Protofibrils, pores, fibrils, and neurodegeneration: separating the responsible protein aggregates from the innocent bystanders.
Many neurodegenerative diseases, including Alzheimer's and Parkinson's and the transmissible spongiform encephalopathies (prion diseases), are characterized at autopsy by neuronal loss and protein aggregates that are typically fibrillar. A convergence of evidence strongly suggests that protein aggregation is neurotoxic and not a product of cell death. However, the identity of the neurotoxic aggregate and the mechanism by which it disables and eventually kills a neuron are unknown. Both biophysical studies aimed at elucidating the precise mechanism of in vitro aggregation and animal modeling studies support the emerging notion that an ordered prefibrillar oligomer, or protofibril, may be responsible for cell death and that the fibrillar form that is typically observed at autopsy may actually be neuroprotective. A subpopulation of protofibrils may function as pathogenic amyloid pores. An analogous mechanism may explain the neurotoxicity of the prion protein; recent data demonstrates that the disease-associated, infectious form of the prion protein differs from the neurotoxic species. This review focuses on recent experimental studies aimed at identification and characterization of the neurotoxic protein aggregates.
Caughey
Byron
B
NIAID, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana, USA. bcaughey@niaid.nih.gov
Lansbury
Peter T
PT
D016229:Amyloid beta-Peptides / Q000378:metabolism; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D004195:Disease Models, Animal; D006801:Humans; D066298:In Vitro Techniques; D009410:Nerve Degeneration; D009419:Nerve Tissue Proteins / Q000378:metabolism; D019636:Neurodegenerative Diseases; D016874:Neurofibrillary Tangles; D058225:Plaque, Amyloid; D018620:PrPSc Proteins / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D011328:Prions / Q000378:metabolism / Q000472:pathogenicity; D013482:Superoxide Dismutase / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D051843:Synucleins
D016229:Amyloid beta-Peptides; D009419:Nerve Tissue Proteins; D018620:PrPSc Proteins; D011328:Prions; C000606290:SOD1 protein, human; D051843:Synucleins; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1