| Project/Area Number |
08407073
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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 |
Human genetics
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| Research Institution | Osaka University |
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Principal Investigator |
TANAK Kiyoji Osaka University, Institute for Moleculara and Cellular Biology, Professor, 細胞生体工学センター, 教授 (80144450)
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| Co-Investigator(Kenkyū-buntansha) |
SAIJO Masafumi Osaka University, Institute for Molecular and Cellular Biology, Assistant Profes, 細胞生体工学センター, 助手 (90221986)
NAKATSU Yoshimichi Osaka University, Institute for Molecular and Cellular Biology, Assistant Profes, 細胞生体工学センター, 助手 (00207820)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥31,500,000 (Direct Cost: ¥31,500,000)
Fiscal Year 1998: ¥9,800,000 (Direct Cost: ¥9,800,000)
Fiscal Year 1997: ¥10,600,000 (Direct Cost: ¥10,600,000)
Fiscal Year 1996: ¥11,100,000 (Direct Cost: ¥11,100,000)
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| Keywords | DNA repair / transcription / xeroderma pigmentosum / Cockayne syndrome / microinjection / ultraviolet light / skin cancer / gene targeting / 遺伝子ターゲッティング / 基本転写 / 紫外線 / 皮膚癌 / ノックアウトマウス / NMR / RPA |
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| Research Abstract |
Nucleotide excision repair (NER) removes a wide variety of lesions from the genome and is defective in the genetic disorders xeroderma pigmentosum (XP) and Cockayne syndrome (CS). Complementation studies revealed that 7 genes are involved in XP (XPA-XPG) and 2 in CS (GSA, CSB). There are two subpathways in NER : transcription-coupled (TC-)NER accomplishing efficient removal of lesions blocking transcription and the slower global genome (GG-)NER.TFIIH, of which two subunits are XPB and XPD, is an essential component of NER and basal transcription machinery. (1) We showed that TFIIH has some affinity for DNA, but does not show any preference for UV-damaged DNA.TFIIH binds to XPA-DNA complexes in an UV damage-dependent manner by a direct protein-protein interaction with XPA, suggesting that an enhancement of the affinity of XPA protein for TFIIH could arise from conformational changes of XPA when it binds to UV lesions on the DNA.(2) The solution structure of the central domain of XPA was
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determened by NMR spectroscopy. The central domain consists of a zinc-containing subdomain and a C-terminal subdomain. The zinc-containing subdomain has a compact globular structure and is distinct from the zinc-fingers found in transcription factors. The C-terminal subdomain folds into a novel alpha/beta structure with a positively charged superficial cleft. From the NMR spectra of the complexes, DNA and RPA binding surfaces are suggested (3) We recently discovered a novel 855-amino acid protein, XAB2 (XPA-binding protein 2) by virtue of its ability to interact with XPA in yeast two hybrid system. Immunoprecipitation analysis demonstrated that XAB2 is associated with the TC-NER-specific proteins GSA, CSB and RNA polymerase II in vivo. Antibodies against XAB2 inhibited both TC-NER and transcription when microinjected into living fibroblasts. These results indicate that XAB2 is a novel component involved in TC-NER and transcription. (4) We examined the spectrum of p53 mutations found in 40 UV-induced skin tumors of XPA deficient mice. p53 mutations were detected in 48% of the tumors. Almost all the mutations were induced at dipyrimidine sites. 93% of the mutations were C * T and CC * TT transitions. However, 72% of the mutations at dipyrimidine sites could be ascribed to damage on the transcribed strands and no evident mutational hot spots were detected. Thus, XPA deficient mice showed significant mutation features that might be characteristic of the NER deficiency and may provide a good animal model for the analysis of the high incidence of skin cancer in XPA patients.. Less
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