Alteration of familial ALS-linked mutant SOD1 solubility with disease progression: its modulation by the proteasome and Hsp70

Biochem Biophys Res Commun. 2006 May 12;343(3):719-30. doi: 10.1016/j.bbrc.2006.02.170. Epub 2006 Mar 9.


Accumulation of misfolded Cu/Zn superoxide dismutase (SOD1) occurs in patients with a subgroup of familial amyotrophic lateral sclerosis (fALS). To identify the conversion of SOD1 from a normally soluble form to insoluble aggregates, we investigated the change of SOD1 solubility with aging in fALS-linked H46R SOD1 transgenic mice. Mutant SOD1 specifically altered to insoluble forms, which were sequentially separated into Triton X-100-insoluble/sodium dodecyl sulfate (SDS)-soluble and SDS-insoluble/formic acid-soluble species. In spinal cords, the levels of SDS-dissociable soluble SOD1 monomers and SDS-stable soluble dimers were significantly elevated before motor dysfunction onset. In COS-7 cells expressing H46R SOD1, treatment with proteasome inhibitors recapitulated the alteration of SOD1 solubility in transgenic mice. In contrast, overexpression of Hsp70 reduced accumulation of mutant-specific insoluble SOD1. SDS-soluble low molecular weight species of H46R SOD1 may appear as early misfolded intermediates when their concentration exceeds the capacity of the proteasome and molecular chaperones.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Aging
  • Amyotrophic Lateral Sclerosis / diagnosis
  • Amyotrophic Lateral Sclerosis / genetics*
  • Amyotrophic Lateral Sclerosis / metabolism
  • Animals
  • COS Cells
  • Chlorocebus aethiops
  • Disease Progression
  • HSP40 Heat-Shock Proteins / metabolism
  • HSP70 Heat-Shock Proteins / metabolism*
  • Humans
  • Mice
  • Mice, Transgenic
  • Mutation
  • Proteasome Endopeptidase Complex / metabolism*
  • Proteasome Inhibitors
  • Protein Folding
  • Sodium Dodecyl Sulfate / chemistry
  • Solubility
  • Superoxide Dismutase / chemistry*
  • Superoxide Dismutase / genetics*
  • Superoxide Dismutase-1


  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • Proteasome Inhibitors
  • SOD1 protein, human
  • Sodium Dodecyl Sulfate
  • Sod1 protein, mouse
  • Superoxide Dismutase
  • Superoxide Dismutase-1
  • Proteasome Endopeptidase Complex