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PolyQ proteins interfere with nuclear degradation of cytosolic proteins by sequestering the Sis1p chaperone.
Park, Sae-Hun; Kukushkin, Yury; Gupta, Rajat; Chen, Taotao; Konagai, Ayano; Hipp, Mark S; Hayer-Hartl, Manajit; Hartl, F Ulrich.
Afiliação
  • Park SH; Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany.
Cell ; 154(1): 134-45, 2013 Jul 03.
Article em En | MEDLINE | ID: mdl-23791384
Dysfunction of protein quality control contributes to the cellular pathology of polyglutamine (polyQ) expansion diseases and other neurodegenerative disorders associated with aggregate deposition. Here we analyzed how polyQ aggregation interferes with the clearance of misfolded proteins by the ubiquitin-proteasome system (UPS). We show in a yeast model that polyQ-expanded proteins inhibit the UPS-mediated degradation of misfolded cytosolic carboxypeptidase Y(∗) fused to green fluorescent protein (GFP) (CG(∗)) without blocking ubiquitylation or proteasome function. Quantitative proteomic analysis reveals that the polyQ aggregates sequester the low-abundant and essential Hsp40 chaperone Sis1p. Overexpression of Sis1p restores CG(∗) degradation. Surprisingly, we find that Sis1p, and its homolog DnaJB1 in mammalian cells, mediates the delivery of misfolded proteins into the nucleus for proteasomal degradation. Sis1p shuttles between cytosol and nucleus, and its cellular level limits the capacity of this quality control pathway. Upon depletion of Sis1p by polyQ aggregation, misfolded proteins are barred from entering the nucleus and form cytoplasmic inclusions.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Peptídeos / Saccharomyces cerevisiae / Dobramento de Proteína / Proteólise Limite: Humans Idioma: En Revista: Cell Ano de publicação: 2013 Tipo de documento: Article País de afiliação: Alemanha

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Peptídeos / Saccharomyces cerevisiae / Dobramento de Proteína / Proteólise Limite: Humans Idioma: En Revista: Cell Ano de publicação: 2013 Tipo de documento: Article País de afiliação: Alemanha