14-3-3 protein interacts with Huntingtin-associated protein 1 and regulates its trafficking

J Biol Chem. 2007 Feb 16;282(7):4748-56. doi: 10.1074/jbc.M609057200. Epub 2006 Dec 13.


HAP1 (Huntingtin-associated protein 1) consists of two alternately spliced isoforms (HAP1A and HAP1B, which have unique C-terminal sequences) and participates in intracellular trafficking. The C terminus of HAP1A is phosphorylated, and this phosphorylation was found to decrease the association of HAP1A with kinesin light chain, a protein involved in anterograde transport in cells. It remains unclear how this phosphorylation functions to regulate the association of HAP1 with trafficking proteins. Using the yeast two-hybrid system, we found that HAP1 also interacts with 14-3-3 proteins, which are involved in the assembly of protein complexes and the regulation of protein trafficking. The interaction of HAP1 with 14-3-3 is confirmed by their immunoprecipitation and colocalization in mouse brain. Moreover, this interaction is specific to HAP1A and is increased by the phosphorylation of the C terminus of HAP1A. We also found that expression of 14-3-3 decreases the association of HAP1A with kinesin light chain. As a result, there is less HAP1A distributed in neurite tips of PC12 cells that overexpress 14-3-3. Also, overexpression of 14-3-3 reduces the effect of HAP1A in promoting neurite outgrowth of PC12 cells. We propose that the phosphorylation-dependent interaction of HAP1A with 14-3-3 regulates HAP1 function by influencing its association with kinesin light chain and trafficking in neuronal processes.

Publication types

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

MeSH terms

  • 14-3-3 Proteins / genetics
  • 14-3-3 Proteins / metabolism*
  • Alternative Splicing / physiology
  • Animals
  • Brain / metabolism
  • Gene Expression
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Neurites / metabolism*
  • PC12 Cells
  • Phosphorylation
  • Protein Binding / physiology
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Processing, Post-Translational / physiology*
  • Protein Transport / physiology
  • Rats
  • Two-Hybrid System Techniques


  • 14-3-3 Proteins
  • Hap1 protein, mouse
  • Hap1 protein, rat
  • Microtubule-Associated Proteins
  • Multiprotein Complexes
  • Nerve Tissue Proteins
  • Protein Isoforms
  • kinesin light-chain proteins