Identification of ubiquitin-interacting proteins in purified polyglutamine aggregates

Nuclear aggregates of enhanced green fluorescent protein and nuclear localization signal-fused truncated N-terminal huntingtin containing 150 repeats of glutamine residue were purified from ecdysine-inducible mutant neuro2A cell line by sequential extraction of nuclear soluble proteins. To analyze the aggregate-interacting proteins, we subjected the nuclear aggregates to high performance liquid chromatography-mass spectrometry analysis. The resulting data revealed the presence of three new putative aggregate-interacting proteins: ubiquilin 1, ubiquilin 2 and Tollip. These proteins also associated with neuronal intranuclear inclusions in a mouse model of Huntington disease (HD). These aggregate-interacting proteins contain ubiquitin-interacting motifs, suggesting that they are recruited to the aggregates where they may lose their normal function. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.