2004 Fiscal Year Final Research Report Summary
p53 dependent S checkpoint in early mouse embryos and radiation induction of genomic instability
| Project/Area Number |
14208067
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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 |
環境影響評価(含放射線生物学)
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| Research Institution | Kyoto University |
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Principal Investigator |
NIWA Ohtsura Kyoto University, Radiation Biology Center, Professor, 放射線生物研究センター, 教授 (80093293)
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| Project Period (FY) |
2002 – 2004
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| Keywords | p53 dependent S checkpoint / suppression of replication fork progression / transactivation independent / DNA binding domain / ATM dependency / sperm irradiated zygotes / pink eyed unstable allele / reversion mutation |
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| Research Abstract |
Elevated levels of mutations were found at the maternally derived alleles of the Ms6hm minisatellite locus and the pink-eyed unstable locus in F1 mice born to male mice irradiated at the spermatozoa stage. These mutations demonstrated the operation of untargeted and delayed recombinational mutations due to genomic instability which was induced during early mouse development by radiation DNA damage introduced by the irradiated sperm. In order to elucidate the molecular mechanism of genomic instability, we have undertaken studies of damage response in sperm irradiated mouse embryos.
A p53 responsible reporter plasmid microinjected into zygotes was transcriptionally activated when they zygotes were fertilized with irradiated sperm. This pronuclear cross-talk was found to suppress DNA synthesis of female pronucleus as well as of male pronucleus in sperm irradiated zygotes. This suppression of DNA synthesis was not observed in p53-/-zygotes which was restored when the sperm irradiated p53-/-zygotes were microinjected with p53 protein, suggesting a novel pathway of S checkpoints. Microinjection of mutant p53 proteins into sperm irradiated p53-/-zygotes demonstrated that this p53 dependent S checkpoint required DNA binding domain of p53,but the transactivation domain.
The p53 dependent S checkpoint was analyzed in primary mouse and found operate at doses below 2 Gy. In addition, analyses of DNA fiber elongation by double labeling the cells with Id U and Cld U showedthatthe p53 dependent S checkpoint suppressed DNA synthesis by slowing down of replication fork progression. This slowing down of replication was associated with a higher rate of recombination between sister chromatids which can explain the untargeted recombination of minisatellite. Delayed recombination observed at the pink-eyed unstable allele requires yet another mechanism of damage memory for which much more to be studied yet.
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Author(s)
Kanatsu-Shinohara M, Inoue K, Lee J, Yoshimoto M, Ogonuki N, Miki H, Kato T, Baba S, Kazuki Y, Toyokuni S, Toyoshima M, Niwa O, Oshimura M, Heike T, Ishino F, Nakahata T, Ogura A, Shinohara, T.
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Journal Title
Cell 119
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Description
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Author(s)
Tamura Y, Maruyama M, Mishima Y, Fujisawa H, Obata M, Kodama Y, Yoshikai Y, Aoyagi Y, Niwa O, Schaffner W, Kominami R.
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Journal Title
Oncogene 24
Pages: 399-406
Description
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[Journal Article] Bcll1b is required for differentiation and survival of ab T lymphocytes.2003
Author(s)
Wakabayashi, Y., J.Inoue, J.Sakata, Y.Takahashi, A.Matsuki, H.Kosugi-Okano, Y.Miyazawa, Y.Saito, H.Watanabe, Y.Mixhims, O.Niwa, R.Kominami
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Journal Title
Nature Immunol. 4
Pages: 533-539
Description
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