Misfolded proteins partition between two distinct quality control compartments

Nature. 2008 Aug 28;454(7208):1088-95. doi: 10.1038/nature07195.

Abstract

The accumulation of misfolded proteins in intracellular amyloid inclusions, typical of many neurodegenerative disorders including Huntington's and prion disease, is thought to occur after failure of the cellular protein quality control mechanisms. Here we examine the formation of misfolded protein inclusions in the eukaryotic cytosol of yeast and mammalian cell culture models. We identify two intracellular compartments for the sequestration of misfolded cytosolic proteins. Partition of quality control substrates to either compartment seems to depend on their ubiquitination status and aggregation state. Soluble ubiquitinated misfolded proteins accumulate in a juxtanuclear compartment where proteasomes are concentrated. In contrast, terminally aggregated proteins are sequestered in a perivacuolar inclusion. Notably, disease-associated Huntingtin and prion proteins are preferentially directed to the perivacuolar compartment. Enhancing ubiquitination of a prion protein suffices to promote its delivery to the juxtanuclear inclusion. Our findings provide a framework for understanding the preferential accumulation of amyloidogenic proteins in inclusions linked to human disease.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cytosol / metabolism
  • HeLa Cells
  • Humans
  • Prions / metabolism
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Folding*
  • Proteins / chemistry
  • Proteins / metabolism*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Solubility
  • Ubiquitin-Conjugating Enzymes / genetics
  • Ubiquitin-Conjugating Enzymes / metabolism
  • Ubiquitination
  • Von Hippel-Lindau Tumor Suppressor Protein / chemistry
  • Von Hippel-Lindau Tumor Suppressor Protein / genetics
  • Von Hippel-Lindau Tumor Suppressor Protein / metabolism

Substances

  • Prions
  • Proteins
  • Ubiquitin-Conjugating Enzymes
  • Von Hippel-Lindau Tumor Suppressor Protein
  • Proteasome Endopeptidase Complex
  • ubiquitin-conjugating enzyme UBC9