Parkinson's disease-linked human PARK9/ATP13A2 maintains zinc homeostasis and promotes α-Synuclein externalization via exosomes

Hum Mol Genet. 2014 Jun 1;23(11):2816-33. doi: 10.1093/hmg/ddu099. Epub 2014 Mar 6.

Abstract

α-Synuclein plays a central causative role in Parkinson's disease (PD). Increased expression of the P-type ATPase ion pump PARK9/ATP13A2 suppresses α-Synuclein toxicity in primary neurons. Our data indicate that ATP13A2 encodes a zinc pump; neurospheres from a compound heterozygous ATP13A2(-/-) patient and ATP13A2 knockdown cells are sensitive to zinc, whereas ATP13A2 over-expression in primary neurons confers zinc resistance. Reduced ATP13A2 expression significantly decreased vesicular zinc levels, indicating ATP13A2 facilitates transport of zinc into membrane-bound compartments or vesicles. Endogenous ATP13A2 localized to multi-vesicular bodies (MVBs), a late endosomal compartment located at the convergence point of the endosomal and autophagic pathways. Dysfunction in MVBs can cause a range of detrimental effects including lysosomal dysfunction and impaired delivery of endocytosed proteins/autophagy cargo to the lysosome, both of which have been observed in cells with reduced ATP13A2 function. MVBs also serve as the source of intra-luminal nanovesicles released extracellularly as exosomes that can contain a range of cargoes including α-Synuclein. Elevated ATP13A2 expression reduced intracellular α-Synuclein levels and increased α-Synuclein externalization in exosomes >3-fold whereas ATP13A2 knockdown decreased α-Synuclein externalization. An increased export of exosome-associated α-Synuclein may explain why surviving neurons of the substantia nigra pars compacta in sporadic PD patients were observed to over-express ATP13A2. We propose ATP13A2's modulation of zinc levels in MVBs can regulate the biogenesis of exosomes capable of containing α-Synuclein. Our data indicate that ATP13A2 is the first PD-associated gene involved in exosome biogenesis and indicates a potential neuroprotective role of exosomes in PD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy
  • Exosomes / genetics
  • Exosomes / metabolism*
  • Homeostasis
  • Humans
  • Neurons / enzymology
  • Neurons / metabolism
  • Parkinson Disease / enzymology*
  • Parkinson Disease / genetics
  • Parkinson Disease / metabolism
  • Proton-Translocating ATPases / genetics
  • Proton-Translocating ATPases / metabolism*
  • Zinc / metabolism*
  • alpha-Synuclein / genetics
  • alpha-Synuclein / metabolism*

Substances

  • ATP13A2 protein, human
  • alpha-Synuclein
  • Proton-Translocating ATPases
  • Zinc