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PLoS Genet. 2013;9(9):e1003781. doi: 10.1371/journal.pgen.1003781. Epub 2013 Sep 5.

Hsp104 suppresses polyglutamine-induced degeneration post onset in a drosophila MJD/SCA3 model.

Author information

  • 1Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America ; Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America ; Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.

Abstract

There are no effective therapeutics that antagonize or reverse the protein-misfolding events underpinning polyglutamine (PolyQ) disorders, including Spinocerebellar Ataxia Type-3 (SCA3). Here, we augment the proteostasis network of Drosophila SCA3 models with Hsp104, a powerful protein disaggregase from yeast, which is bafflingly absent from metazoa. Hsp104 suppressed eye degeneration caused by a C-terminal ataxin-3 (MJD) fragment containing the pathogenic expanded PolyQ tract, but unexpectedly enhanced aggregation and toxicity of full-length pathogenic MJD. Hsp104 suppressed toxicity of MJD variants lacking a portion of the N-terminal deubiquitylase domain and full-length MJD variants unable to engage polyubiquitin, indicating that MJD-ubiquitin interactions hinder protective Hsp104 modalities. Importantly, in staging experiments, Hsp104 suppressed toxicity of a C-terminal MJD fragment when expressed after the onset of PolyQ-induced degeneration, whereas Hsp70 was ineffective. Thus, we establish the first disaggregase or chaperone treatment administered after the onset of pathogenic protein-induced degeneration that mitigates disease progression.

PMID:
24039611
[PubMed - indexed for MEDLINE]
PMCID:
PMC3764203
Free PMC Article

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