Protofibrils, pores, fibrils, and neurodegeneration: separating the responsible protein aggregates from the innocent bystanders

Annu Rev Neurosci. 2003;26:267-98. doi: 10.1146/annurev.neuro.26.010302.081142. Epub 2003 Apr 9.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amyloid beta-Peptides / metabolism
  • Amyotrophic Lateral Sclerosis / genetics
  • Amyotrophic Lateral Sclerosis / metabolism
  • Amyotrophic Lateral Sclerosis / physiopathology
  • Animals
  • Disease Models, Animal
  • Humans
  • In Vitro Techniques
  • Nerve Degeneration*
  • Nerve Tissue Proteins / metabolism
  • Neurodegenerative Diseases*
  • Neurofibrillary Tangles*
  • Plaque, Amyloid*
  • PrPSc Proteins / genetics
  • PrPSc Proteins / metabolism
  • PrPSc Proteins / pathogenicity
  • Prions / metabolism
  • Prions / pathogenicity
  • Superoxide Dismutase / metabolism
  • Superoxide Dismutase-1
  • Synucleins


  • Amyloid beta-Peptides
  • Nerve Tissue Proteins
  • PrPSc Proteins
  • Prions
  • SOD1 protein, human
  • Synucleins
  • Superoxide Dismutase
  • Superoxide Dismutase-1