Role of GD3-CLIPR-59 association in lymphoblastoid T cell apoptosis triggered by CD95/Fas

PLoS One. 2010 Jan 5;5(1):e8567. doi: 10.1371/journal.pone.0008567.

Abstract

We previously found that a directional movement of the raft component GD3 towards mitochondria, by its association with microtubules, was mandatory to late apoptogenic events triggered by CD95/Fas. Since CLIPR-59, CLIP-170-related protein, has recently been identified as a microtubule binding protein associated with lipid rafts, we analyzed the role of GD3-CLIPR-59 association in lymphoblastoid T cell apoptosis triggered by CD95/Fas. To test whether CLIPR-59 could play a role at the raft-microtubule junction, we performed a series of experiments by using immunoelectron microscopy, static or flow cytometry and biochemical analyses. We first assessed the presence of CLIPR-59 molecule in lymphoblastoid T cells (CEM). Then, we demonstrated that GD3-microtubule interaction occurs via CLIPR-59 and takes place at early time points after CD95/Fas ligation, preceding the association GD3-tubulin. GD3-CLIPR-59 association was demonstrated by fluorescence resonance energy transfer (FRET) analysis. The key role of CLIPR-59 in this dynamic process was clarified by the observation that silencing CLIPR-59 by siRNA affected the kinetics of GD3-tubulin association, spreading of GD3 towards mitochondria and apoptosis execution. We find that CLIPR-59 may act as a typical chaperone, allowing a prompt interaction between tubulin and the raft component GD3 during cell apoptosis triggered by CD95/Fas. On the basis of the suggested role of lipid rafts in conveying pro-apoptotic signals these results disclose new perspectives in the understanding of the mechanisms by which raft-mediated pro-apoptotic signals can directionally reach their target, i.e. the mitochondria, and trigger apoptosis execution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / immunology*
  • Apoptosis / physiology
  • Cell Line
  • Fluorescence Resonance Energy Transfer
  • Gangliosides / physiology*
  • Humans
  • Microscopy, Electron, Transmission
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / physiology*
  • T-Lymphocytes / cytology*
  • T-Lymphocytes / immunology
  • fas Receptor / immunology*

Substances

  • CLIP3 protein, human
  • Gangliosides
  • Microtubule-Associated Proteins
  • fas Receptor
  • ganglioside, GD3