| Project/Area Number |
18370083
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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 |
Cell biology
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| Research Institution | The Institute of Physical and Chemical Research |
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Principal Investigator |
IMAMAOTO Naoko The Institute of Physical and Chemical Research, Cellular Dynamics Laboratory, Chief Scientist (20202145)
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| Co-Investigator(Kenkyū-buntansha) |
MAESHIMA Kazuhiro RIKEN, 今本細胞核機能研究室, Senior Staff Scientist (00392118)
KOSE Shingo RIKEN, 今本細胞核機能研究室, Senior Staff Scientist (90333278)
TAKAGI Masatoshi RIKEN, 今本細胞核機能研究室, Senior Staff Scientist (60324779)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥17,510,000 (Direct Cost: ¥15,500,000、Indirect Cost: ¥2,010,000)
Fiscal Year 2007: ¥8,710,000 (Direct Cost: ¥6,700,000、Indirect Cost: ¥2,010,000)
Fiscal Year 2006: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Keywords | Nuclear Pore Complex / Nuclear Envelope / Small GTPase Ran / Cell Cycle / Live imaging / Nucleocvtoplasmic transport / Importin / Mitotic chromosome / Photobleach / 核膜 / マルチ遺伝子発現システム / 細胞核 / CDKインヒビター / インシュレーター / 核内膜 / A-type lamin / B-type lamin / emerin / LBR(Lamin B receptor) / Lap2α |
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| Research Abstract |
Nuclear pores are sophisticated gateways on the nuclear envelope that control macromolecular transport between cytoplasm and nucleoplasm. We have examined a cell cycle-dependent dynamics of nuclear pores, and found their characteristic features, which is common to all human cultured cells examined. Distinct subdomains lacking nuclear pores are present on the nuclear surface of cells in early cell cycle stages. Such pore-free islands gradually become dispersed in Gl-to-S phase. Surprisingly, the islands are enriched with inner nuclear membrane proteins lamin A/C and emerin, but exclude lamin B. Knock-down and ectopic expression analyses demonstrated that lamin A/C, but not emerin, plays an essential structural and regulatory role in the nuclear pore distribution and the formation of pore-free islands. These data thus provide strong evidences that nuclear pore dynamics are regulated by the reorganization of inner nucleat structures. Based on these observations, we have established severa
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l cell lines stably expressing different nuclear pore complex components and inner nuclear envelope components simultaneously to examine the dynamics and formation of nuclear pore components with connection to inner nuclear envelope components. Using theses cell lines, we showed that human POM121 is necessary for nuclear pore formation. Moreover, we have currently succeeded to visualize nuclear pore complex formation, which is strictly regulated by cell-cycle signals.
Nucleocytoplasmic transport proceeds through nuclear pore complexes. During the study, we identified human chromokinesin Kid (hKid) as an import cargo of the importin-α/β transport pathway. Examination in living cells and biochemical analysis using digitonin-permeabilized cells, we found that the association of importins-β and -α with hKid triggers the initial targeting of hKid to mitotic chromosomes and that local Ran-GTP-mediated cargo-release promotes the accumulation of hKid on chromosomes. Thus, our study demonstrates a novel nucleocytoplasmic transport factor-mediated mechanism for targeting proteins to mitotic chromosomes. Less
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