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Title: The X11L/X11{beta}/MINT2 and X11L2/X11{gamma}/MINT3 scaffold proteins shuttle between the nucleus and cytoplasm

Abstract

The X11/MINT family proteins are adaptor scaffolding proteins involved in formation of multiprotein complexes, and trafficking and metabolism of membrane proteins such as the beta-amyloid precursor protein. We found that a significant portion of X11L and X11L2 are recovered in nuclear fraction of mouse brain homogenates. EGFP-X11s were not detected in the nucleus of N2a neuroblastoma cells; however, administration of leptomycin B (LMB) induced substantial nuclear accumulation of EGFP-X11L and EGFP-X11L2, while EGFP-X11 showed little accumulation. Fluorescence loss in photobleaching (FLIP) analysis indicated that EGFP-X11L2 and EGFP-X11L are shuttled between the cytoplasm and nucleus, the former more effectively than the latter. We identified a nuclear export signal (NES) in the N-terminus of X11L2, mutation of which induces nuclear accumulation of EGFP-X11L2 in the absence of LMB. X11L2 fused to the Gal4 DNA binding domain (DBD) showed transcriptional activity, suggesting that X11L2 could function as a transcriptional activator if tethered near a promoter. Interestingly, attenuation of the nucleo-cytoplasmic shuttling of GAL4-DBD-X11L2 by mutating the NES or attaching the SV40 nuclear localization signal significantly decreased the apparent transcriptional activity. Our observations suggest that X11L2 functions in the nucleus by a mechanism distinct from conventional transactivators.

Authors:
; ; ; ;  [1];  [2]
  1. Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita12-Nishi6, Kita-ku, Sapporo 060-0812 (Japan)
  2. Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita12-Nishi6, Kita-ku, Sapporo 060-0812 (Japan), E-mail: tsuzuki@pharm.hokudai.ac.jp
Publication Date:
OSTI Identifier:
21045953
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Cell Research; Journal Volume: 314; Journal Issue: 5; Other Information: DOI: 10.1016/j.yexcr.2007.12.006; PII: S0014-4827(07)00579-4; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; BRAIN; CELL NUCLEI; CYTOPLASM; DNA; FLUORESCENCE; HOMOGENATES; MEMBRANE PROTEINS; METABOLISM; MICE; MUTATIONS; RABBIT TUBES

Citation Formats

Sumioka, Akio, Saito, Yuhki, Sakuma, Megumi, Araki, Yoichi, Yamamoto, Tohru, and Suzuki, Toshiharu. The X11L/X11{beta}/MINT2 and X11L2/X11{gamma}/MINT3 scaffold proteins shuttle between the nucleus and cytoplasm. United States: N. p., 2008. Web. doi:10.1016/j.yexcr.2007.12.006.
Sumioka, Akio, Saito, Yuhki, Sakuma, Megumi, Araki, Yoichi, Yamamoto, Tohru, & Suzuki, Toshiharu. The X11L/X11{beta}/MINT2 and X11L2/X11{gamma}/MINT3 scaffold proteins shuttle between the nucleus and cytoplasm. United States. doi:10.1016/j.yexcr.2007.12.006.
Sumioka, Akio, Saito, Yuhki, Sakuma, Megumi, Araki, Yoichi, Yamamoto, Tohru, and Suzuki, Toshiharu. Mon . "The X11L/X11{beta}/MINT2 and X11L2/X11{gamma}/MINT3 scaffold proteins shuttle between the nucleus and cytoplasm". United States. doi:10.1016/j.yexcr.2007.12.006.
@article{osti_21045953,
title = {The X11L/X11{beta}/MINT2 and X11L2/X11{gamma}/MINT3 scaffold proteins shuttle between the nucleus and cytoplasm},
author = {Sumioka, Akio and Saito, Yuhki and Sakuma, Megumi and Araki, Yoichi and Yamamoto, Tohru and Suzuki, Toshiharu},
abstractNote = {The X11/MINT family proteins are adaptor scaffolding proteins involved in formation of multiprotein complexes, and trafficking and metabolism of membrane proteins such as the beta-amyloid precursor protein. We found that a significant portion of X11L and X11L2 are recovered in nuclear fraction of mouse brain homogenates. EGFP-X11s were not detected in the nucleus of N2a neuroblastoma cells; however, administration of leptomycin B (LMB) induced substantial nuclear accumulation of EGFP-X11L and EGFP-X11L2, while EGFP-X11 showed little accumulation. Fluorescence loss in photobleaching (FLIP) analysis indicated that EGFP-X11L2 and EGFP-X11L are shuttled between the cytoplasm and nucleus, the former more effectively than the latter. We identified a nuclear export signal (NES) in the N-terminus of X11L2, mutation of which induces nuclear accumulation of EGFP-X11L2 in the absence of LMB. X11L2 fused to the Gal4 DNA binding domain (DBD) showed transcriptional activity, suggesting that X11L2 could function as a transcriptional activator if tethered near a promoter. Interestingly, attenuation of the nucleo-cytoplasmic shuttling of GAL4-DBD-X11L2 by mutating the NES or attaching the SV40 nuclear localization signal significantly decreased the apparent transcriptional activity. Our observations suggest that X11L2 functions in the nucleus by a mechanism distinct from conventional transactivators.},
doi = {10.1016/j.yexcr.2007.12.006},
journal = {Experimental Cell Research},
number = 5,
volume = 314,
place = {United States},
year = {Mon Mar 10 00:00:00 EDT 2008},
month = {Mon Mar 10 00:00:00 EDT 2008}
}