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The death effector domain-associated factor plays distinct regulatory roles in the nucleus and cytoplasm
L Zheng1, O Schickling, M E Peter
1Laboratory of Immunology, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
Homophilic interactions of death effector domains (DEDs) are crucial for the signaling pathways of death receptor-mediated apoptosis. The machinery that regulates proper oligomerization and autoactivation of procaspase-8 and/or procaspase-10 during T lymphocyte activation determines whether the cells will undergo caspase-mediated apoptosis or proliferation. We screened a yeast two-hybrid library by using the DEDs contained in the prodomains of procaspase-8 and procaspase-10 and isolated a DED-associated factor (DEDAF) that interacts with several DED-containing proteins but does not itself contain a DED. DEDAF is highly conserved between human and mouse (98% amino acid identity) and is homologous to a nuclear regulatory protein YAF-2. DEDAF is expressed at the highest levels in lymphoid tissues and placenta. DEDAF interacts with FADD, procaspase-8, and procaspase-10 in the cytosol as well as with the DED-containing DNA-binding protein (DEDD) in the nucleus. At the cell membrane, DEDAF augmented the formation of CD95-FADD-caspase-8 complexes and enhanced death receptor- as well as DED-mediated apoptosis. In the nucleus, DEDAF caused the DEDD protein to relocalize from subnuclear structures to a diffuse distribution in the nucleoplasm. Our data therefore suggest that DEDAF may be involved in the regulation of both cytoplasmic and nuclear events of apoptosis.
Insights
Death effector domain-associated factor (DEDAF) regulates apoptosis by interacting with key proteins in both the cytoplasm and nucleus. This factor enhances death receptor signaling and influences caspase activation, impacting T cell fate.
Area of Science:
- Molecular Biology
- Cell Biology
- Immunology
Background:
- Death effector domains (DEDs) mediate homophilic interactions critical for death receptor-mediated apoptosis signaling.
- Procaspase-8 and procaspase-10 oligomerization during T lymphocyte activation dictates apoptosis or proliferation.
- Understanding regulators of these DED interactions is key to controlling cell death pathways.
Purpose of the Study:
- To identify novel proteins interacting with DEDs of procaspase-8 and procaspase-10.
- To characterize the function of a newly identified DED-associated factor (DEDAF) in apoptosis regulation.
- To investigate DEDAF's role in both cytoplasmic and nuclear cellular compartments.
Main Methods:
- Yeast two-hybrid screening using DEDs from procaspase-8 and procaspase-10 prodomains.
- Co-immunoprecipitation and cellular localization studies to confirm interactions and cellular distribution.
- Analysis of DEDAF's effect on death receptor complex formation and apoptosis induction.
Main Results:
- A novel protein, DED-associated factor (DEDAF), was identified, interacting with multiple DED-containing proteins.
- DEDAF, highly conserved and homologous to YAF-2, is expressed in lymphoid tissues and placenta.
- DEDAF promotes CD95-FADD-caspase-8 complex assembly, enhancing apoptosis, and alters nuclear DEDD protein localization.
Conclusions:
- DEDAF is a crucial regulator of apoptosis, acting in both the cytoplasm and nucleus.
- DEDAF enhances death receptor-mediated apoptosis by facilitating caspase-8 recruitment and activation.
- DEDAF's dual cytoplasmic and nuclear functions suggest a broad role in regulating cell death.