Inhibition of proteasomes induces accumulation, phosphorylation, and recruitment of HSP27 and αB-crystallin to aggresomes

被引:64
作者
Ito, H
Kamei, K
Iwamoto, I
Inaguma, Y
García-Mata, R
Sztul, E
Kato, K
机构
[1] Aichi Human Serv Ctr, Inst Dev Res, Dept Biochem, Aichi 4800392, Japan
[2] Univ Alabama Birmingham, Dept Cell Biol, Birmingham, AL 35924 USA
关键词
aggresome; chaperone; crystallin; phosphorylation; proteasome;
D O I
10.1093/oxfordjournals.jbchem.a003139
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Molecular chaperones and the ubiquitin-proteasome pathway are known to participate in the quality control of proteins in cells. In this study, we examined the responses of small heat shock proteins to proteasome inhibitors to clarify their roles under conditions where misfolded proteins are abnormally accumulated. HSP27 and alphaB-crystallin accumulated in both soluble and, more prominently, insoluble fractions after exposure to MG-132, a proteasome inhibitor. Enhanced expression of mRNAs for HSP27 and alphaB-crystallin was observed, suggesting transcriptional activation. Phosphorylation of HSP27 and alphaB-crystallin in cells treated with MG-132 was enhanced concomitantly with activation of p38 and p44/42 MAP kinase pathways. Immunofluorescence analysis revealed that exposure to proteasome inhibitors induced the formation of aggresomes in U373 MG cells, to which HSP27 and alphaB-crystallin were recruited. However, phosphorylation was not required for this accumulation in aggresomes. Thus, HSP27 and alphaB-crystallin are increased, phosphorylated and localized in aggresomes when proteasome activity is inhibited.
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页码:593 / 603
页数:11
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