2000 Fiscal Year Final Research Report Summary
The role of cytosolic sialidase in developing enamel organs.
| Project/Area Number |
09671845
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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 |
Morphological basic dentistry
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| Research Institution | Tohoku University |
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Principal Investigator |
AKITA Hirotoshi Tohoku University, Graduate School of Dentistry, assistant professor, 大学院・歯学研究科, 助手 (10108540)
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| Project Period (FY) |
1997 – 2000
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| Keywords | sialoglycoconjugate / cytosolic sialidase / enamel organ / in situ hybridization / immunocytochemistry / lectin-cytochemistry / transmission eletron microscope / rat |
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| Research Abstract |
We obtained following results in in situ hybridization, immunocytochemical, and lectincytochemical studies of rat molar tooth germs.
(1) in situ hybridization study : The level of cytosolic sialidase-mRNAs changed largely with cell differentiation. It was high in the oral epithelium, outer and inner enamel epithelium, and dental papilla. It was very low or barely detectable in the stellate reticulum and transitional cells between the oral epithelium and the outer enamel epithelium, suggesting its steep drop in transition. Although the overall image of the mRNA expression was high in dental papilla, the mesenchymal cells expressed different levels of the mRNAs from each other.
(2) immunocytochemical study : Every cell expressed high levels of cytosolic sialidase-protein in the oral epithelium, enamel organ and dental papilla. The enzyme protein was localized in the cytoplasm, nucleoplasm and mitochondrial matrix of each cell. Its Iocalization pattern was very similar to that in skeletal m
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uscle cells of rats, suggesting it being ubiquitous in many types of cells. Based on the number of immunogold particles, the amount of the enzyme protein did not largely change in cells during the course of cell differentiation. In this point of view the expression of the enzyme protein was different from that of the mRNA.
(3) lectin-cytochemical study : Lectin (Limax flavus)-binding sites were numerous on the cell surface and in the extracellular matrix of tooth germs. However the number of them were small in the cytoplasm. We examined whether a small number of those binding sites were meaningful or not. An inhibitory sugar was effective in decreasing the binding sites at about a half level, indicating the presence of putative cytoplasmic sialoglycoconjugates. The possibility of non-specific lectin binding to the cytoplasm remains to be excluded by conducting a supplementary experiment in which the binding sites are expected to decrease in tissue sections digested by cytosolic sialidase. Less
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