| Project/Area Number |
17592135
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthodontic/Pediatric dentistry
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| Research Institution | Osaka University |
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Principal Investigator |
OONISHI Tomoyuki Osaka University, Dental Hospital, Research Associate, 歯学部附属病院, 助手 (30303978)
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| Co-Investigator(Kenkyū-buntansha) |
OOSHIMA Takashi Osaka University, Graduate School of Dentistry, Professor, 大学院歯学研究科, 教授 (80116003)
SHINTANI Seikou Osaka University, Graduate School of Dentistry, Associate Professor, 大学院歯学研究科, 助教授 (90273698)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Hyp mouse / Dentin defects / Npt2 / Molecular biology / Hypマウス / Phex |
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| Research Abstract |
The Hyp mouse is a murine homolog of human X-linked hypophosphatemic rickets and displays hypo-mineralization in bone and teeth. Although extrinsic factors, such as hypophosphatemia and deranged vitamin D metabolism, can contribute to the defects of bone and teeth, available evidence indicates the presence of intrinsic abnormalities in bone and teeth of Hyp mice. In the present study, we compared the expression and distribution of type II sodium dependent phosphate cotransporter (Npt2) in developing teeth from wild type (WT) and Hyp mice. Northern blot analysis showed that Npt2b mRNA, an isoform of Npt2, was expressed in mouse molar teeth, though that of Npt2a and 2c was not detected. An in situ hybridization analysis also showed that Npt2b mRNA was distributed in secretory and mature ameloblasts, while young odontoblasts showed strong signals. Further, a quantitative RT-PCR analysis revealed that the amount of Npt2b mRNA in Hyp mouse tooth germs was significantly lower than that in WT mice in both in vivo and in vitro experiments. In addition, tooth germs from WT mice cultured in medium supplemented with antisense oligo-deoxynucleotide for phosphate regulating gene homologies to endopeptidase on the X chromosome (Phex) also showed a reduction of Npt2b mRNA expression. These findings suggest that Npt2b plays a role in tooth formation, while the loss of Phex gene function may be related to the defect in Npt2b expression in Hyp mouse teeth. We suspect that the reduction of Npt2b expression is one of the intrinsic defects in teeth of Hyp mice.
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