Affinage

DIABLO

Diablo IAP-binding mitochondrial protein · UniProt Q9NR28

Length
239 aa
Mass
27.1 kDa
Annotated
2026-06-09
100 papers in source corpus 37 papers cited in narrative 36 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 9/9 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SMAC/DIABLO is a mitochondrial intermembrane-space protein that acts as a central antagonist of inhibitor-of-apoptosis proteins (IAPs), de-repressing caspase activation during programmed cell death (PMID:10972280, PMID:21597464). It is synthesized as a precursor whose N-terminal targeting sequence is removed by the inner-membrane peptidase (IMP) complex and further by the rhomboid protease PARL to expose a mature Ala-Val-Pro-Ile IAP-binding motif essential for activity (PMID:15814844, PMID:28288130). The functional protein homodimerizes through a hydrophobic interface, and this N-terminal tetrapeptide inserts into a surface groove on the XIAP BIR3 domain in a mode that is mutually exclusive with binding of the caspase-9 linker peptide, so SMAC competitively displaces caspase-9 from BIR3 while also neutralizing IAP inhibition of effector caspases through BIR1/BIR2 contacts (PMID:10972280, PMID:11140638, PMID:11140637, PMID:11242052, PMID:10950947). Beyond steric antagonism, SMAC represses and degrades IAPs: it inhibits the RING-dependent ubiquitin-ligase activity of XIAP, cIAP1 and cIAP2 and drives proteasomal degradation of cIAP1/2, while being reciprocally targeted for ubiquitination and degradation by cIAP1/2, Apollon/BIRC6 and Livin (PMID:15300255, PMID:12525502, PMID:14960576, PMID:15078891, PMID:16729033). Cryo-EM of the BIRC6 dimer shows SMAC binding multivalently with subnanomolar affinity to obstruct client sites and block BIRC6-mediated ubiquitination of both apoptotic (caspase-9) and autophagy (LC3B) substrates (PMID:36758105, PMID:36758106). SMAC additionally binds Survivin and is sequestered by it at the same N-terminal-Ala recognition site, linking SMAC to a wider network of BIR-domain partners (PMID:12660240, PMID:22244766, PMID:17546047). Mitochondrial release of SMAC is gated by Bcl-2/Bcl-xL and accompanies cytochrome c efflux during apoptotic membrane permeabilization, and SMAC is required for full caspase-3 processing in death-receptor (TRAIL), NSAID-, and PUMA-driven death (PMID:11782443, PMID:11726499, PMID:11741882, PMID:15557007, PMID:17237824). Single knockout mice are viable, but combined loss of Diablo and Casp3 causes perinatal lethality, establishing a physiological role in regulating cell death (PMID:11971981, PMID:21597464). A heterozygous missense mutation (p.Ser71Leu) causes dominant non-syndromic hearing loss DFNA64 through a gain-of-function mitochondrial defect (PMID:21722859).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 2000 High

    Established the structural basis of SMAC/DIABLO function: how it dimerizes and how its N-terminus engages IAPs to promote caspase activation.

    Evidence X-ray crystallography of SMAC alone and bound to XIAP BIR3, NMR of the BIR3-peptide complex, with dimer-interface and N-terminal mutagenesis

    PMID:10950947 PMID:10972280 PMID:11140637 PMID:11140638

    Open questions at the time
    • Did not resolve how the N-terminal motif is exposed in vivo
    • Distinct contributions of BIR1/BIR2 versus BIR3 engagement only partially defined
  2. 2001 High

    Defined the competitive mechanism by showing SMAC and the cleaved caspase-9 linker peptide share an IAP-binding motif and bind BIR3 mutually exclusively, explaining how SMAC potentiates caspase-9.

    Evidence Co-IP, caspase-9 cleavage-site mutagenesis, and competitive BIR3 binding assays

    PMID:11242052

    Open questions at the time
    • Did not address effector-caspase de-repression in cells
    • In vitro competition not validated by structural snapshot of the ternary state
  3. 2001 Medium

    Resolved the cell-biological gating of SMAC release, showing it exits mitochondria during apoptosis under Bcl-2/Bcl-xL control with kinetics coupled to membrane depolarization.

    Evidence Subcellular fractionation and live-cell imaging with Bcl-2/Bcl-xL overexpression and caspase inhibitors

    PMID:11726499 PMID:11741882

    Open questions at the time
    • Caspase-dependence of release disputed across stimuli (see #18, #34)
    • Channel/permeabilization mechanism for SMAC efflux not defined
  4. 2002 High

    Tested the in vivo requirement for SMAC, revealing functional redundancy under basal conditions despite a clear in vitro caspase-3 activation defect.

    Evidence Smac-null knockout mice with phenotypic and cell-free caspase analyses

    PMID:11971981

    Open questions at the time
    • Did not identify the redundant factor
    • Left open whether combined genetic loss would reveal a phenotype (resolved 2011, #20)
  5. 2002 High

    Connected SMAC to death-receptor signaling, showing its Bax-dependent release is required to neutralize XIAP for complete caspase-3 processing in TRAIL apoptosis.

    Evidence Bax-null cells with cytosolic SMAC reconstitution and caspase-9 epistasis

    PMID:11782443

    Open questions at the time
    • Did not quantify XIAP threshold setting the Bax requirement
    • Generalizability beyond the cancer lines tested unaddressed
  6. 2003 Medium

    Showed SMAC is reciprocally regulated and itself a ubiquitination substrate, while it both antagonizes and degrades IAPs, expanding its role from steric blocker to regulator of IAP ligase activity.

    Evidence In vitro and in vivo ubiquitination assays with cIAP1/2 and Livin, RING/BIR mutants, and a cytosolic ubiquitin-fusion SMAC expression system

    PMID:12511567 PMID:12525502 PMID:14960576 PMID:15078891 PMID:16729033

    Open questions at the time
    • E2 enzyme assignments incompletely mapped
    • Selectivity for cIAP1/2 over XIAP degradation mechanistically unexplained
  7. 2003 Medium

    Identified Survivin as a BIR-domain partner that sequesters SMAC, and defined the shared N-terminal-Ala recognition mode, linking SMAC antagonism to Survivin-mediated apoptosis suppression.

    Evidence Co-IP, BIR mutagenesis, NMR and crystallographic mapping of the Survivin-SMAC peptide interface with calorimetry

    PMID:12660240 PMID:15628841 PMID:17546047 PMID:22244766

    Open questions at the time
    • Physiological stoichiometry of SMAC-Survivin sequestration unclear
    • Competition with H3T3ph for the same site not resolved in cells
  8. 2004 High

    Established Apollon/BIRC6 as an IAP that binds and degrades SMAC via its IAP-binding motif, and distinguished NAIP as an IAP not antagonized by SMAC.

    Evidence In vitro ubiquitination, Apollon knockout mice and rescue with motif mutants; recombinant NAIP binding assays

    PMID:15280366 PMID:15300255

    Open questions at the time
    • BIRC6 architecture and binding mode not yet structurally resolved (later #31)
    • Tissue-specific contribution of BIRC6-SMAC degradation undefined
  9. 2005 Medium

    Defined the proteolytic maturation pathway, identifying IMP-mediated cleavage that generates the exposed IAP-binding motif on the inner membrane.

    Evidence Yeast IMP complementation with mammalian subunits and cellular processing assays

    PMID:15814844

    Open questions at the time
    • Did not establish whether IMP cleavage alone produces the final mature N-terminus
    • Relationship to later-identified PARL processing unaddressed
  10. 2006 Medium

    Placed SMAC downstream of E2F1, showing direct transcriptional upregulation that contributes to E2F1-induced mitochondrial apoptosis.

    Evidence Promoter reporter assays, ChIP, inducible E2F1, and siRNA rescue

    PMID:16617145

    Open questions at the time
    • Other transcriptional inputs not surveyed
    • In vivo relevance of E2F1-SMAC axis untested
  11. 2011 High

    Demonstrated a physiological cell-death role through genetic epistasis, with Diablo;Casp3 double loss causing perinatal lethality, and a disease link via the DFNA64 gain-of-function mutation.

    Evidence Double-knockout mice with siRNA epistasis on IAPs and executioner caspases; linkage analysis plus functional study of the S71L mutant

    PMID:21597464 PMID:21722859

    Open questions at the time
    • Mechanism connecting SMAC dysfunction to cochlear pathology incomplete
    • Identity of the IAP-caspase modules dominating each tissue unresolved
  12. 2017 High

    Completed the maturation model by identifying PARL as the inner-membrane protease that generates the IAP-binding motif required for apoptotic competence.

    Evidence PARL proteomics, knockout cells, SMAC-XIAP Co-IP, N-terminal sequencing, and multi-modal rescue

    PMID:28288130

    Open questions at the time
    • Coordination/order of IMP versus PARL cleavage not fully reconciled
    • Regulation of PARL processing under apoptotic stimuli unaddressed
  13. 2023 High

    Provided the structural mechanism for BIRC6 antagonism, showing SMAC multivalently blocks the BIRC6 client cavity to inhibit ubiquitination of both apoptotic and autophagy substrates.

    Evidence Cryo-EM of the BIRC6 dimer with SMAC, ubiquitination assays identifying UBA6, and caspase inhibition assays

    PMID:36758105 PMID:36758106

    Open questions at the time
    • Cellular regulation of SMAC-BIRC6 stoichiometry not addressed
    • Whether SMAC similarly blocks other BIR-megaligases unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • Whether SMAC/DIABLO's reported non-apoptotic role in phospholipid synthesis reflects a direct biochemical activity rather than an indirect transcriptional consequence remains unresolved.
  • No direct interaction or enzymatic activity linking SMAC to lipid metabolism identified
  • Lipid phenotype rests on a single siRNA/transcriptome study (#33)

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 5 GO:0140096 catalytic activity, acting on a protein 2
Localization
GO:0005739 mitochondrion 4 GO:0005829 cytosol 3
Pathway
R-HSA-392499 Metabolism of proteins 4 R-HSA-5357801 Programmed Cell Death 3
Partners
BIRC2BIRC3BIRC5BIRC6BIRC7CASP9XIAP

Evidence

Reading pass · 36 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 Crystal structure of Smac/DIABLO at 2.2 Å resolution reveals that it homodimerizes through an extensive hydrophobic interface; missense mutations inactivating the dimeric interface significantly compromise Smac/DIABLO function. The N-terminal amino acids are indispensable for function, and a seven-residue N-terminal peptide promotes procaspase-3 activation in vitro. Smac/DIABLO promotes both proteolytic activation of procaspase-3 and enzymatic activity of mature caspase-3 through physical interaction with IAPs. X-ray crystallography (2.2 Å), in vitro procaspase-3 activation assay, mutagenesis of dimer interface Nature High 10972280
2000 Crystal structure of Smac/DIABLO complexed with the BIR3 domain of XIAP at high resolution shows that the N-terminal four residues (Ala-Val-Pro-Ile) of mature Smac bind a surface groove on BIR3, with the first residue Ala making five hydrogen bonds to BIR3 residues and occupying a hydrophobic pocket. Mutation of the very first amino acid abolishes IAP interaction and Smac/DIABLO function. X-ray crystallography (high-resolution co-crystal structure), mutagenesis, binding assays Nature High 11140638
2000 NMR solution structure of the XIAP BIR3 domain complexed with a nine-residue Smac N-terminal peptide reveals that the peptide binds across the third beta-strand of BIR3 in an extended conformation; only the first four residues contact the protein, stabilized by four intermolecular hydrogen bonds, an electrostatic interaction at the peptide N-terminus, and hydrophobic contacts. BIR3 and Smac peptide mutants confirmed these contacts. NMR solution structure, binding assays with BIR3 and peptide mutants Nature High 11140637
2001 XIAP binds the active caspase-9–Apaf-1 holoenzyme through the N-terminus of the linker peptide on the caspase-9 small subunit exposed after cleavage at Asp315. The N-terminal four residues of this linker share homology with the Smac N-terminal tetra-peptide, defining a conserved IAP-binding motif. Smac/DIABLO binding to BIR3 is mutually exclusive with caspase-9 linker peptide binding, demonstrating that Smac potentiates caspase-9 activity by competing for the BIR3 binding site. Co-immunoprecipitation, point mutagenesis of caspase-9 cleavage site, competitive binding assays with BIR3 Nature High 11242052
2000 Smac/DIABLO N-terminal sequences are required for interaction with IAP BIR3 (blocking caspase-9 inhibition) but the N-terminus is less critical for interaction with BIR1/BIR2 and promotion of effector caspase activity. Smac functions at both the apoptosome level (via BIR3) and effector caspase level (via BIR1/BIR2), neutralizing IAP inhibition. In vitro caspase activation assays, deletion/truncation mutants of Smac, co-immunoprecipitation with XIAP domains The Journal of biological chemistry High 10950947
2002 TRAIL-induced apoptosis in human cancer cells requires Bax-dependent mitochondrial release of Smac/DIABLO to neutralize XIAP and permit complete caspase-3 processing. Bax null cells show incomplete caspase-3 processing due to XIAP inhibition; cytosolic expression of active Smac/DIABLO in Bax-deficient cells reconstitutes TRAIL sensitivity. Caspase-9 inhibition does not affect TRAIL-induced caspase-3 activation, establishing Smac/DIABLO release (not cytochrome c) as the key mitochondrial contribution to death receptor apoptosis. Bax-null cancer cell lines, cytosolic Smac/DIABLO reconstitution, caspase-9 inhibition, Western blot for caspase processing Genes & development High 11782443
2001 Mitochondrial release of Smac/DIABLO into the cytosol during apoptosis is blocked by Bcl-2 overexpression, showing Bcl-2 regulates Smac export. Unlike cytochrome c release (largely caspase-independent), Smac/DIABLO efflux is blocked by a broad-spectrum caspase inhibitor, demonstrating that Smac release is a caspase-dependent event downstream of cytochrome c release. Subcellular fractionation, Bcl-2-overexpressing cell lines, broad-spectrum caspase inhibitor (z-VAD-fmk), Western blot The EMBO journal High 11726499
2004 Apollon (BIRC6) binds to, ubiquitinates, and promotes proteasomal degradation of SMAC/DIABLO (as well as caspase-9), both of which contain IAP-binding motifs. In Apollon-deficient cells, SMAC induces apoptosis; this requires the IAP-binding motif of SMAC, establishing that Apollon prevents SMAC-induced apoptosis through ubiquitin-mediated degradation. Co-immunoprecipitation, in vitro ubiquitination assay, Apollon knockout mice, cell death assays in Apollon-deficient cells Nature cell biology High 15300255
2003 cIAP1 and cIAP2 act as E3 ubiquitin ligases for Smac/DIABLO, stimulating its ubiquitination both in vivo and in vitro via their RING domains, leading to Smac degradation. The substrate-dependent E3 activity requires physical interaction between cIAPs and Smac, and cIAP1/2 associate with overlapping but distinct E2 ubiquitin-conjugating enzymes. In vitro ubiquitination assay, in vivo ubiquitination in cells, RING domain mutants, E2 enzyme identification The Journal of biological chemistry High 12525502
2004 Smac/DIABLO selectively promotes rapid degradation of cIAP1 and cIAP2 but not XIAP or Livin in HeLa cells via the ubiquitin/proteasome pathway. Smac binding via its N-terminal IAP-binding motif is prerequisite for this effect; Smac N-terminal peptide alone is sufficient to enhance cIAP1 ubiquitination, and mutant cIAP1 lacking all BIR domains is not ubiquitinated by Smac. Cell-based degradation assays, N-terminal peptide competition, BIR domain deletion mutants, auto-ubiquitination assays The Journal of biological chemistry Medium 14960576
2004 Smac/DIABLO binding to IAPs (XIAP, cIAP-1, cIAP2) potently represses their ubiquitin ligase activities. Mutation of the XIAP RING domain reduces its anti-apoptotic efficacy, suggesting that XIAP ubiquitin ligase activity contributes to apoptosis inhibition and Smac antagonizes this in addition to blocking caspase-IAP interactions. In vitro ubiquitination assay, RING domain mutagenesis, cell-based apoptosis assays The Journal of biological chemistry Medium 15078891
2005 Mature DIABLO/Smac is produced by the inner membrane peptidase (IMP) complex on the mitochondrial inner membrane. The precursor enters mitochondria through a stop-transfer pathway and is cleaved by IMP to generate the active form with the exposed N-terminal IAP-binding motif. Complementation of yeast IMP mutants with mammalian IMP subunits, cellular processing assays, identification of IMP catalytic subunits by sequence conservation Molecular biology of the cell Medium 15814844
2017 The rhomboid intramembrane protease PARL in the mitochondrial inner membrane cleaves Smac/DIABLO to generate the N-terminal IAP-binding motif required for apoptotic activity. Loss of PARL impairs Smac proteolytic maturation; PARL-deficient cells show reduced Smac–XIAP binding and impaired apoptosis, which is rescued by Smac peptidomimetics, XIAP downregulation, or cytosolic expression of pre-cleaved Smac. PARL-based proteomics, PARL knockout cells, co-immunoprecipitation of Smac-XIAP, rescue experiments, N-terminal sequencing of cleaved Smac Nature cell biology High 28288130
2006 Livin (an IAP family member) acts as an E3 ubiquitin ligase for Smac/DIABLO; both the BIR and RING domains of Livin are required for Smac degradation in vitro and in vivo. Mutation of the Livin BIR domain abolishes Smac/DIABLO binding and prevents its degradation. In vitro and in vivo ubiquitination assays, BIR and RING domain mutants, co-immunoprecipitation Cell death and differentiation Medium 16729033
2003 Survivin physically interacts with Smac/DIABLO both in vitro and in vivo (co-immunoprecipitation). A point mutation (D71R) in the Survivin BIR motif and a C-terminal deletion mutant (Surv-BIR) abolish Smac/DIABLO binding and abrogate apoptosis inhibition. The N-terminus of mature Smac is required for Survivin-Smac complex formation. Co-presence of Smac/DIABLO and XIAP is required for Survivin to inhibit caspase cleavage in a cell-free system. Co-immunoprecipitation, in vitro binding, BIR domain point mutation (D71R), cell-free caspase inhibition assay The Journal of biological chemistry Medium 12660240
2005 NMR studies show that Smac/DIABLO N-terminal peptides bind across the third beta-strand of the Survivin BIR domain (near alpha4 and beta3), analogous to Smac binding to XIAP BIR3, as demonstrated by specific chemical shift perturbations in Survivin residues upon Smac peptide addition. NMR chemical shift perturbation mapping with Smac/DIABLO N-terminal peptides and Survivin Biochemistry Medium 15628841
2012 Crystal structures of Survivin complexed with Smac/DIABLO N-terminal peptide and with phospho-Thr3 histone H3 peptide establish that Survivin recognizes N-terminal Ala in both ligands at the same binding site. Calorimetric data show Survivin binds the H3T3ph peptide more tightly than the Smac/DIABLO N-terminal peptide; structure-guided mutations increasing hydrophobicity of the phosphate-binding pocket reversed this preference. X-ray crystallography, isothermal titration calorimetry, structure-guided mutagenesis Structure High 22244766
2001 tBid triggers rapid and essentially complete co-release of Smac/DIABLO and cytochrome c from mitochondria with similar kinetics (onset and completion synchronized), occurring after a ~10 s delay and completing within 50–70 s, coinciding with mitochondrial membrane potential depolarization. Bcl-xL prevents tBid-induced release of both proteins. GFP/YFP fusion proteins, real-time fluorescence imaging, rapid filtration Western blot, permeabilized HepG2 cells The Journal of biological chemistry Medium 11741882
2003 Real-time confocal imaging of MCF-7 cells expressing Smac/DIABLO-YFP shows that Smac/DIABLO and cytochrome c release onset is simultaneous and coincides with mitochondrial membrane potential depolarization. Smac/DIABLO release kinetics are not affected by caspase inhibition (z-VAD-fmk) or caspase-3 deficiency. DEVDase (caspase-3/7) activation occurs within 10 min of Smac/DIABLO release even without caspase-3. Stable Smac/DIABLO-YFP expression, real-time confocal microscopy, caspase inhibitor (z-VAD-fmk), caspase-3-deficient MCF-7 cells, DEVDase activity assay The Journal of cell biology Medium 12975347
2002 Smac/DIABLO-deficient (Smac−/−) mice generated by homologous recombination are viable, develop normally, and show no histological abnormalities. Cultured Smac−/− cells respond normally to apoptotic stimuli and show no difference in Fas-mediated apoptosis in vivo, though in vitro procaspase-3 cleavage is inhibited in cell lysates, indicating functional redundancy in vivo. Homologous recombination knockout mice, in vitro cell death assays, in vivo Fas-mediated apoptosis, cell-free caspase-3 activation assay Molecular and cellular biology High 11971981
2011 Combinatorial deletion of Diablo and Casp3 (but neither alone) causes perinatal lethality in mice, demonstrating a physiological role for Smac/DIABLO in regulating programmed cell death. In MEFs, loss of Smac/DIABLO alters both caspase-dependent and caspase-independent intrinsic PCD. siRNA epistasis experiments show Smac/DIABLO modulates inhibitory interactions between specific IAP family members and executioner caspases-3 and -7. Double-knockout mouse generation, MEF cell death assays, siRNA epistasis (XIAP, cIAP-1, cIAP-2, caspase-6, -7) Cell death and differentiation High 21597464
2003 Smac/DIABLO-induced apoptosis in ovarian carcinoma cells proceeds primarily through a caspase-9-mediated pathway; it is inhibited by XIAP overexpression and the caspase-9 inhibitor zLEHD-fmk. Smac-induced apoptosis occurs independently of cytochrome c release from mitochondria and is not inhibited by Bcl-2 overexpression when Smac is expressed ectopically. Recombinant adenovirus-mediated Smac expression, caspase inhibitors, XIAP overexpression, Bcl-2 overexpression, Western blot for caspase cleavage Experimental cell research Medium 12749848
2011 A heterozygous SMAC/DIABLO missense mutation (c.377C>T; p.Ser71Leu in the mature protein) causes dominant progressive non-syndromic hearing loss (DFNA64). The mutant SMAC/DIABLO(S71L) retains proapoptotic function but triggers significant degradation of both wild-type and mutant SMAC/DIABLO and renders host mitochondria susceptible to calcium-induced loss of membrane potential, indicating a gain-of-function mitochondrial dysfunction. Linkage analysis, mutation identification, in vitro functional study with S71L mutant expression, mitochondrial membrane potential assay, Western blot for Smac protein levels American journal of human genetics Medium 21722859
2006 E2F1 directly binds to and activates the SMAC/DIABLO promoter through two E2F1-binding sites (BS2 at −542/−535 bp and BS3 at −200/−193 bp), upregulating Smac/DIABLO mRNA and protein to enhance mitochondria-mediated apoptosis. This activation is E2F1-specific (E2F2 and E2F3 cannot activate these sites). siRNA knockdown of Smac/DIABLO significantly diminishes E2F1-induced apoptosis. Promoter luciferase reporter assays, ChIP, inducible ER-E2F1 cell line (4-OHT induction), RT-PCR, Western blot, siRNA knockdown Nucleic acids research Medium 16617145
2007 Mitochondrial survivin associates with Smac/DIABLO and delays its release during etoposide-induced apoptosis; cytosolic survivin also stabilizes released Smac/DIABLO levels. This selective retention of Smac/DIABLO (but not other intermembrane space proteins) explains the survivin anti-apoptotic effect in cancer cells. Co-immunoprecipitation of mitochondrial survivin with Smac/DIABLO, subcellular fractionation, etoposide treatment, Western blot for Smac release kinetics Oncogene Medium 17546047
2004 NAIP (neuronal apoptosis-inhibitory protein) fails to interact with the IAP-binding motif of Smac/DIABLO, and Smac protein does not interact with NAIP BIR domains, demonstrating that NAIP's mechanism of caspase inhibition is distinct from other IAPs and is not countered by Smac. This is a negative mechanistic finding distinguishing NAIP from XIAP. Recombinant protein binding assays with full-length NAIP and Smac; IAP-binding motif peptide competition assay The Journal of biological chemistry Medium 15280366
2003 SMAC/Diablo is essential for NSAID-induced apoptosis in colon cancer cells. Homologous recombination disruption and siRNA knockdown of SMAC/Diablo abrogates NSAID-induced apoptosis; reconstitution restores it. Loss of SMAC decreases caspase activation, cytochrome c release, and mitochondrial membrane potential collapse in this context. Homologous recombination gene disruption, siRNA knockdown, reconstitution, caspase activity assays, cytochrome c release (Western blot), mitochondrial membrane potential assay Proceedings of the National Academy of Sciences of the United States of America High 15557007
2007 SMAC/Diablo mediates the proapoptotic function of PUMA: in SMAC-deficient cells, PUMA-induced apoptosis is abrogated with decreases in caspase activation, cytochrome c release, and mitochondrial membrane potential collapse. Reconstitution of SMAC restores these events, and SMAC participates in a feedback amplification loop promoting cytochrome c release during DNA damage-induced apoptosis. SMAC-deficient cell lines, SMAC reconstitution, caspase activity assays, cytochrome c release (Western blot), mitochondrial membrane potential Oncogene Medium 17237824
2003 A ubiquitin fusion system generates mature, biologically active Smac directly in the cytosol with correct N-terminal Ala-Val-Pro-Ile sequence (without mitochondrial processing). This cytosolic Smac interacts with XIAP and sensitizes cells to apoptotic triggers (etoposide) but is not sufficient alone to trigger apoptosis in healthy cells. Ubiquitin fusion expression construct, N-terminal sequencing, co-immunoprecipitation with XIAP, cell death assays with etoposide The Journal of biological chemistry Medium 12511567
2003 Synthetic Smac/DIABLO N-terminal peptides (first 4–8 amino acids) fused to the antennapaedia penetratin carrier enter cells, bind XIAP and cIAP1 in situ, displace caspase-3 from cytoplasmic aggregates, and enhance drug-induced caspase activity and apoptosis when combined with chemotherapeutic agents. Cell-permeable peptide delivery, co-immunoprecipitation of peptide with XIAP/cIAP1, caspase activity assays, long-term antiproliferative assays The Journal of biological chemistry Medium 12218061
2003 Cephalostatin 1 selectively triggers mitochondrial release of Smac/DIABLO without releasing cytochrome c, AIF, or activating caspase-8-dependent death receptors, defining a novel apoptosis pathway that uses Smac/DIABLO as the key mitochondrial signaling molecule. Bcl-xL overexpression delays both Smac/DIABLO release and apoptosis onset. Western blot for selective protein release, Bcl-xL overexpression, CD95/caspase-8-deficient cells, caspase inhibitor, electron microscopy Cancer research Medium 14695204
2023 Cryo-EM structures of BIRC6 in complex with SMAC reveal that BIRC6 forms a megadalton antiparallel dimer with a spacious cavity containing receptor sites for client proteins (caspase-9, HTRA2, LC3B). SMAC binds multivalently to BIRC6 with subnanomolar affinity, obstructing client binding sites and thereby impeding ubiquitination of both apoptotic (caspase-9) and autophagy (LC3B) substrates. BIRC6 directly restricts executioner caspase-3 and -7 and ubiquitinates caspases-3, -7, and -9 exclusively with noncanonical E1 enzyme UBA6. Cryo-EM structure determination, ubiquitination assays identifying UBA6 as E1, caspase activity assays, competitive displacement assays with SMAC Science High 36758105 36758106
2004 Direct interaction between Smac/DIABLO and NADE (p75NTR-associated cell death executor) was identified by binding screen. The N-terminal region of Smac and C-terminal region of NADE mediate the interaction. Co-expression of NADE and Smac promotes TRAIL-induced apoptosis in MCF-7 cells. Co-presence of Smac and NADE inhibits XIAP-mediated Smac ubiquitination. Protein interaction screen, co-immunoprecipitation, domain mapping, cell-based apoptosis and ubiquitination assays Biochemical and biophysical research communications Low 15178455
2020 SMAC/Diablo has a non-apoptotic function in phospholipid synthesis: siRNA silencing of SMAC/Diablo in cancer cells and xenografts reduced cell and tumor growth, altered expression of genes involved in lipid metabolism, and decreased phospholipid (including phosphatidylcholine) levels. This suggests SMAC/Diablo regulates lipid synthesis essential for cancer cell proliferation. siRNA knockdown in cancer cell lines and subcutaneous xenografts, next-generation sequencing of transcriptome, phospholipid quantification, electron microscopy Molecular therapy Low 29396267
2005 During UV-induced apoptosis in HeLa cells, YFP-Smac and GFP-cytochrome c are released from mitochondria in the same time window coinciding with mitochondrial membrane potential depolarization, and endogenous Smac and cytochrome c are always released together within individual cells. Pre-treatment with z-VAD-fmk does not affect Smac release, indicating caspase-independent release in this context (contrasting with the Adrain et al. finding in other apoptotic models). Live-cell confocal microscopy with dual YFP-Smac / GFP-cytochrome c fusion proteins, immunostaining of endogenous proteins, z-VAD-fmk treatment Apoptosis Medium 15843890
2003 A novel Smac/DIABLO splice variant, Smac3, is generated by alternative splicing of exon 4. Smac3 localizes to mitochondria via its N-terminal targeting sequence, is released into cytosol during apoptosis, binds BIR2 and BIR3 of XIAP via its IAP-binding motif, disrupts caspase-9–XIAP interaction, promotes caspase-3 activation, and uniquely accelerates XIAP auto-ubiquitination and destruction (unlike canonical Smac/DIABLO). Cloning/sequencing, mitochondrial targeting assay, co-immunoprecipitation with XIAP domains, caspase-3 activation assay, XIAP ubiquitination assay The Journal of biological chemistry Medium 14523016

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 A conserved XIAP-interaction motif in caspase-9 and Smac/DIABLO regulates caspase activity and apoptosis. Nature 817 11242052
2000 Structural basis of IAP recognition by Smac/DIABLO. Nature 682 11140638
2000 Structural and biochemical basis of apoptotic activation by Smac/DIABLO. Nature 667 10972280
2000 Structural basis for binding of Smac/DIABLO to the XIAP BIR3 domain. Nature 526 11140637
2002 TRAIL-induced apoptosis requires Bax-dependent mitochondrial release of Smac/DIABLO. Genes & development 389 11782443
2001 Apoptosis-associated release of Smac/DIABLO from mitochondria requires active caspases and is blocked by Bcl-2. The EMBO journal 351 11726499
2003 Direct interaction between survivin and Smac/DIABLO is essential for the anti-apoptotic activity of survivin during taxol-induced apoptosis. The Journal of biological chemistry 315 12660240
2000 Molecular determinants of the caspase-promoting activity of Smac/DIABLO and its role in the death receptor pathway. The Journal of biological chemistry 279 10950947
2002 Synthetic Smac/DIABLO peptides enhance the effects of chemotherapeutic agents by binding XIAP and cIAP1 in situ. The Journal of biological chemistry 229 12218061
2015 Reactive oxygen species regulate Smac mimetic/TNFα-induced necroptotic signaling and cell death. Oncogene 206 25867066
2004 Apollon ubiquitinates SMAC and caspase-9, and has an essential cytoprotection function. Nature cell biology 200 15300255
2003 Cellular inhibitor of apoptosis 1 and 2 are ubiquitin ligases for the apoptosis inducer Smac/DIABLO. The Journal of biological chemistry 194 12525502
2014 Small-molecule SMAC mimetics as new cancer therapeutics. Pharmacology & therapeutics 170 24841289
2004 Smac/DIABLO selectively reduces the levels of c-IAP1 and c-IAP2 but not that of XIAP and livin in HeLa cells. The Journal of biological chemistry 167 14960576
2004 Caspases, IAPs and Smac/DIABLO: mechanisms from structural biology. Trends in biochemical sciences 167 15337122
2015 Promises and Challenges of Smac Mimetics as Cancer Therapeutics. Clinical cancer research : an official journal of the American Association for Cancer Research 160 26567362
2001 Rapid kinetics of tBid-induced cytochrome c and Smac/DIABLO release and mitochondrial depolarization. The Journal of biological chemistry 160 11741882
2002 Generation and characterization of Smac/DIABLO-deficient mice. Molecular and cellular biology 145 11971981
2002 Cell death regulation by the mammalian IAP antagonist Diablo/Smac. Apoptosis : an international journal on programmed cell death 134 11865200
2010 Apoptosis is regulated by the VDAC1 N-terminal region and by VDAC oligomerization: release of cytochrome c, AIF and Smac/Diablo. Biochimica et biophysica acta 128 20214874
2003 Real-time single cell analysis of Smac/DIABLO release during apoptosis. The Journal of cell biology 127 12975347
2017 PARL mediates Smac proteolytic maturation in mitochondria to promote apoptosis. Nature cell biology 125 28288130
2020 Future Therapeutic Directions for Smac-Mimetics. Cells 118 32053868
2001 Sphingosine 1-phosphate antagonizes apoptosis of human leukemia cells by inhibiting release of cytochrome c and Smac/DIABLO from mitochondria. Blood 114 11675357
2006 Targeting mitochondrial factor Smac/DIABLO as therapy for multiple myeloma (MM). Blood 113 17032924
2007 Smac mimetics and TNFalpha: a dangerous liaison? Cell 109 18022360
2007 S100A8/9 induces cell death via a novel, RAGE-independent pathway that involves selective release of Smac/DIABLO and Omi/HtrA2. Biochimica et biophysica acta 107 18060880
2010 Overcoming cancer cell resistance to Smac mimetic induced apoptosis by modulating cIAP-2 expression. Proceedings of the National Academy of Sciences of the United States of America 103 20547836
2008 Role of Smac/DIABLO in cancer progression. Journal of experimental & clinical cancer research : CR 96 18822137
2003 Fibroblast growth factor 2-mediated translational control of IAPs blocks mitochondrial release of Smac/DIABLO and apoptosis in small cell lung cancer cells. Molecular and cellular biology 93 14560006
2005 Solution structure of human survivin and its binding interface with Smac/Diablo. Biochemistry 92 15628841
2009 Smac mimetics as new cancer therapeutics. Anti-cancer drugs 89 19550293
2007 Regulation of mitochondrial Smac/DIABLO-selective release by survivin. Oncogene 82 17546047
2006 Altered expression of c-IAP1, survivin, and Smac contributes to chemotherapy resistance in thyroid cancer cells. Cancer research 82 16618750
2020 Targeting XIAP for Promoting Cancer Cell Death-The Story of ARTS and SMAC. Cells 79 32182843
2005 Mature DIABLO/Smac is produced by the IMP protease complex on the mitochondrial inner membrane. Molecular biology of the cell 77 15814844
2006 Livin promotes Smac/DIABLO degradation by ubiquitin-proteasome pathway. Cell death and differentiation 72 16729033
2003 Expression of Smac/DIABLO in ovarian carcinoma cells induces apoptosis via a caspase-9-mediated pathway. Experimental cell research 69 12749848
2004 Disturbed balance of expression between XIAP and Smac/DIABLO during tumour progression in renal cell carcinomas. British journal of cancer 68 15328523
2002 Reovirus-induced apoptosis requires mitochondrial release of Smac/DIABLO and involves reduction of cellular inhibitor of apoptosis protein levels. Journal of virology 68 12388702
2007 SMAC/Diablo mediates the proapoptotic function of PUMA by regulating PUMA-induced mitochondrial events. Oncogene 67 17237824
2004 Smac/Diablo antagonizes ubiquitin ligase activity of inhibitor of apoptosis proteins. The Journal of biological chemistry 67 15078891
2017 Smac mimetics and oncolytic viruses synergize in driving anticancer T-cell responses through complementary mechanisms. Nature communications 66 28839138
2003 Smac3, a novel Smac/DIABLO splicing variant, attenuates the stability and apoptosis-inhibiting activity of X-linked inhibitor of apoptosis protein. The Journal of biological chemistry 66 14523016
2016 RSL3 and Erastin differentially regulate redox signaling to promote Smac mimetic-induced cell death. Oncotarget 65 27588473
2010 Novel SMAC-mimetics synergistically stimulate melanoma cell death in combination with TRAIL and Bortezomib. British journal of cancer 63 20461078
2003 Interaction between XIAP and Smac/DIABLO in the mouse brain after transient focal cerebral ischemia. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 63 12973017
2014 Smac mimetics as IAP antagonists. Seminars in cell & developmental biology 62 25550219
2004 Neuronal apoptosis-inhibitory protein does not interact with Smac and requires ATP to bind caspase-9. The Journal of biological chemistry 61 15280366
2004 SMAC/Diablo-dependent apoptosis induced by nonsteroidal antiinflammatory drugs (NSAIDs) in colon cancer cells. Proceedings of the National Academy of Sciences of the United States of America 61 15557007
2008 Smac/DIABLO enhances the therapeutic potential of chemotherapeutic drugs and irradiation, and sensitizes TRAIL-resistant breast cancer cells. Molecular cancer 60 18590557
2017 Smac Mimetics to Therapeutically Target IAP Proteins in Cancer. International review of cell and molecular biology 59 28215531
2012 Structural basis for recognition of H3T3ph and Smac/DIABLO N-terminal peptides by human Survivin. Structure (London, England : 1993) 58 22244766
2003 Cephalostatin 1 selectively triggers the release of Smac/DIABLO and subsequent apoptosis that is characterized by an increased density of the mitochondrial matrix. Cancer research 57 14695204
2016 A Bak-dependent mitochondrial amplification step contributes to Smac mimetic/glucocorticoid-induced necroptosis. Cell death and differentiation 54 27834956
2003 Role of Smac in human leukaemic cell apoptosis and proliferation. Oncogene 53 12642862
2023 Structural basis for regulation of apoptosis and autophagy by the BIRC6/SMAC complex. Science (New York, N.Y.) 52 36758105
2005 The c-SMAC: sorting it all out (or in). The Journal of cell biology 50 16009722
2003 A novel ubiquitin fusion system bypasses the mitochondria and generates biologically active Smac/DIABLO. The Journal of biological chemistry 49 12511567
2005 Smac/DIABLO and cytochrome c are released from mitochondria through a similar mechanism during UV-induced apoptosis. Apoptosis : an international journal on programmed cell death 48 15843890
2020 SMAC mimetics and RIPK inhibitors as therapeutics for chronic inflammatory diseases. Science signaling 47 32071170
2013 Smac-mimetic-induced epithelial cell death reduces the growth of renal cysts. Journal of the American Society of Nephrology : JASN 47 23990677
2011 SMAC mimetic BV6 induces cell death in monocytes and maturation of monocyte-derived dendritic cells. PloS one 47 21738708
2003 Immunohistochemical analysis of Smac/DIABLO expression in human carcinomas and sarcomas. APMIS : acta pathologica, microbiologica, et immunologica Scandinavica 47 12752217
2005 Survivin interacts with Smac/DIABLO in ovarian carcinoma cells but is redundant in Smac-mediated apoptosis. Experimental cell research 46 15541727
2002 Promotion of photodynamic therapy-induced apoptosis by the mitochondrial protein Smac/DIABLO: dependence on Bax. Photochemistry and photobiology 45 12194220
2020 Caspase-8 loss radiosensitizes head and neck squamous cell carcinoma to SMAC mimetic-induced necroptosis. JCI insight 43 33108350
2020 Targeting triple-negative breast cancers with the Smac-mimetic birinapant. Cell death and differentiation 41 32341449
2015 Bax/Bak-dependent, Drp1-independent Targeting of X-linked Inhibitor of Apoptosis Protein (XIAP) into Inner Mitochondrial Compartments Counteracts Smac/DIABLO-dependent Effector Caspase Activation. The Journal of biological chemistry 40 26134559
2004 Oxidative stress is associated with XIAP and Smac/DIABLO signaling pathways in mouse brains after transient focal cerebral ischemia. Stroke 39 15118177
2020 Potency and Selectivity of SMAC/DIABLO Mimetics in Solid Tumor Therapy. Cells 38 32325691
2023 Structural basis for SMAC-mediated antagonism of caspase inhibition by the giant ubiquitin ligase BIRC6. Science (New York, N.Y.) 37 36758106
2020 OTUD7B suppresses Smac mimetic-induced lung cancer cell invasion and migration via deubiquitinating TRAF3. Journal of experimental & clinical cancer research : CR 37 33198776
2009 Clinical significance of Smac/DIABLO expression in colorectal cancer. Oncology reports 37 19148507
2015 Benzophenone 1 induced photogenotoxicity and apoptosis via release of cytochrome c and Smac/DIABLO at environmental UV radiation. Toxicology letters 36 26440554
2006 Novel link between E2F1 and Smac/DIABLO: proapoptotic Smac/DIABLO is transcriptionally upregulated by E2F1. Nucleic acids research 36 16617145
2017 Smac mimetics and type II interferon synergistically induce necroptosis in various cancer cell lines. Cancer letters 35 28923396
2006 Inhibition of caspase-8 attenuates neuronal death induced by limbic seizures in a cytochrome c-dependent and Smac/DIABLO-independent way. Brain research 35 16774749
2018 Regulation of Apoptosis and Radiation Sensitization in Lung Cancer Cells via the Sirt1/NF-κB/Smac Pathway. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 33 30016782
2017 A New Role for the Mitochondrial Pro-apoptotic Protein SMAC/Diablo in Phospholipid Synthesis Associated with Tumorigenesis. Molecular therapy : the journal of the American Society of Gene Therapy 33 29396267
2020 SMAC mimetics induce autophagy-dependent apoptosis of HIV-1-infected macrophages. Cell death & disease 32 32719312
2011 Caspase-3 deficiency reveals a physiologic role for Smac/DIABLO in regulating programmed cell death. Cell death and differentiation 32 21597464
2011 Functional mutation of SMAC/DIABLO, encoding a mitochondrial proapoptotic protein, causes human progressive hearing loss DFNA64. American journal of human genetics 32 21722859
2010 Smac/DIABLO release from mitochondria and XIAP inhibition are essential to limit clonogenicity of Type I tumor cells after TRAIL receptor stimulation. Cell death and differentiation 32 20395960
2005 Regulation of XIAP and Smac/DIABLO in the rat hippocampus following transient forebrain ischemia. Neurochemistry international 32 15567514
2016 MiR-24-BIM-Smac/DIABLO axis controls the sensitivity to doxorubicin treatment in osteosarcoma. Scientific reports 31 27681638
2012 Smac: Its role in apoptosis induction and use in lung cancer diagnosis and treatment. Cancer letters 31 22227574
2021 BAX and SMAC regulate bistable properties of the apoptotic caspase system. Scientific reports 30 33558564
2015 Smac mimetic and oleanolic acid synergize to induce cell death in human hepatocellular carcinoma cells. Cancer letters 30 25917078
2003 Expression of Smac/Diablo in tubular epithelial cells and during acute renal failure. Kidney international. Supplement 30 12969128
2005 Role of Smac/DIABLO in hydrogen peroxide-induced apoptosis in C2C12 myogenic cells. Free radical biology & medicine 28 16085184
2003 Substrate cleavage by caspases generates protein fragments with Smac/Diablo-like activities. Cell death and differentiation 28 14576775
2012 Proinflammatory characteristics of SMAC/DIABLO-induced cell death in antitumor therapy. Cancer research 27 22379024
2007 Disturbed expression of the apoptosis regulators XIAP, XAF1, and Smac/DIABLO in gastric adenocarcinomas. Diagnostic molecular pathology : the American journal of surgical pathology, part B 27 17471152
2007 Transfection of Smac/DIABLO sensitizes drug-resistant tumor cells to TRAIL or paclitaxel-induced apoptosis in vitro. Pharmacological research 27 18029193
2019 SMAC mimetics as potential cancer therapeutics in myeloid malignancies. British journal of haematology 26 30836448
2019 Smac mimetics LCL161 and GDC-0152 inhibit osteosarcoma growth and metastasis in mice. BMC cancer 26 31521127
2014 Molecular pathways: targeting death receptors and smac mimetics. Clinical cancer research : an official journal of the American Association for Cancer Research 26 24824309
2009 Myc down-regulation affects cyclin D1/cdk4 activity and induces apoptosis via Smac/Diablo pathway in an astrocytoma cell line. Cell proliferation 25 19143767
2004 Direct interaction of Smac with NADE promotes TRAIL-induced apoptosis. Biochemical and biophysical research communications 25 15178455

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