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Keywords:

  • misfolding;
  • neurodegenerative disease;
  • Parkinson’s disease;
  • protein aggregation;
  • secretion

J. Neurochem. (2010) 113, 1263–1274.

Abstract

Parkinson’s disease is characterized by deposition of misfolded/aggregated α-synuclein proteins in multiple regions of the brain. Neurons can release α-synuclein; through this release, pathological forms of α-synuclein are propagated between neurons, and also cause neuroinflammation. In this study, we demonstrate that release of α-synuclein is consistently increased under various protein misfolding stress conditions in both neuroblastoma and primary neuron models. This release is mediated by a non-classical, endoplasmic reticulum (ER)/Golgi-independent exocytosis, and stress-induced release coincides with increased translocation of α-synuclein into vesicles. Both vesicle translocation and secretion were blocked by attachment of a highly stable, globular protein to α-synuclein, whereas forced protein misfolding resulted in an increase in both of these activities. Mass spectrometry analysis showed a higher degree of oxidative modification in secreted α-synuclein than in the cellular protein. Together, these results suggest that structurally abnormal, damaged α-synuclein proteins translocate preferentially into vesicles and are released from neuronal cells via exocytosis.