Loss of RAD-23 Protects Against Models of Motor Neuron Disease by Enhancing Mutant Protein Clearance

J Neurosci. 2015 Oct 21;35(42):14286-306. doi: 10.1523/JNEUROSCI.0642-15.2015.


Misfolded proteins accumulate and aggregate in neurodegenerative disease. The existence of these deposits reflects a derangement in the protein homeostasis machinery. Using a candidate gene screen, we report that loss of RAD-23 protects against the toxicity of proteins known to aggregate in amyotrophic lateral sclerosis. Loss of RAD-23 suppresses the locomotor deficit of Caenorhabditis elegans engineered to express mutTDP-43 or mutSOD1 and also protects against aging and proteotoxic insults. Knockdown of RAD-23 is further neuroprotective against the toxicity of SOD1 and TDP-43 expression in mammalian neurons. Biochemical investigation indicates that RAD-23 modifies mutTDP-43 and mutSOD1 abundance, solubility, and turnover in association with altering the ubiquitination status of these substrates. In human amyotrophic lateral sclerosis spinal cord, we find that RAD-23 abundance is increased and RAD-23 is mislocalized within motor neurons. We propose a novel pathophysiological function for RAD-23 in the stabilization of mutated proteins that cause neurodegeneration.

Significance statement: In this work, we identify RAD-23, a component of the protein homeostasis network and nucleotide excision repair pathway, as a modifier of the toxicity of two disease-causing, misfolding-prone proteins, SOD1 and TDP-43. Reducing the abundance of RAD-23 accelerates the degradation of mutant SOD1 and TDP-43 and reduces the cellular content of the toxic species. The existence of endogenous proteins that act as "anti-chaperones" uncovers new and general targets for therapeutic intervention.

Keywords: ALS; RAD-23; aging; motor neuron disease; neurodegeneration; proteotoxicity.

Publication types

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

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Animals, Newborn
  • Caenorhabditis elegans
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cells, Cultured
  • DNA-Binding Proteins / metabolism
  • Disease Models, Animal
  • Gene Expression Regulation / genetics
  • Genotype
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Male
  • Mice
  • Motor Activity / genetics
  • Motor Neuron Disease / genetics*
  • Mutation / genetics*
  • Photobleaching
  • RNA Interference / physiology*
  • Rats
  • Rats, Sprague-Dawley


  • Caenorhabditis elegans Proteins
  • DNA-Binding Proteins
  • Rad-23 protein, C elegans
  • Green Fluorescent Proteins