2001 Fiscal Year Final Research Report Summary
Selective elimination mechanism of extrachromosomal autonomously replicating genetic element mediated by the micronucleation
| Project/Area Number |
11440220
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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 |
遺伝
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SHIMIZU Noriaki Hiroshima Univ., Fac. Integ. Arts & Sci., Assoc. Prof., 総合科学部, 助教授 (10216096)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Extrachromosomal DNA / Gene amplification / Double Minutes / Homogeneously Staining Region / DNA replication / Plasmid / Gene Delivery / Micronucleus |
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| Research Abstract |
Amplification of oncogene or drug resistance gene plays a pivotal role in human oncogenesis. The amplified genes most likely reside on extrachromosomal autonomously replicating double minute chromatin (DMs). We previously found that the tumor cells revert their malignant phenotype and differentiate if the DMs were eliminated from the cells. The elimination was mediated by the selective incorporation of DMs into the cytoplasmic micronuclei. In this study, we uncovered the following issues. 1) We clarified the question why DMs were incorporated into micronuclei, by examining the intracellular behavior of DMs during the cell cycle progression. 2) We found that the intranuclear motion of DMs was coupled to their replication, by examining the replication timing of DMs. 3) We obtained the results showing that the DMs in the micronuclei were eliminated from the cells by the extrusion of micronuclei from the cells. Furthermore, we tried to extend the understanding on the behavior of DMs to the wide spectrum of extrachromosomal genetic elements. Therefore, we introduced plasmids having various cis-structure to cancer cell, and examined the 4) short-term, or 5) long-term behavior. The former study revealed that the closed circular plasmids were more rapidly eliminated from the cells than the linear molecules, and that the elimination might be mediated by the p53-dependent active mechanism. The latter study revealed that, if the introduced plasmid could autonomously be replicated, the plasmids generated the DMs or chromosomal HSR. The experimental system will be useful for the evaluation of the autonomous replication driven by the mammalian replication origin. The system also will be an excellent model system to uncover the gene amplification phenomenon seen in cancer cells. Furthermore, the system will be utilized to produce valuable proteins by the amplification of the corresponding genes.
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Research Products
(8 results)
