| Project/Area Number |
10670129
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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 | Hiroshima University (2000)
Tokyo Metropolitan Organization for Medical Research (1999)
Tokyo Metropolitan Institute for Neuroscience (1998) |
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Principal Investigator |
YAOITA Yoshio Hiroshima Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (00166472)
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| Co-Investigator(Kenkyū-buntansha) |
中島 圭介 財団法人 東京都医学研究機構, 東京都神経科学総合研究所, 主事研究員 (60260311)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Programmed cell death / apoptosis / Anura / metamorphosis / thyroid hormone / in vivo electroporation / Xenopus laevis / suicide model / 遺伝子導入 / caspase / programmed cell death |
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| Research Abstract |
Our purpose is to clone apoptosis-inducing genes that are induced by thyroid hormone (TH) in the regressing tail of tadpole during amphibian metamorphosis.
1. We have isolated all Xenopus Caspase family genes as apoptosis-excuting genes, and introduced them into tail-derived myoblast cell line. The overexpression of Caspases with a long prodomain showed a strong cell-killing activity. The expression of Xenopus Caspase family genes was upregulated in the regressing tail of metamorphosing tadpole, but was not in dying tail-derived cell line treated with TH, which demonstrates that new RNA synthesis of caspases is dispensable to programmed cell death.
2. Many reports supported the murder model that the increase of secreted extracellular matrixdegrading enzymes induced by TH results in the disruption of the myotendinous junctions, which detaches muscle cells from the extracellular matrix and causes their cell death. However, when TH-signaling was blocked by the enforced expression of dominan
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t-negative thyroid hormone receptor (DNTR), the death of TH-treated myoblast cell line was repressed, suggesting that the programmed cell death takes place through a suicide mechanism. To confirm it, DNTR expression construct was injected into the tail muscle cells of living tadpole with a marker gene, and the activity of marker protein was detected just before tail resorbed completely. The marker gene expression in muscle cells was observed only in tails co-injected with DNTR expression construct. This result indicates that muscle cell dies by suicide as a response to TH in the regressing tail.
3. Tadpole tail was introduced with a marker gene and cDNA library in a expression vector using in vivo electroporation, cut out for the organ culture several days later, and examined on the maker gene expression. Any clone was not isolated as one inhibiting marker gene expression. The overexpression of several genes identified so far by the increased expression in the regressing tail did not show any suppressive activity, either. We are analyzing a group of cDNA clones which has the significant suppressive activity to the marker gene expression in the screening by transfection of tail-derived mvoblastic cell line. Less
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