CD95 death-inducing signaling complex formation and internalization occur in lipid rafts of type I and type II cells

Eur J Immunol. 2004 Jul;34(7):1930-40. doi: 10.1002/eji.200324786.

Abstract

We investigated the membrane localization of CD95 in type I and type II cells, which differ in their ability to recruit and activate caspase-8. We found that CD95 was preferentially located in lipid rafts of type I cells, while it was present both in raft and non-raft plasma membrane sub-domains of type II cells. After stimulation, CD95 located in phospholipid-rich plasma membrane was recruited to lipid rafts in both types of cells. Similarly, CD95 cross-linking resulted in caspase-independent translocation of FADD/MORT1 and caspase-8 to the lipid rafts, which was prevented by a death domain-defective receptor. CD95 internalization was then rapid in type I and delayed in type II cells and showed a substantial correlation with the kinetics of Fas-associated death domain (FADD)and caspase-8 recruitment to lipid rafts. Finally, electron microscopy analysis showed that after CD95 stimulation lipid rafts aggregated in large clusters that were internalized in endosomal vesicles, where caspase-8 underwent massive processing. Taken together, our data demonstrate that CD95 death-inducing signaling complex formation and internalization in type I and type II cells occur in lipid rafts, which are a major site of caspase-8 activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / physiology*
  • Caspases / metabolism
  • Cell Line, Tumor
  • Cholesterol / metabolism
  • Death Domain Receptor Signaling Adaptor Proteins
  • Endocytosis*
  • Humans
  • Membrane Microdomains / metabolism*
  • Protein Binding
  • Protein Transport
  • Receptors, Tumor Necrosis Factor / metabolism
  • Signal Transduction*
  • T-Lymphocytes / cytology
  • T-Lymphocytes / metabolism
  • fas Receptor / metabolism*

Substances

  • Death Domain Receptor Signaling Adaptor Proteins
  • Receptors, Tumor Necrosis Factor
  • fas Receptor
  • Cholesterol
  • Caspases