| Project/Area Number |
15590261
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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 |
General medical chemistry
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| Research Institution | Chiba Cancer Center Research Institute |
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Principal Investigator |
OZAKI Toshinori Chiba Cancer Center Research Institute, Division of Biochemistry, Senior Researcher, 生化学研究部, 上席研究員 (40260252)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAGAWARA Akira Chiba Cancer Center Research Institute, Director, 研究局, 局長 (50117181)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2003: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | p53 / p73 / E3 ligase / ubiquitin / proteasome / RanBPM / UFD2a / apoptosis / E2F1 / NEDL2 / ubiquitination |
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| Research Abstract |
We have found for the first time that E2F-1 has an ability to promote the ubiquitin-dependent proteolytic degradation of p73 in COS7 and SAOS-2 cells. Similar results were also obtained in H1299, U2OS, H4 and A549 cells. Deletion analysis revealed that the transactivation function of E2F-1 is required for the degradation of p73. We also demonstrated that a novel HECT-type E3 ubiquitin protein ligase termed NEDL2 interacts with the PY motif of p73, and thereby inducing its ubiquitination. Unexpectedly, NEDL2-mediated ubiquitination of p73 resulted in an incre ase in its half-life, and enhanced its transcriptional activity. These observations strongly suggest that there exists a non-proteolytic regulatory function of the ubiquitination. By using a yeast-based two-hybrid screening, we have identified RanBPM as a binding partner of p73. RanBPM bound to the extreme COOH-terminal region of p73, and increased its stability by inhibiting the ubiquitination levels of p73. It is likely that the COOH-terminal Lys residues could be target(s) for ubiquitination. In addition, we have found that U-box-type E3/E4 ubiquitin protein ligase termed UFD2a induces the proteasome-dependent proteolytic degradation of p73 through the physical interaction with p73. Of note, UFD2a-mediated ubiquitination of p73 was not detected under our experimental conditions. Thus, our present results indicate that p73 is regulated not only by the ubiquitination-dependent degradation pathway but also by the functional interaction with UFD2a in a ubiquitination-independent manner.
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