| Project/Area Number |
16591902
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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 |
Pathobiological dentistry/Dental radiology
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| Research Institution | Fukuoka Dental College |
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Principal Investigator |
ITO Riyoko Fukuoka Dental College, Dentistry, Assistant, 歯学部, 助手 (10140865)
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| Co-Investigator(Kenkyū-buntansha) |
SEKIGUCHI Mutsuo Fukuoka Dental College, Frontier Research Center, Professor, 学術フロンティア研究センター, 教授 (00037342)
TAKAGI Yasumitsu Fukuoka Dental College, Frontier Research Center, Assistant professor, 学術フロンティア研究センター, 助教授 (20212003)
SANADA Masayuki Fukuoka Dental College, Dentistry, Lecture, 歯学部, 講師 (40084264)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2005: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | DNA Repair / apoptosis / mutation / alkylated agent / アポトーシス / ミスマッチ修復 / O^6-メチルグアニン / 細胞死 / 抗がん剤 |
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| Research Abstract |
Modified DNA bases which do not prevent progression of the replication fork but cause mispairing are troublesome, since they yield mutation. To prevent such outcomes, multicellular organisms are equipped with a system to eliminate cells with such mispairs by inducing apoptosis. O^6-Methylguanine(O^6mG)-mediated killing pathway would provide an excellent model to reveal this apoptotic defense system. We have shown that defects in one of the mismatch recognition (MMR) proteins block apoptosis and enhance the mutagenic effects of alkylating agents, indicating the essential role of this recognition system in O^6mG-induced apoptosis.
As an early step in the induction of this apoptosis, we detected a protein complex composed of MutSa, MutLa and PCNA on damaged DNA in human cells, by immunoprecipitation method. Time course experiments revealed that MutSa, (MSH2 and MSH6) and PCNA bind to the DNA to form an initial complex, and MutLa, (MLH1 and PMS2), binds to the complex when the DNA is damaged. These observations imply that the induction of this apoptosis is coupled with the progression of DNA replication through the action of PCNA
Since Apaf-1 is activated during apoptosis caused by DNA lesion that block DNA replication, it is important to know if the activation of Apaf-1 is also involved in apoptosis caused by O^6mG. To investigate this problem, we constructed mice defective in the Mgmt gene that encodes O^6mG repair enzyme and/or Apaf-1 gene, and established cell lines from the mice (Mgmt^<-/-> ; Mgmt^<-/->Apaf1^<-/->). These cell lines allowed us to find that Apaf-1 is required for this apoptosis, as in the case of the one induced by cisplatin, which blocks DNA replication. The branching point of the MNU-induced pathway and the one by cisplatin seems to exite somewhere between MMR system and Apaf-1.
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