2011 Fiscal Year Final Research Report
Analysis of acid extrusion mechanism through new regulatory protein during bone resorption
| Project/Area Number |
21592381
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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 |
Functional basic dentistry
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| Research Institution | Fukuoka Dental College |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Fujio 福岡歯科大学, 歯学部, 講師 (60153938)
OKABE Kouji 福岡歯科大学, 歯学部, 教授 (80224046)
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| Project Period (FY) |
2009 – 2011
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| Keywords | 骨代謝 / 酸分泌 / Clcn7型Cl-輸送体 / 破骨細胞 / メバロン酸経路 |
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| Research Abstract |
The Clcn7 transporter is crucial for osteoclastic bone resorption and its deficiency or mutations suppress bone resorption and lead to severe osteopetrosis. Farnesyl diphosphate synthase(Fdps) catalyses the formation of an important cellular intermediate in mevalonic acid metabolism. Furthermore, Fdps is inhibited by nitrogen-containing bisphosphonate in mature osteoclasts. Here we describe a novel role for the enzyme in Clcn7 Cl-transporter activity in osteoclasts. Using yeast two-hybrid and co-immunoprecipitation methods, we demonstrate the binding of Fdps to Clcn7 in mouse osteoclasts and Fdps and Clc7 overexpressing HEK cells. Bisphosphonates have been attributed to directly inhibit bone resorption and to promote apoptosis of mature osteoclasts. Furthermore, the main pharmacological mechanism of nitrogen-containing bisphosphonates is to inhibit Fdps. Thus, we examined the effects of an Fdps inhibitor zoledronic acid on the Clcn7 extrusion activity in osteoclasts. Extracellular acidification induced Cl-currents associated with Clcn7, which were upregulated in according to osteoclast differentiation. Zoledronic acid inhibited the acid-activated Cl-current in dose-dependent manner. In contrast a non-nitrogen bisphosphonate etidronic acid has no effects on the acid-activated Cl-current. The tetracycline-induced Fdps silencing significantly decreased the Cl-current. Furthermore, the Cl-current also suppressed the inhibitor of geranylgeranyl transferase. In contrast, zoledronic inhibitory effect was rescued by the addition geranylgeranyl acid a derivative of mebalonic acid. Although extracellular acidification decreased[Cl-] i zoledronic acid significantly suppressed the decrease in[Cl-] i. The results suggest that nitrogen-containing bisphosphonates not only suppress resorbing osteoclast cytoskeleton structure but also inhibit acid extrusion transporter through inhibition of Fdps in mature osteoclasts.
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[Journal Article] Ca^<2+> extrusion via Na^+-Ca^<2+> exchangers in rat odontoblasts2011
Author(s)
Tsumura M, Okumura R, Tatsuyama S, Ichikawa H, Muramatsu T, Matsuda T, Baba A, Suzuki K, Kajiya H, Sahara Y, Tokuda M, Momose Y, Tazaki M, Shimono M, Shibukawa Y
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Journal Title
J Endod
Volume: 36
Pages: 668-674
Peer Reviewed
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