| Project/Area Number |
13680754
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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 |
Molecular biology
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| Research Institution | Tohoku University |
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Principal Investigator |
UEHARA Yoshihiko Tohoku University, Graduate School of Medicine, Research Associate, 大学院・医学系研究科, 助手 (30223499)
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| Co-Investigator(Kenkyū-buntansha) |
ONO Tetsuya Tohoku University, Graduate School of Medicine, Professor, 大学院・医学系研究科, 教授 (00107509)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2001: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Thymine DNA Glycosylase(TDG) / DNA repair / Knockout mouse / Embryonic lethality / Mutation / Catecholamine |
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| Research Abstract |
In mammalian cells, methylation of cytosine (5-methylcytosine) at CpG site is thought to play a pivotal role in control of gene expression, embryogenesis, genomic imprinting, and X chromosome inactivation. 5-methylcytosine is also known to be mutagenic because it is dearninated hydrolytically and converted to thyrnine resulting in G;T mismatch formation. Thus, this deamination of 5-methylcytosine is implied to be the main cause of G:C to A:T base substitution.
TDG (mismatch-specific T__-hymine D__-NA G__-lycosylase) is one of the repair enzymes working in removal of thymine mispairing with G at CpG site. We generated TDG (-/-) ES cells by gene targeting in order to investigate its function in vivo. Although TDG (-/-) ES cells had little G-T mismatch glycosylase activity in nicking assay, there is no difference in mutant frequency at Hprt gene between TDG (+/+) and (-/-) ES cells. This result suggests that TDG might not have strong effects on mutation induction in ES cells.
We have also generated TDG (+/-) mice. They are fertile and grow normally however, homozygous mutant (-/-) mice died before ll.5 days post coitum (dpc). Although there was no significant difference in spontaneous mutant frequency between wild type and TDG . (-/-) embryos, we found that the level of noradrenaline, necessary for normal embryogenesis, dramatically reduced in TDG (-/-) embryos. Furthermore, we could partially rescue TDG (-/-) embryos beyind 11.5 dpc by the administration of noradrenaline. These results suggest that the lethality of TDG (-/-) embryo is in parts due to noradrenaline reduction, and TDG is indispensable for embryonic development.
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