Affinage

CRADD

Death domain-containing protein CRADD · UniProt P78560

Length
199 aa
Mass
22.7 kDa
Annotated
2026-04-28
31 papers in source corpus 20 papers cited in narrative 20 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CRADD (RAIDD) is a bipartite death-fold adaptor protein that bridges upstream death-domain signaling to caspase-2 activation and additionally functions as a negative regulator of NF-κB signaling. Its C-terminal death domain (DD) engages PIDD via DD:DD interaction to nucleate the PIDDosome, wherein PIDD binding opens RAIDD's autoinhibited conformation and permits its N-terminal CARD to recruit and activate caspase-2 through homophilic CARD:CARD interaction; this ordered assembly drives proximity-induced caspase-2 activation in stress-induced apoptosis, including trophic factor withdrawal in neurons (PMID:8985253, PMID:16183742, PMID:24064063, PMID:22515271). CRADD also suppresses NF-κB-dependent inflammatory signaling by engaging BCL10 through its CARD to disrupt CARMA1/CARMA3 signalosomes in T cells and endothelial cells, and serves as a scaffold coordinating IKKε–IRF7 interaction for type I interferon production (PMID:22323537, PMID:24958727, PMID:27606466). Homozygous loss-of-function mutations in the CRADD death domain cause thin lissencephaly in humans by abolishing caspase-2 activation and reducing developmental neuronal apoptosis, while Cradd-knockout mice display megalencephaly and seizures (PMID:27773430, PMID:30281648).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 1997 High

    The fundamental question of how RIP kinase signaling connects to caspase activation was answered by the discovery that CRADD/RAIDD is a bipartite adaptor whose DD binds RIP and whose CARD binds caspase-2, establishing the first molecular bridge between death-domain signaling and the caspase cascade.

    Evidence Yeast two-hybrid, co-immunoprecipitation, domain mapping, and mutagenesis in two independent studies

    PMID:8985253 PMID:9044836

    Open questions at the time
    • Whether CRADD mediates RIP-dependent caspase activation in vivo was not tested
    • Upstream signals triggering the RIP–CRADD–caspase-2 axis were unknown
  2. 1998 High

    How the CARD of RAIDD physically recognizes caspase-2 was resolved by solving the NMR structure, revealing a six-helix bundle with complementary charged patches that mediate CARD:CARD interaction.

    Evidence NMR solution structure with mutagenesis of acidic and basic surface patches disrupting caspase-2 binding

    PMID:9695946

    Open questions at the time
    • Structure of the full-length RAIDD including the DD was not determined
    • No structure of the CARD:CARD complex itself
  3. 2000 Medium

    The question of where RAIDD acts in the cell was addressed by showing it is predominantly cytoplasmic, can form CARD-dependent filamentous oligomers, and is partially recruited to the nucleus by caspase-2, suggesting intramolecular autoinhibition regulates its oligomerization.

    Evidence Subcellular fractionation, immunofluorescence, and live-cell imaging of CARD-only versus full-length constructs

    PMID:10713730

    Open questions at the time
    • Whether nuclear recruitment is physiologically relevant was unclear
    • Autoinhibition was inferred but not structurally resolved
  4. 2005 High

    Genetic epistasis in RAIDD-knockout and caspase-2-knockout MEFs established that RAIDD is absolutely required for PIDD-induced apoptosis, placing it as the essential adaptor between PIDD and caspase-2 in the PIDDosome.

    Evidence RAIDD−/− and caspase-2−/− mouse embryonic fibroblasts with PIDD overexpression and caspase activity assays

    PMID:16183742

    Open questions at the time
    • Whether endogenous PIDD-dependent stimuli require RAIDD in vivo remained untested
    • The stoichiometry and assembly order of the PIDDosome were unknown
  5. 2006 High

    The crystal structure of the RAIDD DD at 2.0 Å and functional studies in neurons together defined the structural basis for PIDDosome DD:DD interaction and showed that RAIDD activates caspase-2-dependent apoptosis specifically in trophic factor withdrawal but not DNA-damage pathways.

    Evidence X-ray crystallography of RAIDD DD; siRNA knockdown in PC12 cells and sympathetic neurons with pathway-specific stimuli

    PMID:14765136 PMID:15947787 PMID:16434054

    Open questions at the time
    • Structure of the RAIDD DD:PIDD DD complex was not yet solved
    • The identity of upstream signals channeling through RAIDD in trophic deprivation was unknown
  6. 2010 Medium

    Biochemical reconstitution revealed that PIDDosome assembly is ordered and governed by critical interface residues (RAIDD R147, PIDD Y814), with dominant-negative mutants blocking new assembly but unable to disassemble preformed complexes.

    Evidence Recombinant protein reconstitution, mutagenesis, and dominant-negative biochemical assays

    PMID:17329820 PMID:20406701

    Open questions at the time
    • The precise stoichiometry of the PIDDosome was not fully resolved
    • Whether the same assembly rules apply in living cells was untested
  7. 2012 High

    Two distinct non-apoptotic roles for CRADD were uncovered: in neurons, RAIDD activates caspase-2 independently of PIDD during NGF deprivation and Aβ-induced death; in T cells, CRADD suppresses NF-κB by engaging BCL10 through its CARD to disrupt CARMA1-BCL10 signalosome formation.

    Evidence RAIDD−/− and PIDD−/− neurons with co-IP and caspase-2 activity assays; CRADD−/− primary T cells with cytokine measurement and BCL10 co-IP

    PMID:22323537 PMID:22515271

    Open questions at the time
    • How CRADD is recruited to the BCL10–CARMA1 complex is unknown
    • Whether PIDD-independent caspase-2 activation uses an alternative DD partner was not identified
  8. 2013 Medium

    The ordered assembly mechanism of the PIDDosome was defined: PIDD DD binding opens the autoinhibited full-length RAIDD, which then solubilizes and recruits the otherwise insoluble caspase-2 CARD, establishing sequential conformational gating.

    Evidence Recombinant reconstitution of all three DD superfamily domains with solubility and binding assays

    PMID:24064063

    Open questions at the time
    • No structural snapshot of the conformational change in full-length RAIDD upon PIDD binding
    • Kinetics of the conformational switch in cells remain uncharacterized
  9. 2014 Medium

    CRADD's negative regulation of NF-κB was extended to endothelial cells (CARMA3 signalosome), and HDAC1 was identified as a direct transcriptional repressor of CRADD, linking epigenetic regulation to the CRADD–caspase-2 apoptotic axis in gastric cancer.

    Evidence CRADD−/− endothelial cells with permeability/cytokine assays and recombinant CRADD rescue; ChIP showing HDAC1 at the CRADD promoter with siRNA and HDAC inhibitor validation

    PMID:24958727 PMID:25360218

    Open questions at the time
    • Whether HDAC1-mediated CRADD repression is relevant beyond gastric cancer is unknown
    • The transcription factor through which HDAC1 represses CRADD was not identified
  10. 2016 High

    CRADD DD mutations (G128R, F164C, R170C, R170H) were identified as causal for thin lissencephaly by abolishing caspase-2 activation without disrupting protein–protein interactions in co-IP, and peptide inhibitors targeting the DD helix-3 interface validated this surface as critical for PIDDosome function; CRADD was also shown to scaffold IKKε–IRF7 for type I interferon production.

    Evidence Patient mutation functional characterization with co-IP and caspase-2 assays; Cradd−/− mice showing megalencephaly; TAT-peptide inhibition of PIDDosome in vitro and in neuronal cells; co-IP of RAIDD with IRF7 and IKKε with luciferase reporter

    PMID:27502430 PMID:27606466 PMID:27773430

    Open questions at the time
    • How DD mutations abolish caspase-2 activation while preserving binary interactions is mechanistically unclear
    • The role of CRADD in IFN signaling was shown only in overexpression/reporter systems
  11. 2018 Medium

    The molecular mechanism of lissencephaly-causing mutations was clarified: TLIS DD mutations specifically disrupt the DD:DD interaction with PIDD, resolving the apparent paradox of preserved co-IP but lost caspase-2 activation.

    Evidence Systematic mutagenesis and pulldown/co-IP of DD mutants with PIDD DD

    PMID:30281648

    Open questions at the time
    • No high-resolution structure of mutant DD:PIDD DD complexes
    • Whether residual PIDDosome assembly occurs in vivo with these mutations is untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include the identity of the upstream signal or DD partner that activates RAIDD–caspase-2 independently of PIDD in neurons, the structural basis of RAIDD autoinhibition and its conformational opening, and the physiological relevance of CRADD's NF-κB and IFN regulatory functions in vivo.
  • No PIDD-independent DD partner for RAIDD has been identified in neurons
  • No structure of full-length autoinhibited RAIDD exists
  • In vivo validation of CRADD's role in IFN signaling is lacking

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 5 GO:0098772 molecular function regulator activity 2
Localization
GO:0005634 nucleus 1 GO:0005829 cytosol 1
Pathway
R-HSA-5357801 Programmed Cell Death 7 R-HSA-162582 Signal Transduction 3 R-HSA-168256 Immune System 2 R-HSA-1266738 Developmental Biology 1
Partners
BCL10CASP2IKBKEIRF7PIDD1RIPK1
Complex memberships
PIDDosome (PIDD DD:RAIDD DD:caspase-2 CARD)RAIDD-caspase-2 complex (PIDD-independent)

Evidence

Reading pass · 20 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1997 RAIDD/CRADD was identified as a bipartite adaptor molecule with a C-terminal death domain (DD) that binds to the DD of RIP (a serine/threonine kinase), and an N-terminal CARD homologous to the prodomain of ICE/CED-3 family members (caspase-2/ICH-1 and CED-3) that mediates homophilic binding to these caspases, directly linking RIP signaling to caspase activation. Yeast two-hybrid, co-immunoprecipitation, domain mapping, mutagenesis of N-terminal CARD equivalent to ced-3 inactivating mutations Nature High 8985253
1997 CRADD was independently shown to have an NH2-terminal caspase homology domain (CARD) that interacts with caspase-2 and a COOH-terminal death domain that interacts with RIP, constituting a dual-domain adaptor that induces apoptosis. Co-immunoprecipitation, domain deletion constructs, apoptosis assays Cancer research High 9044836
1998 The NMR solution structure of the RAIDD CARD was solved, revealing six tightly packed helices in a topology homologous to the Fas death domain, with a basic and acidic patch on opposite sides that mediate CARD/CARD interaction with ICH-1/caspase-2; mutagenesis of these patches disrupted CARD/CARD binding. NMR structure determination, homology modeling, mutagenesis of surface residues Cell High 9695946
2000 Endogenous RAIDD is predominantly cytoplasmic with some nuclear localization; upon co-expression with caspase-2, a fraction of RAIDD is recruited to the nucleus. The RAIDD CARD mediates oligomerization into filamentous structures similar to death effector filaments (DEFs), and CARD-dependent colocalization of RAIDD and caspase-2 occurs at discrete subcellular structures. Intramolecular folding of RAIDD may regulate CARD oligomerization. Subcellular fractionation, immunofluorescence, co-transfection with deletion mutants, live-cell imaging of CARD-only constructs Cell death and differentiation Medium 10713730
2005 PIDD-induced apoptosis and growth suppression in embryonic fibroblasts depends on the adaptor protein RAIDD (genetic epistasis); PIDD-induced cell death is associated with early caspase-2 activation and later caspase-3 and -7 activation. Caspase-2 knockout cells are only partially resistant, while RAIDD knockout cells are fully resistant to PIDD-induced death. RAIDD-/- and caspase-2-/- mouse embryonic fibroblasts, genetic epistasis, caspase activity assays Proceedings of the National Academy of Sciences of the United States of America High 16183742
2006 Crystal structure of RAIDD DD was solved at 2.0 Å resolution, revealing structural features important for DD folding, dynamics, and PIDDosome assembly via DD:DD interaction with PIDD. X-ray crystallography at 2.0 Å resolution Journal of molecular biology High 16434054
2004 RAIDD interacts with caspase-2 via CARD in neuronal (PC12) cells; overexpression of RAIDD induces caspase-2 CARD- and caspase-9-dependent apoptosis in PC12 cells and sympathetic neurons, correlating with formation of discrete perinuclear aggregates. Both death and aggregate formation require full-length RAIDD. RAIDD overexpression, CARD deletion mutants, caspase-2 and caspase-9 inhibition assays, immunofluorescence Cell death and differentiation Medium 14765136
2006 Endogenous RAIDD is required for trophic deprivation-induced apoptosis of PC12 cells and sympathetic neurons; siRNA-mediated knockdown of RAIDD inhibited trophic-deprivation-induced (caspase-2-mediated) death but not DNA-damage-induced death, placing RAIDD specifically in the trophic factor withdrawal pathway upstream of caspase-2. siRNA knockdown, dominant-negative CARD-only caspase-2 expression, apoptosis assays with distinct stimuli Cell death and differentiation Medium 15947787
2007 The PIDD DD and RAIDD DD form an oligomeric complex of ~150 kDa in solution (as measured by gel filtration and MALS), establishing the stoichiometry and physical basis for the PIDDosome core; crystals were obtained for structural studies. Recombinant protein purification, gel filtration, multi-angle light scattering (MALS), crystallization Acta crystallographica. Section F, Structural biology and crystallization communications Medium 17329820
2010 PIDDosome assembly is time-dependent and salt concentration-dependent; point mutations RAIDD R147E and PIDD Y814A act as dominant negatives for PIDDosome formation but cannot disassemble pre-formed PIDDosome, revealing key residues at the RAIDD DD:PIDD DD interface. Recombinant protein reconstitution, mutagenesis, dominant-negative biochemical assays Biochimica et biophysica acta Medium 20406701
2012 RAIDD is required for caspase-2 activity and caspase-2-dependent neuronal death induced by NGF deprivation and amyloid-β, but PIDD is dispensable; treatment induces formation of a caspase-2/RAIDD complex independent of PIDD in neurons, defining a PIDD-independent neuronal activation complex for caspase-2. RAIDD-/- and PIDD-/- mouse neurons, co-immunoprecipitation, caspase-2 activity assays, NGF deprivation and Aβ treatments The Biochemical journal High 22515271
2012 CRADD interacts with BCL10 through its CARD domain, suppressing BCL10-CARMA1 complex formation and thereby negatively regulating TCR agonist-induced NF-κB-dependent cytokine production (IFN-γ, IL-2, TNF-α, IL-17). CRADD-deficient T cells and mice show heightened proinflammatory cytokine responses to TCR agonists. Co-immunoprecipitation (CRADD-BCL10 interaction), Cradd-/- primary T cells and mice, cytokine measurement, domain mapping Journal of immunology (Baltimore, Md. : 1950) High 22323537
2013 PIDD DD must bind to RAIDD first to open the closed conformation of full-length RAIDD, allowing subsequent recruitment of caspase-2 via CARD:CARD interaction; caspase-2 CARD alone is insoluble but is solubilized by RAIDD CARD or by full-length RAIDD in the presence of PIDD DD, defining the ordered assembly of the PIDDosome. Recombinant protein purification of all DD superfamily members, solubility assays, biochemical reconstitution BMB reports Medium 24064063
2014 CRADD interacts with BCL10 to negatively regulate the CARMA3 signalosome in endothelial cells; CRADD-deficient endothelial cells display increased IL-6 and MCP-1 expression and increased permeability with more F-actin polymerization and disrupted adherens junctions in response to LPS and thrombin. Delivery of recombinant cell-penetrating CRADD restores barrier function. cradd-/- primary murine endothelial cells, cytokine assays, permeability assays, F-actin staining, recombinant CP-CRADD protein delivery The Journal of biological chemistry Medium 24958727
2015 Genetic epistasis in the Eμ-Myc mouse lymphoma model shows that Raidd deficiency does not phenocopy Caspase-2 or Pidd1 deficiency in tumor suppression or promotion, indicating that the tumor-modulatory effects of Caspase-2 and Pidd1 can be uncoupled from their interaction with Raidd, implying alternative signaling modules. Eμ-Myc/Raidd-/- mice, tumor onset analysis, DNA-damage-driven cancer models, genetic epistasis Cell death and differentiation Medium 25857265
2016 CRADD/RAIDD mutations in the death domain (G128R, F164C, R170C, R170H) identified in patients with thin lissencephaly do not disrupt co-immunoprecipitation interactions with caspase-2 or PIDD, but abolish CRADD's ability to activate caspase-2, resulting in reduced neuronal apoptosis in vitro; homozygous Cradd knockout mice display megalencephaly and seizures, establishing CRADD/caspase-2 signaling as required for normal cortical development. Co-immunoprecipitation of TLIS variants with caspase-2 and PIDD, caspase-2 activation assays in neurons, Cradd-/- mice American journal of human genetics High 27773430
2016 RAIDD interacts with IRF7 and the kinase IKKε via co-immunoprecipitation; both the CARD and DD of RAIDD are required for IKKε- and IRF7-mediated type I interferon production (IFN-4α), placing RAIDD as a scaffold coordinating IKKε-IRF7 interaction downstream of TLR3 activation. Co-immunoprecipitation, shRNA knockdown, IFN-4α-driven dual luciferase assay, CARD and DD deletion constructs Cellular physiology and biochemistry Medium 27606466
2016 TAT-fused peptides derived from helix 3 (H3) of RAIDD and PIDD block PIDDosome formation in vitro and inhibit rotenone-induced caspase-2-dependent apoptosis in neuronal cells, confirming H3 as a critical interface for RAIDD:PIDD DD interaction. In vitro PIDDosome reconstitution assay, TAT-peptide inhibition, caspase-2 activity assay, neuronal cell death assay Scientific reports Medium 27502430
2018 TLIS-associated RAIDD DD mutations (G128R, F164C, R170C, R170H) were shown by mutagenesis and biochemical assays to disrupt DD:DD interaction with PIDD, providing the molecular mechanism by which these mutations reduce caspase-2-mediated neuronal apoptosis. Mutagenesis, biochemical binding assays (pulldown/co-IP of DD mutants with PIDD DD) PloS one Medium 30281648
2014 HDAC1 binds directly to the CRADD promoter and represses its expression in gastric cancer; HDAC1 siRNA upregulates CRADD, and CRADD induction by the HDAC inhibitor TSA activates caspase-2-dependent apoptosis, establishing HDAC1 as a negative transcriptional regulator of the CRADD-caspase-2 axis. ChIP (HDAC1 binding to CRADD promoter), siRNA knockdown, TSA treatment, caspase-2 activation assay American journal of translational research Medium 25360218

Source papers

Stage 0 corpus · 31 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1997 RAIDD is a new 'death' adaptor molecule. Nature 455 8985253
1998 Solution structure of the RAIDD CARD and model for CARD/CARD interaction in caspase-2 and caspase-9 recruitment. Cell 271 9695946
1997 CRADD, a novel human apoptotic adaptor molecule for caspase-2, and FasL/tumor necrosis factor receptor-interacting protein RIP. Cancer research 225 9044836
2005 Apoptosis caused by p53-induced protein with death domain (PIDD) depends on the death adapter protein RAIDD. Proceedings of the National Academy of Sciences of the United States of America 89 16183742
2000 Fas ligand-induced c-Jun kinase activation in lymphoid cells requires extensive receptor aggregation but is independent of DAXX, and Fas-mediated cell death does not involve DAXX, RIP, or RAIDD. Journal of immunology (Baltimore, Md. : 1950) 56 10903735
2000 Subcellular localization and CARD-dependent oligomerization of the death adaptor RAIDD. Cell death and differentiation 52 10713730
2016 Mutations in CRADD Result in Reduced Caspase-2-Mediated Neuronal Apoptosis and Cause Megalencephaly with a Rare Lissencephaly Variant. American journal of human genetics 50 27773430
2011 LBH589, a deacetylase inhibitor, induces apoptosis in adult T-cell leukemia/lymphoma cells via activation of a novel RAIDD-caspase-2 pathway. Leukemia 43 21242994
2012 Neuronal caspase 2 activity and function requires RAIDD, but not PIDD. The Biochemical journal 35 22515271
2006 Crystal structure of RAIDD death domain implicates potential mechanism of PIDDosome assembly. Journal of molecular biology 26 16434054
1998 A 500-kb YAC and BAC contig encompassing the high-growth deletion in mouse chromosome 10 and identification of the murine Raidd/Cradd gene in the candidate region. Genomics 22 9806843
2017 Homozygous null variant in CRADD, encoding an adaptor protein that mediates apoptosis, is associated with lissencephaly. American journal of medical genetics. Part A 20 28686357
2015 The tumor-modulatory effects of Caspase-2 and Pidd1 do not require the scaffold protein Raidd. Cell death and differentiation 20 25857265
2004 RAIDD aggregation facilitates apoptotic death of PC12 cells and sympathetic neurons. Cell death and differentiation 18 14765136
2001 Expression of apoptosis related proteins: RAIDD, ZIP kinase, Bim/BOD, p21, Bax, Bcl-2 and NF-kappaB in brains of patients with Down syndrome. Journal of neural transmission. Supplementum 16 11771742
2009 RAIDD expression is impaired in multidrug resistant osteosarcoma cell lines. Cancer chemotherapy and pharmacology 14 19125251
2007 Crystallization and preliminary X-ray crystallographic studies of the oligomeric death-domain complex between PIDD and RAIDD. Acta crystallographica. Section F, Structural biology and crystallization communications 14 17329820
2019 Phenotypic spectrum associated with a CRADD founder variant underlying frontotemporal predominant pachygyria in the Finnish population. European journal of human genetics : EJHG 13 30914828
2013 PIDD mediates and stabilizes the interaction between RAIDD and caspase-2 for the PIDDosome assembly. BMB reports 13 24064063
2010 Identification and analysis of dominant negative mutants of RAIDD and PIDD. Biochimica et biophysica acta 13 20406701
2012 Cutting edge: the "death" adaptor CRADD/RAIDD targets BCL10 and suppresses agonist-induced cytokine expression in T lymphocytes. Journal of immunology (Baltimore, Md. : 1950) 12 22323537
2006 RAIDD is required for apoptosis of PC12 cells and sympathetic neurons induced by trophic factor withdrawal. Cell death and differentiation 12 15947787
2014 Regulation of CRADD-caspase 2 cascade by histone deacetylase 1 in gastric cancer. American journal of translational research 9 25360218
2021 CRADD and USP44 mutations in intellectual disability, mild lissencephaly, brain atrophy, developmental delay, strabismus, behavioural problems and skeletal anomalies. European journal of medical genetics 8 33647455
2016 Rescuing neuronal cell death by RAIDD- and PIDD- derived peptides and its implications for therapeutic intervention in neurodegenerative diseases. Scientific reports 8 27502430
2014 The adaptor CRADD/RAIDD controls activation of endothelial cells by proinflammatory stimuli. The Journal of biological chemistry 8 24958727
2009 Purification, crystallization and preliminary x-ray crystallographic studies of RAIDD Death-Domain (DD). International journal of molecular sciences 8 19582216
2003 Overexpression of Raidd cDNA inhibits differentiation of mouse preadipocytes. Cell proliferation 7 12558660
2018 RAIDD mutations underlie the pathogenesis of thin lissencephaly (TLIS). PloS one 5 30281648
2016 RAIDD Mediates TLR3 and IRF7 Driven Type I Interferon Production. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 5 27606466
2024 CRADD and cIAP1 antagonistically regulate caspase-9-mediated apoptosis in teleost. International journal of biological macromolecules 3 39233177