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Mol Cell Biol. 2018 Nov 13;38(23). pii: e00437-18. doi: 10.1128/MCB.00437-18. Print 2018 Dec 1.

Human DnaJB6 Antiamyloid Chaperone Protects Yeast from Polyglutamine Toxicity Separately from Spatial Segregation of Aggregates.

Author information

1
Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
2
Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA danielmas@niddk.nih.gov.
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Contributed equally

Abstract

Polyglutamine (polyQ) aggregates are associated with pathology in protein-folding diseases and with toxicity in the yeast Saccharomyces cerevisiae Protection from polyQ toxicity in yeast by human DnaJB6 coincides with sequestration of aggregates. Gathering of misfolded proteins into deposition sites by protein quality control (PQC) factors has led to the view that PQC processes protect cells by spatially segregating toxic aggregates. Whether DnaJB6 depends on this machinery to sequester polyQ aggregates, if this sequestration is needed for DnaJB6 to protect cells, and the identity of the deposition site are unknown. Here, we found DnaJB6-driven deposits share characteristics with perivacuolar insoluble protein deposition sites (IPODs). Binding of DnaJB6 to aggregates was necessary, but not enough, for detoxification. Focal formation required a DnaJB6-Hsp70 interaction and actin, polyQ could be detoxified without sequestration, and segregation of aggregates alone was not protective. Our findings suggest DnaJB6 binds to smaller polyQ aggregates to block their toxicity. Assembly and segregation of detoxified aggregates are driven by an Hsp70- and actin-dependent process. Our findings show sequestration of aggregates is not the primary mechanism by which DnaJB6 suppresses toxicity and raise questions regarding how and when misfolded proteins are detoxified during spatial segregation.

KEYWORDS:

DnaJB6; Huntington's disease; J-protein; amyloid; heat shock protein (HSP); molecular chaperone

PMID:
30224519
PMCID:
PMC6234286
DOI:
10.1128/MCB.00437-18
[Indexed for MEDLINE]
Free PMC Article

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