2000 Fiscal Year Final Research Report Summary
Regulation of Function of p53 by Phosphorylation and Acetylation
| Project/Area Number |
11694336
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | NATIONAL CANCER CENTER RESEARCH INSTITUTE |
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Principal Investigator |
TAYA Yoichi National Cancer Center Research Institute, Radiobiology Division, Chief, 放射線研究部, 部長 (60133641)
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| Co-Investigator(Kenkyū-buntansha) |
CAROL Prives Columbia University, Department of Biological Sciences, Professor, 生物科学部, 教授
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| Project Period (FY) |
1999 – 2000
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| Keywords | p53 / Phosphorylation / DNA replication / DNA damage / ATM / Chk2 |
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| Research Abstract |
Upon DNA damage, the amino terminus of p53 is phosphorylated at a number of residues including S20, a site that is particularly important in regulating stability and function of the protein. Because no known kinase has been identified that can modify this site, HeLa nuclear extracts were fractionated and S20 phosphorylation was followed. We discovered that a S20 kinase activity copurifies with the human homolog of the Schizosaccharmyces pombe checkpoint kinase, Chk1 (hCHK1). We confirmed that recombinant hCHK1, but not a kinase-defective version of hCHK1, can phosphorylates p53 in vitro at S20. The human homolog of the second S.pombe checkpoint kinase, Cds1 (CHK2/hCds1), phosphorylates tetrameric p53 but not monomeric p53 in vitro at sites similar to those phosphorylated by hCHK1 kinase, suggesting that both checkpoint kinases can play roles in regulating p53 after DNA damage.
P53 is required for the induction of a G1 and/or G2 irreversible arrest after gamma-irradiation, whereas blocked DNA replication causes a p53-independent S-phase arrest. We have examined the response to p53 when DNA synthesis is blocked by hydroxyurea or aphidicolin or when DNA is damaged by gamma-irradiation. Our results suggest that stalled replication forks activate kinases that modify and stabilize p53, yet act downstream of ATM to impair p53 transcriptional activity.
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