Lysosomal enzyme cathepsin D protects against alpha-synuclein aggregation and toxicity.

Academic Article

Abstract

  • α-synuclein (α-syn) is a main component of Lewy bodies (LB) that occur in many neurodegenerative diseases, including Parkinson's disease (PD), dementia with LB (DLB) and multi-system atrophy. α-syn mutations or amplifications are responsible for a subset of autosomal dominant familial PD cases, and overexpression causes neurodegeneration and motor disturbances in animals. To investigate mechanisms for α-syn accumulation and toxicity, we studied a mouse model of lysosomal enzyme cathepsin D (CD) deficiency, and found extensive accumulation of endogenous α-syn in neurons without overabundance of α-syn mRNA. In addition to impaired macroautophagy, CD deficiency reduced proteasome activity, suggesting an essential role for lysosomal CD function in regulating multiple proteolytic pathways that are important for α-syn metabolism. Conversely, CD overexpression reduces α-syn aggregation and is neuroprotective against α-syn overexpression-induced cell death in vitro. In a C. elegans model, CD deficiency exacerbates α-syn accumulation while its overexpression is protective against α-syn-induced dopaminergic neurodegeneration. Mutated CD with diminished enzymatic activity or overexpression of cathepsins B (CB) or L (CL) is not protective in the worm model, indicating a unique requirement for enzymatically active CD. Our data identify a conserved CD function in α-syn degradation and identify CD as a novel target for LB disease therapeutics.
  • Published In

  • Molecular Brain  Journal
  • Keywords

  • Animals, Caenorhabditis elegans, Caspase 3, Cathepsin D, Cell Line, Tumor, Humans, Lysosomes, Mice, Mice, Inbred C57BL, Neurons, Neuroprotective Agents, Phagosomes, Point Mutation, Proteasome Endopeptidase Complex, Protein Structure, Quaternary, RNA, Messenger, Up-Regulation, alpha-Synuclein
  • Digital Object Identifier (doi)

    Author List

  • Qiao L; Hamamichi S; Caldwell KA; Caldwell GA; Yacoubian TA; Wilson S; Xie Z-L; Speake LD; Parks R; Crabtree D
  • Start Page

  • 17
  • Volume

  • 1