alpha-synuclein degradation by autophagic pathways: a potential key to Parkinson's disease pathogenesis

Autophagy. 2008 Oct;4(7):917-9. doi: 10.4161/auto.6685. Epub 2008 Oct 26.

Abstract

The neuronal protein alpha-synuclein is thought to be central in the pathogenesis of Parkinson's disease (PD). Excessive wild type alpha-synuclein levels can lead to PD in select familial cases and alpha-synuclein protein accumulation occurs in sporadic PD. Therefore, elucidation of the mechanisms that control alpha-synuclein levels is critical for PD pathogenesis and potential therapeutics. The subject of alpha-synuclein degradation has been controversial. Previous work shows that, in an assay with isolated liver lysosomes, purified wild type alpha-synuclein is degraded by the process of chaperone-mediated autophagy (CMA). Whether this actually occurs in a cellular context has been unclear. In our most recent work, we find that wild type alpha-synuclein, but not the closely related protein beta-synuclein, is indeed degraded by CMA in neuronal cells, including primary postnatal ventral midbrain neurons. Macroautophagy, but not the proteasome, also contributes to alpha-synuclein degradation. Therefore, two separate lysosomal pathways, CMA and macroautophagy, degrade wild type alpha-synuclein in neuronal cells. It is hypothesized that impairment of either of these two pathways, or of more general lysosomal function, may be an initiating factor in alpha-synuclein accumulation and sporadic PD pathogenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy*
  • Humans
  • Lysosomal-Associated Membrane Protein 2 / genetics
  • Lysosomal-Associated Membrane Protein 2 / metabolism
  • Lysosomes / metabolism
  • Molecular Chaperones / metabolism
  • Neurons / metabolism*
  • Parkinson Disease / etiology*
  • Parkinson Disease / metabolism
  • Rats
  • alpha-Synuclein / metabolism*

Substances

  • Lysosomal-Associated Membrane Protein 2
  • Molecular Chaperones
  • alpha-Synuclein