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Involvement of FAN in TNF-induced apoptosis

B Ségui1, O Cuvillier, S Adam-Klages

  • 1Institut National de la Santé et de la Recherche Médicale U466, Centre Hospitalier Universitaire Rangueil, Toulouse, France.

The Journal of Clinical Investigation
|July 4, 2001
PubMed

Insights

The adapter protein FAN is crucial for tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis by mediating ceramide generation. FAN knockout cells resist TNF-alpha toxicity, highlighting its essential role in TNF-alpha signaling pathways.

Area of Science:

  • Cellular Biology
  • Immunology
  • Molecular Biology

Background:

  • Tumor necrosis factor-alpha (TNF-alpha) is a cytokine that triggers various signaling pathways involved in cell death and inflammation.
  • The precise mechanisms of TNF-alpha receptor signaling, particularly concerning membrane-proximal domains and associated proteins, remain incompletely understood.
  • The adapter protein FAN (factor associated with neutral SMase activation) has been implicated in TNF-alpha signaling, but its specific role in cytotoxicity requires further elucidation.

Purpose of the Study:

  • To investigate the role of the adapter protein FAN and its associated signaling domain in TNF-alpha-induced cytotoxicity.
  • To determine whether FAN is essential for TNF-alpha-mediated ceramide generation and apoptosis induction.
  • To clarify the specific contribution of FAN to TNF-alpha signaling pathways.

Main Methods:

  • Stable expression of a dominant-negative FAN mutant in human fibroblasts.
  • Assessment of TNF-alpha-induced ceramide generation via sphingomyelin hydrolysis.
  • Analysis of caspase processing and apoptosis induction.
  • Evaluation of cytotoxic responses to daunorubicin and exogenous ceramide.
  • Examination of TNF-alpha-induced p42/p44 MAPK activation and CD54 expression.
  • Utilizing fibroblasts from FAN-knockout mice.

Main Results:

  • Dominant-negative FAN expression inhibited TNF-alpha-induced ceramide generation and caspase processing, significantly reducing TNF-alpha-triggered apoptosis.
  • Cytotoxicity induced by daunorubicin and exogenous ceramide was not affected by FAN manipulation.
  • TNF-alpha-induced p42/p44 MAPK activation and CD54 expression remained unaltered.
  • Fibroblasts from FAN-knockout mice exhibited resistance to TNF-alpha toxicity.

Conclusions:

  • The adapter protein FAN plays a critical and previously unrecognized role in mediating TNF-alpha-induced apoptosis.
  • FAN is essential for TNF-alpha-triggered ceramide generation, a key event in the apoptotic signaling pathway.
  • FAN's function in TNF-alpha-induced cell death is specific and does not impact other TNF-alpha-mediated responses or general cytotoxicity.

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