F-actin binding regions on the androgen receptor and huntingtin increase aggregation and alter aggregate characteristics

PLoS One. 2010 Feb 4;5(2):e9053. doi: 10.1371/journal.pone.0009053.

Abstract

Protein aggregation is associated with neurodegeneration. Polyglutamine expansion diseases such as spinobulbar muscular atrophy and Huntington disease feature proteins that are destabilized by an expanded polyglutamine tract in their N-termini. It has previously been reported that intracellular aggregation of these target proteins, the androgen receptor (AR) and huntingtin (Htt), is modulated by actin-regulatory pathways. Sequences that flank the polyglutamine tract of AR and Htt might influence protein aggregation and toxicity through protein-protein interactions, but this has not been studied in detail. Here we have evaluated an N-terminal 127 amino acid fragment of AR and Htt exon 1. The first 50 amino acids of ARN127 and the first 14 amino acids of Htt exon 1 mediate binding to filamentous actin in vitro. Deletion of these actin-binding regions renders the polyglutamine-expanded forms of ARN127 and Htt exon 1 less aggregation-prone, and increases the SDS-solubility of aggregates that do form. These regions thus appear to alter the aggregation frequency and type of polyglutamine-induced aggregation. These findings highlight the importance of flanking sequences in determining the propensity of unstable proteins to misfold.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actins / metabolism*
  • Animals
  • Binding Sites / genetics
  • Blotting, Western
  • Cell Line
  • Exons / genetics
  • Fluorescence Resonance Energy Transfer
  • Humans
  • Huntingtin Protein
  • Inclusion Bodies / metabolism
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Confocal
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Protein Binding
  • Protein Conformation
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Deletion
  • Transfection
  • Trinucleotide Repeat Expansion / genetics

Substances

  • AR protein, human
  • Actins
  • HTT protein, human
  • Huntingtin Protein
  • Luminescent Proteins
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Receptors, Androgen
  • Recombinant Fusion Proteins