<p>Death ligands, including FAS ligand (FASL) and tumor necrosis factor (TNF), trigger apoptosis by promoting caspase-8 dimerization and activation. Impaired FAS signaling causes unconventional lymphocytes to accumulate, resulting in lymphadenopathy. Although autoprocessing of caspase-8 is considered important for apoptosis, autoprocessing-deficient <i>Casp8</i><sup><i>D387A/D387A</i></sup> mice do not develop lymphadenopathy. We show that this is because heterodimers of caspase-8 D387A and cFLIP, besides suppressing MLKL-driven necroptosis, can also induce apoptosis. Interestingly, caspase-8 D387A elicited MLKL- and caspase-1-independent intestinal atrophy and perinatal lethality in mice lacking cFLIP. Caspase-8 D387A interacted with FADD and RIPK1 in the intestine, where there was aberrant cleavage of N4BP1 and caspase-3, plus enhanced NF-κB signaling. Eliminating FADD, the adaptor protein that promotes caspase-8 oligomerization, prevented this perinatal lethality. Collectively, our results suggest that cFLIP forms heterodimers with caspase-8 D387A to promote apoptosis in some contexts, while limiting the activity of caspase-8 D387A homodimers in others.</p>

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cFLIP suppresses caspase-1- and MLKL-independent perinatal lethality driven by auto-processing impaired caspase-8 D387A

  • Kim Newton,
  • Katherine E. Wickliffe,
  • Allie Maltzman,
  • Debra L. Dugger,
  • Juan Reyes Jr,
  • Natasha Bacarro,
  • Søren Warming,
  • Neha Rohatgi,
  • Rohit Reja,
  • Joshua D. Webster,
  • Vishva M. Dixit

摘要

Death ligands, including FAS ligand (FASL) and tumor necrosis factor (TNF), trigger apoptosis by promoting caspase-8 dimerization and activation. Impaired FAS signaling causes unconventional lymphocytes to accumulate, resulting in lymphadenopathy. Although autoprocessing of caspase-8 is considered important for apoptosis, autoprocessing-deficient Casp8D387A/D387A mice do not develop lymphadenopathy. We show that this is because heterodimers of caspase-8 D387A and cFLIP, besides suppressing MLKL-driven necroptosis, can also induce apoptosis. Interestingly, caspase-8 D387A elicited MLKL- and caspase-1-independent intestinal atrophy and perinatal lethality in mice lacking cFLIP. Caspase-8 D387A interacted with FADD and RIPK1 in the intestine, where there was aberrant cleavage of N4BP1 and caspase-3, plus enhanced NF-κB signaling. Eliminating FADD, the adaptor protein that promotes caspase-8 oligomerization, prevented this perinatal lethality. Collectively, our results suggest that cFLIP forms heterodimers with caspase-8 D387A to promote apoptosis in some contexts, while limiting the activity of caspase-8 D387A homodimers in others.