title: The DNAJB6 and DNAJB8 protein chaperones prevent intracellular aggregation of polyglutamine peptides.
abstract: Fragments of proteins containing an expanded polyglutamine (polyQ) tract are thought to initiate aggregation and toxicity in at least nine neurodegenerative diseases, including Huntington's disease. Because proteasomes appear unable to digest the polyQ tract, which can initiate intracellular protein aggregation, preventing polyQ peptide aggregation by chaperones should greatly improve polyQ clearance and prevent aggregate formation. Here we expressed polyQ peptides in cells and show that their intracellular aggregation is prevented by DNAJB6 and DNAJB8, members of the DNAJ (Hsp40) chaperone family. In contrast, HSPA/Hsp70 and DNAJB1, also members of the DNAJ chaperone family, did not prevent peptide-initiated aggregation. Intriguingly, DNAJB6 and DNAJB8 also affected the soluble levels of polyQ peptides, indicating that DNAJB6 and DNAJB8 inhibit polyQ peptide aggregation directly. Together with recent data showing that purified DNAJB6 can suppress fibrillation of polyQ peptides far more efficiently than polyQ expanded protein fragments in vitro, we conclude that the mechanism of DNAJB6 and DNAJB8 is suppression of polyQ protein aggregation by directly binding the polyQ tract.
authors.affiliation: Department of Cell Biology and Histology, Academic Medical Center, Amsterdam 1105AZ, The Netherlands.
authors.forename: Judith
authors.initials: J
authors.lastname: Gillis
authors.forename: Sabine
authors.initials: S
authors.lastname: Schipper-Krom
authors.forename: Katrin
authors.initials: K
authors.lastname: Juenemann
authors.forename: Anna
authors.initials: A
authors.lastname: Gruber
authors.forename: Silvia
authors.initials: S
authors.lastname: Coolen
authors.forename: Rian
authors.initials: R
authors.lastname: van den Nieuwendijk
authors.forename: Henk
authors.initials: H
authors.lastname: van Veen
authors.forename: Hermen
authors.initials: H
authors.lastname: Overkleeft
authors.forename: Joachim
authors.initials: J
authors.lastname: Goedhart
authors.forename: Harm H
authors.initials: HH
authors.lastname: Kampinga
authors.forename: Eric A
authors.initials: EA
authors.lastname: Reits
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D057809:HEK293 Cells; D050956:HSP40 Heat-Shock Proteins / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D018832:Molecular Chaperones / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D012995:Solubility
chemical_list: C485565:DNAJB6 protein, human; C582953:DNAJB8 protein, human; D050956:HSP40 Heat-Shock Proteins; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D010455:Peptides; C097188:polyglutamine
keywords: Confocal Microscopy; DNAJB; Huntington's Disease; Molecular Chaperone; Peptides; Polyglutamine Disease