Cellular stresses induce the nuclear accumulation of importin alpha and cause a conventional nuclear import block.

Abstract

We report here that importin alpha accumulates reversibly in the nucleus in response to cellular stresses including UV irradiation, oxidative stress, and heat shock. The nuclear accumulation of importin alpha appears to be triggered by a collapse in the Ran gradient, resulting in the suppression of the nuclear export of importin alpha. In addition, nuclear retention and the importin beta/Ran-independent import of importin alpha also facilitate its rapid nuclear accumulation. The findings herein show that the classical nuclear import pathway is down-regulated via the removal of importin alpha from the cytoplasm in response to stress. Moreover, whereas the nuclear accumulation of heat shock cognate 70 is more sensitive to heat shock than the other stresses, importin alpha is able to accumulate in the nucleus at all the stress conditions tested. These findings suggest that the stress-induced nuclear accumulation of importin alpha can be involved in a common physiological response to various stress conditions.

• Authors: Yoichi Miyamoto, Takuya Saiwaki, Junichi Yamashita, Yoshinari Yasuda, Ippei Kotera, Satoshi Shibata, Masaki Shigeta, Yasushi Hiraoka, Tokuko Haraguchi, Yoshihiro Yoneda
• Journal: The Journal of cell biology (J Cell Biol) Vol. 165 Issue 5 Pg. 617-23 (Jun 07 2004) ISSN: 0021-9525 [Print] United States
• PMID: 15184398 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright the Rockefeller University Press

Chemical References

• HSP70 Heat-Shock Proteins
• alpha Karyopherins
• ran GTP-Binding Protein

Topics

• Active Transport, Cell Nucleus (genetics)
• Cell Nucleus (genetics, metabolism)
• Down-Regulation (genetics)
• HSP70 Heat-Shock Proteins (genetics, metabolism)
• HeLa Cells
• Heat-Shock Response (genetics)
• Humans
• Oxidative Stress (genetics)
• Protein Transport (genetics)
• Stress, Physiological (genetics, metabolism)
• Ultraviolet Rays
• alpha Karyopherins (genetics, metabolism)
• ran GTP-Binding Protein (metabolism)