Protein misfolding specifies recruitment to cytoplasmic inclusion bodies

Kirill Bersuker, Michael Brandeis, Ron R. Kopito*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Inclusion bodies (IBs) containing aggregated disease-associated proteins and polyubiquitin (poly-Ub) conjugates are universal histopathological features of neurodegenerative diseases. Ub has been proposed to target proteins to IBs for degradation via autophagy, but the mechanisms that govern recruitment of ubiquitylated proteins to IBs are not well understood. In this paper, we use conditionally destabilized reporters that undergo misfolding and ubiquitylation upon removal of a stabilizing ligand to examine the role of Ub conjugation in targeting proteins to IBs that are composed of an N-terminal fragment of mutant huntingtin, the causative protein of Huntington's disease. We show that reporters are excluded from IBs in the presence of the stabilizing ligand but are recruited to IBs after ligand washout. However, we find that Ub conjugation is not necessary to target reporters to IBs. We also report that forced Ub conjugation by the Ub fusion degradation pathway is not sufficient for recruitment to IBs. Finally, we find that reporters and Ub conjugates are stable at IBs. These data indicate that compromised folding states, rather than conjugation to Ub, can specify recruitment to IBs.

Original languageAmerican English
Pages (from-to)229-241
Number of pages13
JournalJournal of Cell Biology
Volume213
Issue number2
DOIs
StatePublished - 1 Apr 2016

Bibliographical note

Publisher Copyright:
© 2016 Bersuker et al.

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