Structural properties and neuronal toxicity of amyotrophic lateral sclerosis-associated Cu/Zn superoxide dismutase 1 aggregates.
The appearance of protein aggregates is a characteristic of protein misfolding disorders including familial amyotrophic lateral sclerosis, a neurodegenerative disease caused by inherited mutations in Cu/Zn superoxide dismutase 1 (SOD1). Here, we use live cell imaging of neuronal and nonneuronal cells to show that SOD1 mutants (G85R and G93A) form an aggregate structure consisting of immobile scaffolds, through which noninteracting cellular proteins can diffuse. Hsp70 transiently interacts, in a chaperone activity-dependent manner, with these mutant SOD1 aggregate structures. In contrast, the proteasome is sequestered within the aggregate structure, an event associated with decreased degradation of a proteasomal substrate. Through the use of time-lapse microscopy of individual cells, we show that nearly all (90%) aggregate-containing cells express higher levels of mutant SOD1 and died within 48 h, whereas 70% of cells expressing a soluble mutant SOD1 survived. Our results demonstrate that SOD1 G85R and G93A mutants form a distinct class of aggregate structures in cells destined for neuronal cell death.
Matsumoto
Gen
G
Department of Biochemistry, Molecular Biology and Cell Biology, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL 60208, USA.
Stojanovic
Aleksandar
A
Holmberg
Carina I
CI
Kim
Soojin
S
Morimoto
Richard I
RI
D019943:Amino Acid Substitution; D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology* / Q000235:genetics; D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances / Q000378:metabolism; D009154:Mutation; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016716:PC12 Cells; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D051381:Rats; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*
D018840:HSP70 Heat-Shock Proteins; D046911:Macromolecular Substances; C109415:SOD1 G93A protein; D013482:Superoxide Dismutase; D046988:Proteasome Endopeptidase Complex