| Project/Area Number |
05557082
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | Showa University |
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Principal Investigator |
SUDA Tatsuo Showa University, School of Dentistry, Professor, 歯学部, 教授 (90014034)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Takahisa Showa University, School of Dentistry, Associate Professor, 歯学部, 助教授 (50129839)
YAMAGUCHI Akira Showa University, School of Dentistry, Associate Professor, 歯学部, 助教授 (00142430)
KATAGIRI Takenobu Showa University, School of Dentistry, Assistant, 歯学部, 助手 (80245802)
TAKAHASHI Naoyuki Showa University, School of Dentistry, Associate Professor, 歯学部, 助教授 (90119222)
宇田川 信之 昭和大学, 歯学部, 助手 (70245801)
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| Project Period (FY) |
1993 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥10,300,000 (Direct Cost: ¥10,300,000)
Fiscal Year 1995: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1994: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1993: ¥5,700,000 (Direct Cost: ¥5,700,000)
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| Keywords | osteoclast / bone resorption / screening system / osteoclast formation / osteoclast function / pit formation / calcitonin / bisphosphonates / cAMP / ビイフォスフォネート / チロシンフォスファーゼ / 波状縁 / 明帯 / ポドソーム / アクチンリング形成 / 骨吸収試験 / 骨吸収評価系 / 破骨細胞前駆細胞 / bisphosphonates / ポドソーム形成 / 吸収窩 |
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| Research Abstract |
Using a co-culture system of mouse osteoblastic cells and bone marrow cells, we have established reliable assay systems for examining osteoclast development and function. In a assay system for osteoclast development, chronological changes in phenotypic expression by postmitotic osteoclast precursors were examined during their differentiation into osteoclasts. The mechanism of action of bone resorption-inhibiting agents such as calcitonin and bisphosphonates in bone resorption was also examined in the present study using those assay systems.
(1) Characteristics of postmitotic precursor cells that differentiate into osteoclasts
Characteristics of osteoclast precursors that differentiate into osteoclasts were examined using a co-culture system of mouse osteoblastic cells and bone marrow cells. Postmitotic osteoclast precursors were mononuclear cells which expressed macrophage-associated phenotypes such as nonspecific esterase (NSE), Mac-1 and Mac-2. Some of the macrophage-associated phenoty
… More
pes in osteoclast precursors disappeared rapidly during their differentiation into osteoclasts.
(2) Establishment of assay systems for examining osteoclast function
We have previously established a method for preparing a large number of functionally active osteoclasts from cocultures of mouse osteoblastic cells and bone marrow cells. To examine effects of bone resorption-regulatory factors on osteoclast function, we have developed assay systems for pit formation and actin ring formation using osteoclasts formed in vitro. We have shown that osteclast function is regulated by several signaling patheays mediated by cyclic AMP dependentprotein kinase, tyrosine kiases, phosphatidylinositol-3 kinase, and small GTP binding protein, rho.
Effects of calcitonin and bisphosphonates on osteoclastic bone resorption
The mechanism of inhibitory action of calcitonin and bisphosphonates on bone resorption was examined in established assay systems as described above. Both calcitonin and bisphosphonates inhibited pit forming activity of osteoclasts placed on dentine slices. Only polarized osteoclasts having ruffled borders incorporated bisphosphonates, which inhibited tyrosine phosphatases and disrupted actin rings of osteoclasts. Calcitonin also induced marked changes in osteoclast morphology including disruption of actin rings. This effect was observed in both polarized and non-polarized osteoclasts. Thus, both calcitonin and bisphosphonates suppress osteoclast function, but their mechanisms of action are quite different from each other. Less
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