Effect of torsinA on membrane proteins reveals a loss of function and a dominant-negative phenotype of the dystonia-associated DeltaE-torsinA mutant

Proc Natl Acad Sci U S A. 2004 Nov 2;101(44):15650-5. doi: 10.1073/pnas.0308088101. Epub 2004 Oct 25.

Abstract

Most cases of early-onset torsion dystonia (EOTD) are caused by a deletion of one glutamic acid in the carboxyl terminus of a protein named torsinA. The mutation causes the protein to aggregate in perinuclear inclusions as opposed to the endoplasmic reticulum localization of the wild-type protein. Although there is increasing evidence that dysfunction of the dopamine system is implicated in the development of EOTD, the biological function of torsinA and its relation to dopaminergic neurotransmission has remained unexplored. Here, we show that torsinA can regulate the cellular trafficking of the dopamine transporter, as well as other polytopic membrane-bound proteins, including G protein-coupled receptors, transporters, and ion channels. This effect was prevented by mutating the ATP-binding site in torsinA. The dystonia-associated torsinA deletion mutant (DeltaE-torsinA) did not have any effect on the cell surface distribution of polytopic membrane-associated proteins, suggesting that the mutation linked with EOTD results in a loss of function. However, a mutation in the ATP-binding site in DeltaE-torsinA reversed the aggregate phenotype associated with the mutant. Moreover, the deletion mutant acts as a dominant-negative of wild-type torsinA through a mechanism presumably involving association of wild-type and mutant torsinA. Taken together, our results provide evidence for a functional role for torsinA and a loss of function and a dominant-negative phenotype of the DeltaE-torsinA mutation. These properties may contribute to the autosomal dominant nature of the condition.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Motifs
  • Cell Line
  • Dopamine Plasma Membrane Transport Proteins
  • Dystonia Musculorum Deformans / etiology
  • Dystonia Musculorum Deformans / genetics
  • Dystonia Musculorum Deformans / physiopathology
  • Genes, Dominant
  • Humans
  • Macromolecular Substances
  • Membrane Glycoproteins / metabolism
  • Membrane Proteins / drug effects
  • Membrane Proteins / metabolism*
  • Membrane Transport Proteins / metabolism
  • Molecular Chaperones / genetics*
  • Molecular Chaperones / pharmacology
  • Molecular Chaperones / physiology*
  • Mutagenesis
  • Nerve Tissue Proteins / metabolism
  • Phenotype
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Sequence Deletion
  • Transfection

Substances

  • Dopamine Plasma Membrane Transport Proteins
  • Macromolecular Substances
  • Membrane Glycoproteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Molecular Chaperones
  • Nerve Tissue Proteins
  • Recombinant Proteins
  • TOR1A protein, human
  • Adenosine Triphosphate