithelial cells at E18, newborn day 1 (N1) and N2. However, the signal intensity decreased markedly at N3. We herein report for the first time that Tbeta4 is distinctly expressed in developing tooth germ, and it may also play functional roles in the initiation, growth and differentiation of tooth germ.

Animals↗

PubMed2005

Effect of SCCA1 and SCCA2 on the suppression of TNF-alpha-induced cell death by impeding the release of mitochondrial cytochrome c in an oral squamous cell carcinoma cell line.

This study examined the effect of squamous cell carcinoma antigen 1 (SCCA1) and SCCA2 on TNF-alpha-induced cell death in human oral squamous cell carcinoma cell lines. The viability of MISK81-5 and sMISK cells treated with TNF-alpha dose-dependently decreased. The sMISK cells which stably overexpressed SCCA1 and SCCA2 cDNA showed a greater resistance against the cell death induced by TNF-alpha than the controls. Immunocytochemical staining for cytochrome c showed a punctate pattern in the cytoplasm of the TNF-alpha-untreated cells. After treatment with TNF-alpha, the punctate staining pattern was preserved in the transfectants, while this pattern disappeared in the controls. In the transfectants, the release of cytochrome c from the mitochondria to cytosol after TNF-alpha treatment was lower than in the controls. A decreased level of active caspase-9 was also observed in the transfectants. These results suggest that both SCCA1 and SCCA2 play a role in the prevention of TNF-alpha-induced cell death in vitro, by inhibiting the release of mitochondrial cytochrome c to some degree.

Antigens, Neoplasm↗

PubMedDate not supplied

In situ expression of heat shock proteins, Hsc73, Hsj2 and Hsp86 in the developing tooth germ of mouse lower first molar.

This study examined the detailed gene expression pattern of three different heat shock proteins (HSPs), Hsc73, Hsj2, and Hsp86, by means of an in situ hybridization method. Hsc73, Hsj2, and Hsp86 were shown in our previous study to be differentially expressed in the mouse embryonic mandible at day 10.5 (E10.5) gestational age. These HSP genes showed similar expression patterns during development of the mouse lower first molar. HSPs-expressing cells were widely distributed in both the epithelial and underlying ectomesenchymal cells at E10.5, and then were slightly localized at E12 in an area where the tooth germ of the lower first molar is estimated to be formed. A strong expression of HSPs was observed in the tooth germ at E13.5. At the cap stage, HSPs were expressed in the enamel organ and dental papilla. At the bell stage, HSPs were distinctly expressed in the inner enamel epithelium and dental papilla cells facing the inner enamel epithelial layer, which later differentiate into ameloblasts and odontoblasts, respectively. This study is the first report in which Hsc73, Hsj2, and Hsp86 were distinctly expressed in the developing tooth germ, thus suggesting these HSPs are related to the development and differentiation of odontogenic cells.

Animals↗