2007 Fiscal Year Final Research Report Summary
Studies on molecular mechanisms involved in chondrogenesis by transcription factors
| Project/Area Number |
18390490
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Tokyo University of Science |
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Principal Investigator |
HOZINUI Nobumichi Tokyo University of Science, Reaeasch Institute for Biological Sciences, Professor (60051744)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Mitsuhiro University of Occupational and Environmental Health, Department of Biochemistry, Assistant Professor (00321662)
SHIBUI Akiko Tokyo University of Science, Research Institute for Biological Sciences, Assistant Professor (50313846)
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| Project Period (FY) |
2006 – 2007
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| Keywords | ORtponalein / Runx2 / chondrogenesis / bone regeneration / IL-7 rpepntnra / transcription factors |
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| Research Abstract |
In endochodral ossification occurring in looniituidinal bone, cartilageneous tissue derived from mesenchimal stem cells is replaced with bone within ossification centers. Chondrogenesis precedes bone formation by osteoblasts. Therefore, it is essential to elucidate the molecular mechanisms involved in chondrogenesis for better understanding of bone formation. In the grant years, we investigated regulatory mechanisms of chondrogenesis by transcription factors. As well, we carried out the research projects from the point of view of epigenetic regulation.
Runx2 is a Runt domain transcription factor that regulates osteoblast differentiation and bone formation. The gene expresses the transcripts of Runx2 wt and three alternatively spliced isoforms (ASI) (Runx2Δ5,Δ7 and A5Δ7). These ASIs are generated by skipping exon 5 and/or exon7. Runx2.6.5, and A5Ar7 did not localize in the nucleus and has lost their DNA binding activity. In co-transfection experiments with an osteocalcin (OC) promoter, w
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e confirmed that only Runx2 wt and could upregulate the OC promoter. In addition, the coactivator CBP/p300 enhanced the transcriptional activity of the OC promoter when coexpressed with Runx2 wt or 6,7. These results support the hypothesis that Runx2 both up- and down-regulates its target gene promoters, as exemplified by the OC gene, using various isoforms and context-dependent formation of transcriptional complexes.
Interleukin 7 (IL-7) is a stromal factor produced by epithelial cells in the thymus and bone marrow, The IL-7 receptor (IL-7R) is composed of IL-7Ra and the common cytokine receptor y chain, which is shared by the eceptors for IL-2, -4, -7, -9, -15 and -21. IL-7 is important for the survival of lymphoid cells. The lymphoid cells expressing BCR or TCR do not require the signaling mechanisms provided by IL-7R. Thus, it is of interest to investigate the expression profile of IL=7Ra during the differentiation of lymphoid cells. We have utilized several cell lines including lymphoid cells, myeloid cells and mesenchimal cells.
We have found consensus motifs of PU.1 and Runx1 in the IL-7Ra promoter. We carried out the reporter assay using the mutants with mutations in the transcription motifs. PU.1 motif enhanced the transcriptional activity. We confirmed Runx1activated the promoter activity by the siRNA assay method. The EMSA and ChIP experiments provided us with concrete evidence that Runx1 is a key factor for the transcriptional activity of IL=7a. We identified 6 CpG sites in the promoter region. Four of the six sites demonstrated that the methylation status inversely correlated with IL-7Ra expression. Furthermore, we performed ChIP assay to investigate the relationship between histon acetylation and the transcriptional activity. It was shown that the acetylation status critically regulates the transcriptional activity. We extended our effort to stud the role of MAPK signaling pathway in the regulation of IL-7a promoter. The results indicated that MAPK signals downregulateIL-7Ra expression through the Ets site the IL-7Ra promoter. Less
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Research Products
(11 results)
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[Journal Article] Two of four alternatively Spliced isoforms of RUNX2 control OSTEOCALCIN gene expression in Human osteoblast cells2008
Author(s)
Makita, N., Suzuki, M., Asami, S., Takahata, R., Kohzaki, D., Kobayashi, S., Hakamazuka, T., Hozumi, N
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Journal Title
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Use of the SST-REX method for the Identificationof genes expressed at the condensation stage of chondrogenic Cell line ATDC2006
Author(s)
Noguchi, A., Watanabe, N., Fujimaki, R., Kitamura, T., Hayashizaki, Y., Miyaki, S., Tezuka, K., Hozumin N
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Journal Title
J. Bone Miner. Metab 24
Pages: 153-157
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Site specific DNA methylation By a complex of PU.1 and Dnint3a/b2006
Author(s)
Suzuki, M., Yamada, F., Klhara-Negishi, F., Sakurai, T., Hara, E., Tene, D. G., Hozumi, N., Oikawa, T
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Journal Title
Oncogen 25
Pages: 2477-2488
Description
「研究成果報告書概要(欧文)」より
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