Ataxin-3 protein and RNA toxicity in spinocerebellar ataxia type 3: current insights and emerging therapeutic strategies

Mol Neurobiol. 2014 Jun;49(3):1513-31. doi: 10.1007/s12035-013-8596-2. Epub 2013 Nov 29.


Ataxin-3 is a ubiquitously expressed deubiqutinating enzyme with important functions in the proteasomal protein degradation pathway and regulation of transcription. The C-terminus of the ataxin-3 protein contains a polyglutamine (PolyQ) region that, when mutationally expanded to over 52 glutamines, causes the neurodegenerative disease spinocerebellar ataxia 3 (SCA3). In spite of extensive research, the molecular mechanisms underlying the cellular toxicity resulting from mutant ataxin-3 remain elusive and no preventive treatment is currently available. It has become clear over the last decade that the hallmark intracellular ataxin-3 aggregates are likely not the main toxic entity in SCA3. Instead, the soluble PolyQ containing fragments arising from proteolytic cleavage of ataxin-3 by caspases and calpains are now regarded to be of greater influence in pathogenesis. In addition, recent evidence suggests potential involvement of a RNA toxicity component in SCA3 and other PolyQ expansion disorders, increasing the pathogenic complexity. Herein, we review the functioning of ataxin-3 and the involvement of known protein and RNA toxicity mechanisms of mutant ataxin-3 that have been discovered, as well as future opportunities for therapeutic intervention.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Antioxidants / metabolism
  • Antioxidants / therapeutic use
  • Ataxin-3
  • Humans
  • Machado-Joseph Disease / genetics*
  • Machado-Joseph Disease / metabolism
  • Machado-Joseph Disease / therapy*
  • Nerve Tissue Proteins / physiology*
  • Nuclear Proteins / physiology*
  • Peptides / genetics
  • Peptides / metabolism
  • RNA / genetics
  • RNA / toxicity*
  • Repressor Proteins / physiology*


  • Antioxidants
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Peptides
  • Repressor Proteins
  • polyglutamine
  • RNA
  • ATXN3 protein, human
  • Ataxin-3