| Project/Area Number |
15209004
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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 |
Environmental pharmacy
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| Research Institution | Tohoku University |
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Principal Investigator |
NAGANUMA Akira Tohoku University, Graduate School of Pharmaceutical Sciences, Professor, 大学院・薬学研究科, 教授 (80155952)
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| Co-Investigator(Kenkyū-buntansha) |
KUGE Shusuke Tohoku University, Graduate School of Pharmaceutical Sciences, Associate Professor, 大学院・薬学研究科, 助教授 (50186376)
OHASHI Kazuaki Osaka University, Graduate School of Pharmaceutical Sciences, Research Associate, 大学院・薬学研究科, 助手 (70344679)
KWANG Gi-Wook Tohoku University, Graduate School of Pharmaceutical Sciences, Research Associate, 大学院・薬学研究科, 助手 (00344680)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥50,700,000 (Direct Cost: ¥39,000,000、Indirect Cost: ¥11,700,000)
Fiscal Year 2005: ¥10,660,000 (Direct Cost: ¥8,200,000、Indirect Cost: ¥2,460,000)
Fiscal Year 2004: ¥19,500,000 (Direct Cost: ¥15,000,000、Indirect Cost: ¥4,500,000)
Fiscal Year 2003: ¥20,540,000 (Direct Cost: ¥15,800,000、Indirect Cost: ¥4,740,000)
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| Keywords | methylmercury / toxicity / resistance / ubiquitin / F-box proteins / Cdc34 / Rad23 / 酵母 |
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| Research Abstract |
We have identified a gene, CDC34 that confers resistance to methylmercury in Saccharomyces cerevisiae by screening a yeast genomic DNA library. CDC34 encodes one of the ubiquitin-conjugating enzymes (Cdc34) that catalyze ubiquitin transfer onto substrate proteins, an important step for protein degradation via ubiquitin-proteasome pathway. In yeast cells, the ubiquitin-conjugating activity of Cdc34 is essential for the Cdc34-mediated resistance to methylmercury. It is possible to conclude that proteins involved in expression of methylmercury toxicity might exist in the cells and the proteins are degraded after its ubiquitination in proteasomes. In ubiquitin system, substrate proteins are recognized by F-box proteins and ubiquitinated by ubiquitin-conjugating enzymes. Thus, we searched F-box proteins which confer resistance to methylmercury, and found that Hrt3 and Ylr224w have role in protection against methylmercury toxicity. Proteins that bind to these F-box proteins might have activity to intensify the toxicity of methylmercury. We identified three proteins that bind to the F-box proteins, Hrt3 and Ylr224w. Overexpression of the genes for these proteins conferred a hyper susceptibility to methylmercury. Moreover, these proteins are found to be ubiquitinated in the cells. These results suggest that the F-box protein-bounding proteins identified by the present study have significant roles in expression of methylmercury toxicity and are decomposed by the ubiquitin-proteasome pathway. Two of these proteins are enzymes involved in synthesis of pyruvate, and overexpression of these proteins might increase cellular concentration of pyruvate. Addition of excess pyruvate into the culture medium significantly prevents toxicity of methylmercury. Increase in cellular production of pyruvate might have an important role in enhancement of toxicity of methylmercury.
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