| Project/Area Number |
13480240
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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 | RIKEN (2002)
National Institute of Genetics (2001) |
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Principal Investigator |
IMAMOTO Naoko RIKEN, Cellular Dynamics Laboratory, Chief Scientist, 細胞核機能研究室, 主任研究員 (20202145)
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| Co-Investigator(Kenkyū-buntansha) |
KOSE Shingo RIKEN, Cellular Dynamics Laboratory, Research Scientist, 細胞核機能研究室, 研究員 (90333278)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2002: ¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 2001: ¥8,600,000 (Direct Cost: ¥8,600,000)
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| Keywords | nuclear transport / importin β / CAS / small GTPase Ran / importin α / nuclear pore complex / 70kDa heat-shock cognate protein (hsc70) / β-catenin / 核内輸送担体importinβ / 核外輸送担体CAS / 核膜孔複合体 / p10 / NTF2 / hsc70 / 輸送担体 / リサイクリング |
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| Research Abstract |
1.We have initially examined nuclear import and export of importin β in living cells, and found that its nuclear export depends on the presence of energy sources, whereas its import occurs in an energy-independent manner. Analysis in digitonin-permeabilized cell-free system and through the fractionation studies of cytosol, we found that nuclear export of importin β is stimulated not only by small GTPase Ran but also by 70kDa heat-shock cognate protein (hsc70). Point mutated hsc70 lacking ATPase did not stimulate nuclear export of importin β. Our results indicate that additional factor is involved in recycling of importin β and the stimulation is dependent on ATPase activity. 2.β-catenin is an example of a typical molecule that can be bi-directionally translocated through nuclear pore complexes (NPC) on its own in a facilitated manner. We examined the nuclear import and export of β-catenin, and showed that region of β-catenin required for import and export substantially overlapped. However, different nucleocytoplasmic shuttling molecules such as importin β and GAS, differentially blocked nuclear import and export of β-catenin. The different effect was also observed under the condition that induces recycling of transport factor. These data indicates that β-catenin shows an overlapping sequence requirement for its import and export, but that bi-directional movement through the NPC proceeds through distinct molecular interactions. 3.We found that importin α/β mediated nuclear import pathway is down-regulated in response to heat-shock, which was caused by nuclear retention and recycling inhibition of importin α. Such regulation of transport suggests a new regulatory mechanism for the adaptation of cells to environmental changes, such as heat-shock.
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