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Trapping of normal EB1 ligands in aggresomes formed by an EB1 deletion mutant

Riess, N.P., Milward, K., Lee, T., Adams, M., Askham, J.M. and Morrison, E.E. (2005) Trapping of normal EB1 ligands in aggresomes formed by an EB1 deletion mutant. BMC Cell Biology, 6 (17). ISSN 1471-2121

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Abstract

Background

EB1 is a microtubule tip-associated protein that interacts with the APC tumour suppressor protein and the p150glued subunit of dynactin. We previously reported that an EB1 deletion mutant that retains both of these interactions but does not directly associate with microtubules (EB1-ΔN2-GFP) spontaneously formed perinuclear aggregates when expressed in COS-7 cells.

Results

In the present study live imaging indicated that EB1-ΔN2-GFP aggregates underwent dynamic microtubule-dependent changes in morphology and appeared to be internally cohesive. EB1-ΔN2-GFP aggregates were phase-dense structures that displayed microtubule-dependent accumulation around the centrosome, were immunoreactive for both the 20s subunit of the proteasome and ubiquitin, and induced the collapse of the vimentin cytoskeleton. Fractionation studies revealed that a proportion of EB1-ΔN2-GFP was detergent-insoluble and ubiquitylated, indicating that EB1-ΔN2-GFP aggregates are aggresomes. Immunostaining also revealed that APC and p150glued were present in EB1-ΔN2-GFP aggregates, whereas EB3 was not. Furthermore, evidence for p150glued degradation was found in the insoluble fraction of EB1-ΔN2-GFP transfected cultures.

Conclusion

Our data indicate that aggresomes can be internally cohesive and may not represent a simple "aggregate of aggregates" assembled around the centrosome. Our observations also indicate that a partially misfolded protein may retain the ability to interact with its normal physiological ligands, leading to their co-assembly into aggresomes. This supports the idea that the trapping and degradation of co-aggregated proteins might contribute to human pathologies characterised by aggresome formation.

Item Type: Article
Copyright, Publisher and Additional Information: © 2005 Riess et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Academic Units: The University of Leeds > Faculty of Medicine and Health (Leeds) > Institute of Molecular Medicine (LIMM) (Leeds) > Section of Genetics (Leeds)
Depositing User: Repository Officer
Date Deposited: 13 Mar 2006
Last Modified: 08 Feb 2013 17:02
Published Version: http://www.biomedcentral.com/1471-2121/6/17
Status: Published
Refereed: Yes
Identification Number: 10.1186/1471-2121-6-17
URI: http://eprints.whiterose.ac.uk/id/eprint/1058

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