SIMPLE/LITAF expression induces the translocation of the ubiquitin ligase itch towards the lysosomal compartments

PLoS One. 2011 Feb 4;6(2):e16873. doi: 10.1371/journal.pone.0016873.

Abstract

LITAF is a small cellular protein with an unknown function. The C-terminus of LITAF contains a highly conserved domain termed the SIMPLE-like domain (SLD), while the N-terminus contains two PPXY motifs that mediate protein-protein interactions with WW-domain containing proteins. LITAF also harbors two endosome/lysosome targeting sequences at its C-terminus, but there has been conflicting reports regarding its intracellular localization. Here, we demonstrate that LITAF is localized to the late endosome/lysosomal compartment in a variety of cell lines. We also show that Itch, a WW-domain containing protein, and LITAF strongly interact and that this interaction depends on the two PPXY motifs in the N-terminus of LITAF. Interestingly, co-expression of LITAF with Itch induces major changes in Itch intracellular localization, bringing Itch from the trans-Golgi network to lysosomes. We show that this re-localization is dependent upon the interaction with the PPXY sequences of LITAF, since disruption of these binding motifs completely abrogates Itch re-localization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Newborn
  • Cell Compartmentation
  • Cell Line
  • Chlorocebus aethiops
  • Humans
  • Lysosomes / metabolism*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / physiology
  • Protein Binding
  • Protein Interaction Domains and Motifs / genetics
  • Protein Interaction Domains and Motifs / physiology
  • Protein Transport / genetics
  • Repressor Proteins / metabolism*
  • Transcription Factors / chemistry
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Transcription Factors / physiology
  • Ubiquitin-Protein Ligases / metabolism*
  • Up-Regulation / physiology

Substances

  • LITAF protein, human
  • Nuclear Proteins
  • Repressor Proteins
  • Transcription Factors
  • ITCH protein, human
  • Ubiquitin-Protein Ligases