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Competitive control of independent programs of tumor necrosis factor receptor-induced cell death by TRADD and RIP1

Lixin Zheng1, Nicolas Bidere, David Staudt

  • 1Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, NIH, 9000 Rockville Pike, 10/11D09, Bethesda, MD 20892, USA. lzheng@niaid.nih.gov

Molecular and Cellular Biology
|April 14, 2006
PubMed

Insights

Tumor necrosis factor receptor 1 (TNFR1) signaling involves TRADD and RIP1 proteins. These proteins compete to determine cell fate, initiating either apoptosis or necrosis via distinct pathways.

Area of Science:

  • Cellular biology
  • Immunology
  • Molecular signaling

Background:

  • Tumor necrosis factor receptor 1 (TNFR1) triggers diverse cellular outcomes, including apoptosis, necrosis, and NF-kappaB activation.
  • The TNFR-associated death domain (TRADD) protein is hypothesized as a key mediator of TNFR1 signaling.
  • Lack of TRADD-deficient cells hindered direct analysis of its role in mature immune cells.

Purpose of the Study:

  • To investigate the specific roles of TRADD and RIP1 in TNFR1-mediated cellular responses.
  • To elucidate the mechanism by which TNFR1 signaling pathways diverge to induce distinct cell death programs.

Main Methods:

  • Small interfering RNA (siRNA) was used to silence TRADD expression in cells.
  • Analysis of TNFR1-initiated signaling pathways, including NF-kappaB activation, apoptosis, and necrosis.
  • Investigated the competitive recruitment of TRADD and RIP1 to the TNFR1 signaling complex.

Main Results:

  • TRADD is essential for TNFR1-induced NF-kappaB activation and caspase-8-dependent apoptosis.
  • TRADD is dispensable for TNFR1-initiated, RIP1-dependent necrotic cell death.
  • TRADD and RIP1 compete for binding to TNFR1, directing distinct downstream signaling events.

Conclusions:

  • TNFR1 signaling diverges at the level of TRADD and RIP1 recruitment.
  • These two proteins act as competing transducers, dictating cell fate decisions.
  • TRADD and RIP1 independently control NF-kappaB activation, apoptosis, and nonapoptotic cell death pathways.

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