| Project/Area Number |
12213070
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Biological Sciences
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| Research Institution | Osaka University |
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Principal Investigator |
HANAOKA Fumio Osaka Univ., Grad. Sch. Front. Biosci., Professor, 大学院生命機能研究科, 教授 (50012670)
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| Co-Investigator(Kenkyū-buntansha) |
MASUTANI Chikahide Grad. Sch. Front. Biosci., Associate Professor, 大学院生命機能研究科, 助教授 (40241252)
YOKOI Masayuki Grad. Sch. Front. Bbsci., Research Associate, 大学院生命機能研究科, 助手 (00322701)
OHKUMA Yoshiaki Toyama Med. Pharm. Univ., Fac. Pharm. Sci., Professor, 薬学部, 教授 (70192515)
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| Project Period (FY) |
2000 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥67,600,000 (Direct Cost: ¥67,600,000)
Fiscal Year 2004: ¥12,600,000 (Direct Cost: ¥12,600,000)
Fiscal Year 2003: ¥12,600,000 (Direct Cost: ¥12,600,000)
Fiscal Year 2002: ¥13,100,000 (Direct Cost: ¥13,100,000)
Fiscal Year 2001: ¥11,300,000 (Direct Cost: ¥11,300,000)
Fiscal Year 2000: ¥18,000,000 (Direct Cost: ¥18,000,000)
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| Keywords | XP variant / translesion synthesis / DNA polymerase / DNA lesions / knockout mice / carcinogenesis / 遺伝子ノックアウト / REV1 / DNAポリメラーゼ / DNA修復 / 色素性乾皮症 / polイータ / DNA複製 / 活性酸素 / XPVポリメラーゼ / 紫外線 |
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| Research Abstract |
In order to understand the molecular mechanisms of translesion synthesis and the relationships between carcinogenesis and translesion synthesis, we studied various aspects of translesion synthesis with special reference on human DNA polymerase η (Pol η) and obtained following results.
1. Human Pol η copies undamaged DNA with much lower fidelity than any other template-dependent DNA polymerase studied. On the other hand, human Pol η catalyzes efficient and accurate translesion synthesis past cic-syn cyclobutane di-thymine lesions, AAF-modified guanine, and a cisplatin-induced intrastrand cross-link between two guanines.
2. Human Pol η gene consists of 11 exons covering the entire coding region of the transcription-initiation, and the genomic DNA analysis suggested that three of four XP-V cell lines have homozygous mutations, and one of them have heterozygous point mutations, one of which is a splice mutation of the major allele.
3. Human Pol η binds template/primer DNAs regardless of TT dimers. Rather, enhanced binding to template/primer DNAs containing TT dimers is only observed when the 3-end of the primer is an adenosine residue situated opposite the lesion. When two nucleotides have been incorporated into the primer beyond the TT dimer position, the Pol η-template/primer DNA complex is destabilized.
4. In order to make a good in vivo model to study the high incidence of skin carcinogenesis in XP-V patients, we disrupted the mouse Pol η gene in ES cells by replacing exon 8 with the neo^r gene. Mice that are homozygous for the null mutation are viable, fertile and did not show any obvious defects during their first year of life. Pol η-deficient fibroblasts derived from the mutant mice have reduced capacity to replicate UV-damaged DNA. Pol η-deficient mice developed skin tumors after UVB-irradiation, while wild-type and heterozygous littermates did not.
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