| Project/Area Number |
21591930
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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 |
Orthopaedic surgery
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MIURA Toshiki 東京大学, 医学部附属病院, 講師 (20376479)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAGUCHI Hiroshi 東京大学, 医学部附属病院, 准教授 (40282660)
CHIKUDA Hirotaka 東京大学, 医学部附属病院, 助教 (30345219)
ITOH Ideya 東京大学, 医学部附属病院, 助教 (30436464)
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| Co-Investigator(Renkei-kenkyūsha) |
OGATA Naoshi 東京大学, 医学部附属病院, 講師 (10361495)
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| Project Period (FY) |
2009 – 2011
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| Project Status |
Completed (Fiscal Year 2011)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2011: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2010: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2009: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
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| Keywords | 骨 / 軟骨代謝学 / C/EBPファミリー / Runx2 / 軟骨代謝 / 変形性関節症 / C / EBPファミリー |
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| Research Abstract |
The endochondral ossification is a crucial process in normal skeletal growth and osteoarthritis(OA) development. Aiming at elucidation of the molecular mechanism underlying this process and identification of therapeutic targets for OA, we examined the signal network around CCAAT/enhancer-binding protein-β(C/EBP-β), a regulator of chondrocyte functions. Computational predictions and a C/EBP motif-reporter assay identified RUNX2 as the most potent transcriptional partner of C/EBP-βin chondrocytes.
Both C/EBP-βand RUNX2 were co-expressed in the terminal differentiation stage of chondrocytes in several cell culture systems, in the mouse limb cartilage, and in the OA joint cartilage of mice and humans. To determine the involvement of C/EBP-βand RUNX2 in the endochondral ossification process, we generated their compound knockout mice : Cebpb^<-/->; Runx2^<+/-> and Cebpb^<+/->; Runx2^<+/->, because Runx2^<-/-> mice died just after birth. The Cebpb^<-/->; Runx2^<+/-> mice showed more severe dwa
… More
rfism than the Cebpb^<-/-> and Runx2^<+/-> littermates with impaired cartilage degradation but unaffected chondrocyte differentation. Although Cebpb^<+/->; Runx2^<+/-> mice showed normal skeletal growth, they exhibited greater suppression of knee OA development in surgical and age-related OA models than their Cebpb^<+/-> and Runx2^<+/-> littermates. Histological analyses in the limb cartilage and the OA joint cartilage showed that the compound knockout caused a considerable decrease of matrix metalloproteinase-13(MMP-13) among various factors related to endochondral ossification. In cultured chondrocytes, C/EBP-βand RUNX2 cooperatively enhanced endogenous expression and promoter activity of MMP13 shown by real-time RT-PCR and luciferase assay. The specific and direct binding of C/EBP-βand RUNX2 as a protein complex to a C/EBP-binding motif and an OSE2 motif in the MMP13 promoter was shown by EMSA and ChIP-reIP assay. Lastly, to identify the upstream mechanism, we performed a screening of transcription factors using a human CEBPB promoter fragment among putative factors regulating chondrocyte differentiation, and identified hypoxia-inducible factor-2α(HIF-2α) as the most potent and functional inducer of C/EBP-βexpression in chondrocytes through specific binding to a hypoxia-responsive element. In conclusion, C/EBP-βand RUNX2, with MMP-13 as the target and HIF-2αas the inducer, cooperatively control cartilage degradation. This molecular network in chondrocytes may represent a therapeutic target for OA. Less
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