Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.61 (caspase-8)
 6,833 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

FADD/MORT1 is a death domain (DD)-containing adaptor/signaling molecule that interacts with the intracellular DD of FAS/APO-I (CD95) and tumor necrosis factor receptor 1 and the prodomain of caspase-8 (Mch5/MACH/FLICE). FADD engagement of caspase-8 presumably activates this caspase and leads to apoptosis. Another DD-containing adaptor/signaling molecule, CRADD, was identified and was shown to induce apoptosis. CRADD has a dual-domain structure similar to that of FADD. It has an NH2-terminal caspase homology domain that interacts with caspase-2 and a COOH-terminal DD that interacts with RIP. CRADD is constitutively expressed in many tissues and thus could play a role in regulating apoptosis in mammalian cells.
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PMID:CRADD, a novel human apoptotic adaptor molecule for caspase-2, and FasL/tumor necrosis factor receptor-interacting protein RIP. 904 36

We have identified a human Bcl-2-interacting protein, p28 Bap31. It is a 28-kD (p28) polytopic integral protein of the endoplasmic reticulum whose COOH-terminal cytosolic region contains overlapping predicted leucine zipper and weak death effector homology domains, flanked on either side by identical caspase recognition sites. In cotransfected 293T cells, p28 is part of a complex that includes Bcl-2/Bcl-XL and procaspase-8 (pro-FLICE). Bax, a pro-apoptotic member of the Bcl-2 family, does not associate with the complex; however, it prevents Bcl-2 from doing so. In the absence (but not presence) of elevated Bcl-2 levels, apoptotic signaling by adenovirus E1A oncoproteins promote cleavage of p28 at the two caspase recognition sites. Purified caspase-8 (FLICE/MACH/Mch5) and caspase-1(ICE), but not caspase-3 (CPP32/apopain/ Yama), efficiently catalyze this reaction in vitro. The resulting NH2-terminal p20 fragment induces apoptosis when expressed ectopically in otherwise normal cells. Taken together, the results suggest that p28 Bap31 is part of a complex in the endoplasmic reticulum that mechanically bridges an apoptosis-initiating caspase, like procaspase-8, with the anti-apoptotic regulator Bcl-2 or Bcl-XL. This raises the possibility that the p28 complex contributes to the regulation of procaspase-8 or a related caspase in response to E1A, dependent on the status of the Bcl-2 setpoint within the complex.
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PMID:p28 Bap31, a Bcl-2/Bcl-XL- and procaspase-8-associated protein in the endoplasmic reticulum. 933 38

We report here the identification and characterization of a new member of the mouse caspase family, named caspase-14. Northern blot analysis of mRNA from various tissues with caspase-14-specific probe showed a major transcript size of approximately 2.4 kb and variant transcripts of 2.0 kb and 1.5 kb. The major transcript is detected mainly in the liver and to a lesser extent in the brain and kidney. Caspase-14 cDNA encodes a 257-amino acid-long protein that has significant homology to other members of the caspase family. Like other caspases, caspase-14 has a conserved active site, pentapeptide QACRG. However, it lacks an NH2-terminal prodomain or a caspase recruitment domain, suggesting that it could be a downstream caspase that depends on other initiator caspases for activation. Consistent with this, procaspase-14 can be processed in vitro by the death receptor-associated caspase-8 and caspase-10 but not other caspases, and in vivo after stimulation of cells with anti-Fas agonist antibody or Tumor Necrosis Factor-Related Apoptosis Inducing Ligand. Furthermore, procaspase-14 can be cleaved by granzyme B. These observations suggest that caspase-14 may play a role in death receptor and granzyme B-induced apoptosis.
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PMID:Identification and characterization of murine caspase-14, a new member of the caspase family. 982 33

To identify essential components of the Fas-induced apoptotic signaling pathway, Jurkat T lymphocytes were chemically mutagenized and selected for clones that were resistant to Fas-induced apoptosis. We obtained five cell lines that contain mutations in the adaptor FADD. All five cell lines did not express FADD by immunoblot analysis and were completely resistant to Fas-induced death. Complementation of the FADD mutant cell lines with wild-type FADD restored Fas-mediated apoptosis. Fas activation of caspase-2, caspase-3, caspase-7, and caspase-8 and the proteolytic cleavage of substrates such as BID, protein kinase Cdelta, and poly(ADP-ribose) polymerase were completely defective in the FADD mutant cell lines. In addition, Fas activation of the stress kinases p38 and c-Jun NH2 kinase and the generation of ceramide in response to Fas ligation were blocked in the FADD mutant cell lines. These data indicate that FADD is essential for multiple signaling events downstream of Fas.
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PMID:FADD is required for multiple signaling events downstream of the receptor Fas. 1061 4

We reported previously that a synthetic compound, MT-21, induced apoptosis by activating c-Jun-NH2-terminal kinase via the Krs/MST protein, which is activated by caspase-3 cleavage dependent on reactive oxygen species production. Here we examine the activation mechanism of caspase-3, an important cysteine aspartic protease, during MT-21-induced apoptosis. We found that MT-21 activated caspase-3 via caspase-9, but not via caspase-8. In addition, MT-21 induced the release of cytochrome c from the mitochondria that is necessary to activate caspase-9, and this release occurred before a change in membrane potential. This initiation process of MT-21-induced apoptosis was suppressed by overexpression of Bcl-2, which is known to prevent cells from undergoing apoptosis in response to a variety of stimuli. Moreover, when we treated mitochondria isolated from the cells with MT-21, the direct release of cytochrome c from the mitochondria was observed, whereas this effect was not observed in the mitochondria isolated from cells that overexpressed Bcl-2. Other apoptosis-inducing agents known to induce apoptosis via cytochrome c release from the mitochondria failed to release cytochrome c directly from isolated mitochondria. These findings indicate that MT-21 is a possible candidate antitumor agent that is able to induce apoptosis via the direct release of cytochrome c from the mitochondria.
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PMID:MT-21 is a synthetic apoptosis inducer that directly induces cytochrome c release from mitochondria. 1101 50

Persistent c-Jun NH2-terminal kinase (JNK) activation induces cell death. Different mechanisms are ascribed to JNK-induced cell death. Most of the JNK-apoptosis studies employ stress stimuli known to activate kinases other than JNK. Here we used overexpression of mitogen-activated protein kinase kinase 7 (MKK7) to activate selectively JNK in T lymphoma Jurkat cells. Similar to that reported previously, Fas ligand (FasL) expression was up-regulated by JNK activation. Dominant negative-FADD and caspase-8 inhibitor benzyloxycarbonyl-Ile-Glu-Thr-Asp effectively inhibited MKK7-induced cell death, supporting a major involvement of FADD cascade. However, MKK7-induced cell death was not prevented by antagonist antibody ZB4 and Fas-Fc, indicating that Fas-FasL interaction is minimally involved. Confocal microscopy revealed that persistent JNK activation led to clustering of Fas. Our results suggest that, in contrast to that reported previously, JNK alone-induced death in Jurkat cells is FADD-dependent but is not triggered by Fas-FasL interaction.
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PMID:c-Jun NH2-terminal kinase activation leads to a FADD-dependent but Fas ligand-independent cell death in Jurkat T cells. 1110 58

In the absence of an apoptotic signal, BAX adopts a conformation that constrains the protein from integrating into mitochondrial membranes. Here, we show that caspases, including caspase-8, can initiate BAX insertion into mitochondria in vivo and in vitro. The cleavage product of caspase-8, tBID, induced insertion of BAX into mitochondria in vivo, and reconstitution in vitro showed that tBID, either directly or indirectly, relieved inhibition of the BAX transmembrane signal-anchor by the NH2-terminal domain, resulting in integration of BAX into mitochondrial membrane. In contrast to these findings, however, Bid-null mouse embryo fibroblasts supported Bax insertion into mitochondria in response to death signaling by either TNFalpha or E1A, despite the fact that cytochrome c release from the organelle was inhibited. We conclude, therefore, that a parallel Bid-independent pathway exists in these cells for mitochondrial insertion of Bax and that, in the absence of Bid, cytochrome c release can be uncoupled from Bax membrane insertion.
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PMID:BID-dependent and BID-independent pathways for BAX insertion into mitochondria. 1113 84

Apoptosis induction may be a mechanism mediating the anticancer activity of selenium. Our earlier work indicated that distinct cell death pathways are likely involved in apoptosis induced by the CH3SeH and the hydrogen selenide pools of selenium metabolites. To explore the role of caspases in cancer cell apoptosis induced by selenium, we examined the involvement of these molecules in the death of the DU-145 human prostate carcinoma cells induced by methylseleninic acid (MSeA), a novel penultimate precursor of the putative critical anticancer metabolite CH3SeH. Sodium selenite, a representative of the genotoxic selenium pool, was used as a reference for comparison. The results show that MSeA-induced apoptosis was accompanied by the activation of multiple caspases (caspase-3, -7, -8, and -9), mitochondrial release of cytochrome c (CC), poly(ADP-ribose) polymerase (PARP) cleavage, and DNA fragmentation. In contrast, selenite-induced apoptotic DNA fragmentation was observed in the absence of these changes, but was associated with the phosphorylation of c-Jun-NH2-terminal kinase 1/2 and p38 mitogen-activated protein kinase/stress-activated protein kinase 2. A general caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-(OMe) fluoromethyl ketone, blocked MSeA-induced cleavage of procaspases and PARP, CC release, and DNA nucleosomal fragmentation, but did not prevent cell detachment. Furthermore, PARP cleavage and caspase activation were confined exclusively to detached cells, indicating that MSeA induction of cell detachment was a prerequisite for caspase activation and apoptosis execution. This process therefore resembled "anoikis," a special mode of apoptosis induction in which adherent cells lose contact with the extracellular matrix. Additional experiments with irreversible caspase inhibitors show that MSeA-induced anoikis involved caspase-3- and -7-mediated PARP cleavage that was initiated by caspase-8 and probably amplified through CC-caspase-9 activation and a feedback activation loop from caspase-3. Taken together, the data support a methyl selenium-specific induction of DU-145 cell apoptosis that involves cell detachment as a prerequisite (anoikis) and is executed principally through caspase-8 activation and its cross-talk with multiple caspases.
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PMID:Caspases as key executors of methyl selenium-induced apoptosis (anoikis) of DU-145 prostate cancer cells. 1130 88

Keratin 8 and 18 (K8/18) are the major components of intermediate filament (IF) proteins of simple or single-layered epithelia. Recent data show that normal and malignant epithelial cells deficient in K8/18 are nearly 100 times more sensitive to tumor necrosis factor (TNF)-induced cell death. We have now identified human TNF receptor type 1 (TNFR1)-associated death domain protein (TRADD) to be the K18-interacting protein. Among IF proteins tested in two-hybrid systems, TRADD specifically bound K18 and K14, type I (acidic) keratins. The COOH-terminal region of TRADD interacted with the coil Ia of the rod domain of K18. Endogenous TRADD coimmunoprecipitated with K18, and colocalized with K8/18 filaments in human mammary epithelial cells. Overexpression of the NH2 terminus (amino acids 1-270) of K18 containing the TRADD-binding domain as well as overexpression of K8/18 in SW13 cells, which are devoid of keratins, rendered the cells more resistant to killing by TNF. We also showed that overexpressed NH2 termini of K18 and K8/18 were associated with endogenous TRADD in SW13 cells, resulting in the inhibition of caspase-8 activation. These results indicate that K18 may sequester TRADD to attenuate interactions between TRADD and activated TNFR1 and moderate TNF-induced apoptosis in simple epithelial cells.
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PMID:Keratin attenuates tumor necrosis factor-induced cytotoxicity through association with TRADD. 1168 8

The SK-N-MC neuroblastoma cell line, which expresses surface tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors TRAIL-R2 and TRAIL-R4, was used as a model system to examine the effect of TRAIL on key intracellular pathways involved in the control of neuronal cell survival and apoptosis. TRAIL induced distinct short-term (1-60 min) and long-term (3-24 h) effects on the protein kinase B (PKB)/Akt (Akt), extracellular signal-regulated kinase (ERK), cAMP response element-binding protein (CREB), nuclear factor kappa B (NF-kappaB) and caspase pathways. TRAIL rapidly (from 20 min) induced the phosphorylation of Akt and ERK, but not of c-Jun NH2-terminal kinase (JNK). Moreover, TRAIL increased CREB phosphorylation and phospho-CREB DNA binding activity in a phosphatidylinositol 3-kinase (PI 3K)/Akt-dependent manner. At later time points (from 3 to 6 h onwards) TRAIL induced a progressive degradation of inhibitor of kappaB (IkappaB)beta and IkappaBepsilon, but not IkappaBalpha, coupled to the nuclear translocation of NF-kappaB and an increase in its DNA binding activity. In the same time frame, TRAIL started to activate caspase-8 and caspase-3, and to induce apoptosis. Remarkably, caspase-dependent cleavage of NF-kappaB family members as well as of Akt and CREB proteins, but not of ERK, became prominent at 24 h, a time point coincident with the peak of caspase-dependent apoptosis.
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PMID:Tumour necrosis factor-related apoptosis-inducing ligand sequentially activates pro-survival and pro-apoptotic pathways in SK-N-MC neuronal cells. 1280 32


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