| Project/Area Number |
16209003
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biological pharmacy
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| Research Institution | Osaka University |
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Principal Investigator |
HANAOKA Humio Osaka University, Graduate School of Frontier Biosciences, Professor (50012670)
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| Co-Investigator(Kenkyū-buntansha) |
MASUTANI Chikahide Osaka University, Graduate School of Frontier Biosciences, Associate Professor (40241252)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥47,970,000 (Direct Cost: ¥36,900,000、Indirect Cost: ¥11,070,000)
Fiscal Year 2006: ¥14,430,000 (Direct Cost: ¥11,100,000、Indirect Cost: ¥3,330,000)
Fiscal Year 2005: ¥15,990,000 (Direct Cost: ¥12,300,000、Indirect Cost: ¥3,690,000)
Fiscal Year 2004: ¥17,550,000 (Direct Cost: ¥13,500,000、Indirect Cost: ¥4,050,000)
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| Keywords | DNA repair / chromatin structure / nucleotide excision repair / XPC protein / UV-DDB / ubiquitylation / centrin 2 / condensin / ヒストンアセチル化 / CBP / NER / DDB因子 |
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| Research Abstract |
In order to investigate how chromatin structure influences DNA repair mechanism such as nucleotide excision repair (NER) and translesion synthesis (TLS), we analyzed molecular mechanisms of NER and TLS with special reference to chromatin structure. Followings are summary of our results.
1) In global genome NER, two mammalian homologs of Rad23, HR23A and HR23B, were found to be equivalent in terms of NER functions. In other words, either one of them is enough for NER, if the protein level is sufficient.
2) The specific binding of the XPC complex to (6-4) photoproducts was competitively inhibited by the addition of a large excess ofundamaged naked DNA. In contrast, the addition of undamaged nucleosomal DNA as a competitor suppressed the inhibitory effect. Although nucleosomes positioned on the damaged site inhibited the binding of the XPC complex, the presence of nucleosomes in undamaged DNA regions may help specific binding of the XPC complex to damaged sites by excluding its non-specific binding to damaged DNA regions.
3) XPC undergoes reversible ubiquitylation upon UV irradiation of cells and that this depends on the presence of functional UV-DDB activity. XPC and UV-DDB were demonstrated to interact physically, and both are polyubiquitylated by the recombinant UV-DDB-ubiquitin ligase complex.
4) We have identified three amino acid residues in human XPC protein that are essential for the binding to centrin 2. Alanine substitutions of these amino acids in XPC protein abrogated interaction with centrin 2. Human cell lines stably expressing the mutant XPC protein exhibited a significant reduction on global genome NER activity. Centrin 2 enhanced the cell-free NER dual incision and damaged DNA binding activities of XPC.
5) CK2 phosphorylates condensin I during interphase and reduced its supercoiling activity. On the other hand, CK2-dependent phosphorylation decreases on chromosomes during mitosis. Thus condensin I is regulated by CK2 phosphorylation.
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