2006 Fiscal Year Final Research Report Summary
The role of basement membrane type heparan sulfate proteoglycan, perlecan, in epithelial morphogenesis -transgenic mice overexpressing perlecan in the epithelial cells-
| Project/Area Number |
17591902
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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 | Niigata University |
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Principal Investigator |
IDA Hiroko Niigata University, Graduate School of Medical and Dental Sciences, Researcher, 大学院医歯学総合研究科, 科研費研究員 (60293213)
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| Co-Investigator(Kenkyū-buntansha) |
MARUYAMA Satoshi Niigata University, Institute of Medicine and Dentistry, Assistant, 医歯学系, 助手 (30397161)
SATOH Toshiya Niigata University, Brain Research Institute, Assistant, 脳研究所, 助手 (90359703)
CHENG Jun Niigata University, Institute of Medicine and Dentistry, Associate Professor, 医歯学系, 助教授 (40207460)
SAKU Takashi Niigata University, Institute of Medicine and Dentistry, Professor, 医歯学系, 教授 (40145264)
SUZUKI Makoto Niigata University, Medical and Dental Hospital, Lecturer, 医歯学総合病院, 講師 (50107778)
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| Project Period (FY) |
2005 – 2006
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| Keywords | heparan sulfate proteoglycan / perlecan / transgenic mice / overexpression / enamel organ / stellate reticulum / intraepithelial stoma / keratin 5 promoter |
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| Research Abstract |
Perlecan, a basement membrane-type heparan sulfate proteoglycan, is localized in the intercellular space of the enamel organ. Hence, it has been suggested to play an important role in tooth morphogenesis. To elucidate the function of perlecan in odontogenesis, we generated transgenic mice overexpressing perlecan in the epithelial cells using a keratin 5 promoter, and examined the effect of perlecan overexpression on enamel organ formation. Transgenic mice were generated by pronuclear microinjection of fertilized C57BL/C3H F1 oocytes with the DNA construct, and they express the entire perlecan core protein under the control of a bovine keratin 5 promoter. Their molar tooth germs were studied by EM, immunohistochemistry, and RT-PCR for perlecan and tooth germ-related molecules.
Perlecan was immunohistochemically confirmed to be expressed strongly in epithelial tissues, including the enamel organ of Tg mice. Morphologically, the stellate reticulum of the Tg molars showed widened intercellu
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lar spaces and thick, irregularly shaped dental laminae at the embryonic stage (E13-E18). In postnatal day 1 (P1) Tg mice, the enamel organ was obviously lacking cell density and was less vascularized. Finally, the crown shape of Tg molars became dull-ended, with incomplete crystallization and divergent tooth roots in mandibular molars. mRNA expression levels for FGF-2, TGF-β1, and PKC-a were elevated in Tg tooth germs at P1.
From these results, it was suggested that perlecan may control the space arrangement of stromata by binding and releasing of growth factors, and it may act as a carrier for nutrient transport by diffusion within the epithelial milieu. Also in the process of odontogenesis, perlecan might contribute in forming highly hydrated circumstances to realize cell growth and differentiation in the enamel organ. However, the time schedule of the intraepithelial expression of perlecan seems to be critically controlled, because a constant overexpression perlecan has interfered normal tooth morphogenesis. Less
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