| Project/Area Number |
08672650
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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 |
Laboratory medicine
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| Research Institution | Showa University |
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Principal Investigator |
GOMI Kunihide Showa University, School of Medicine, Department of Clinical Pathology, Professor, 医学部・臨床病理, 教授 (60053980)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUCHI Kunihiko Showa University, School of Medicine, Department of Clinical Pathology, Lecturer, 医学部・臨床病理, 講師 (70181287)
TAKAGI Yasushi Showa University, School of Medicine, Department of Clinical Pathology, Associat, 医学部・臨床病理, 助教授 (30138490)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | DNA damage / Ionizing radiation / p53 / p21 / ubiquitin / apoptosis / Inhibition of Cell growth / deferoxamine / DNA傷害 / プロテアソーム / 転写後制御 / IRF-1 / γ線 |
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| Research Abstract |
We analyzed the effect of DNA damaging agent on cell growth. DNA damage have been known to induce Gl arrest through activating p53-pRB cascade. In a certain conditions, DNA damage caused the induction of apoptosis. In this investigation, we focused on the regulation of cyclin kinase inhibitor p21, a key component of controlling progression of Gl/S transition.
DNA damages by irradiation or etoposide treatments caused an accumulationof p53 and then caused an increased expression of the p21 gene at both the mRNA and protein levels. However, DNA non-damaging growth inhibiting agent, deferoxamine treatment caused the accumulation of p53 then increase the p21 mPNA level without the appearance of a detectable p21 protein product. A substrate for cyclin kinase, pRB, was unphosphorylated after DNA damage, but remained unaffected by deferoxamine, indicating that p21 was functional only after DNA damage. These data indicated that p21 protein expression was post-transcriotionally regulated. We next investigated the involvement of the ubiquitin proteasome pathway in post-transcriptional regulation of p21. By addition of lactacystin, a proteasome inhibitor, to deferoxamine treatment, the level of unmbiquitinated p21 protein product appeared similar to that induced by etoposide treatment, and the ubiquitinated p21 bands became apparent. After etoposide treatment, the level of ubiquitinated p21 was diminished and a high level of unubiquitinated p21 expression was observed. We concluded that l)efficient expression of p21 protein requires inhibition of the ubiquitin-proteasome pathway, and 2)DNA damage inhibits the ubiquitination of p21.
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