Abstract
Members of the tumor necrosis factor (TNF) superfamily of receptors such as Fas/CD95 and the TNF-related apoptosis-inducing ligand (TRAIL) receptors DR4 and DR5 induce apoptosis by recruiting adaptor molecules and caspases. The central adaptor molecule for these receptors is a death domain-containing protein, FADD, which binds to the activated receptor via death domain-death domain interactions. Here, we show that in addition to the death domain, the C-terminal tails of DR4 and DR5 positively regulate FADD binding, caspase activation and apoptosis. In contrast, the corresponding region in the Fas receptor has the opposite effect and inhibits binding to the receptor death domain. Replacement of wild-type or mutant DR5 molecules into DR5-deficient BJAB cells indicates that some agonistic antibodies display an absolute requirement for the C-terminal tail for FADD binding and signaling while other antibodies can function in the absence of this mechanism. These data demonstrate that regions outside the death domains of DR4 and DR5 have opposite effects to that of Fas in regulating FADD recruitment and show that different death receptor agonists can use distinct molecular mechanisms to activate signaling from the same receptor.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing / agonists
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Adaptor Proteins, Signal Transducing / genetics
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Adaptor Proteins, Signal Transducing / metabolism*
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Animals
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Apoptosis
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Apoptosis Regulatory Proteins
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Binding Sites
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Caspases / metabolism
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Cell Line
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Fas-Associated Death Domain Protein
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Genetic Complementation Test
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HeLa Cells
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Humans
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In Vitro Techniques
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Jurkat Cells
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Membrane Glycoproteins / chemistry*
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism*
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Mice
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Models, Biological
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Mutagenesis, Site-Directed
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Protein Binding
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Protein Structure, Tertiary
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Signal Transduction
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TNF-Related Apoptosis-Inducing Ligand
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Tumor Necrosis Factor-alpha / chemistry*
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Tumor Necrosis Factor-alpha / genetics
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Tumor Necrosis Factor-alpha / metabolism*
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fas Receptor / chemistry*
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fas Receptor / genetics
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fas Receptor / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Apoptosis Regulatory Proteins
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FADD protein, human
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Fadd protein, mouse
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Fas-Associated Death Domain Protein
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Membrane Glycoproteins
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Recombinant Proteins
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TNF-Related Apoptosis-Inducing Ligand
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TNFSF10 protein, human
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Tnfsf10 protein, mouse
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Tumor Necrosis Factor-alpha
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fas Receptor
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Caspases