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)

Fas/APO-1 and p55 tumor necrosis factor (TNF) receptor (p55-R) activate cellular mechanisms that result in cell death. Upon activation of these receptors, Fas/APO-1 binds a protein called MORT1 (or FADD) and p55-R binds a protein called TRADD. MORT1 and TRADD can also bind to each other. We have cloned a novel protein, MACH, that binds to MORT1. This protein exists in multiple isoforms, some of which contain a region that has proteolytic activity and shows marked sequence homology to proteases of the ICE/CED-3 family. Cellular expression of the proteolytic MACH isoforms results in cell death. Expression of MACH isoforms that contain an incomplete ICE/CED-3 region provides effective protection against the cytotoxicity induced by Fas/APO-1 or p55-R triggering. These findings suggest that MACH is the most upstream enzymatic component in the Fas/APO-1- and p55-R-induced cell death signaling cascades.
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PMID:Involvement of MACH, a novel MORT1/FADD-interacting protease, in Fas/APO-1- and TNF receptor-induced cell death. 868 76

The ability of ligands of the tumor necrosis factor (TNF) family to induce death of cells independently of new protein synthesis provides a unique approach to molecular analysis of programmed cell death mechanisms. Sequential analysis of the protein-protein interactions by which these receptors signal, allows identification of specific molecules that participate in the cell death process and unequivocal definition of cause-effect relationships between them. Several receptors of this family, with structurally unrelated intracellular domains, have the ability to trigger cell death. some intracellular proteins that bind to the receptors and participate in the induction of their effects have been identified. Association of the Fas/APO1-interacting protein MORT1/FADD with the p55 TNF receptor-interacting protein TRADD, and the association of both MORT1/FADD and TRADD with a third protein, RIP, provide potential cross-talk mechanisms between Fas/APO1 and the p55 TNF receptor. TRAF2, a cytoplasmic protein that binds to the p75 TNF receptor, as well as to several other receptors of the TNF/NGF family, also binds to TRADD, thus further extending the range of receptors of this family that can share common signaling mechanisms. The N-terminal part of MORT1/FADD binds to a protease of the CED3/ICE family, MACH alpha. Activation of MACH alpha by the TNF/NGF receptors appears to be the most upstream enzymatic activity in the cascade of signaling for cell death.
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PMID:Exploring cell death mechanisms by analyzing signaling cascades of the TNF/NGF receptor family. 895 Apr 72

The pivotal discovery that Fas-associated death domain protein (FADD) interleukin-1beta-converting enzyme (FLICE)/MACH was recruited to the CD95 signaling complex by virtue of its ability to bind the adapter molecule FADD established that this protease has a role in initiating the death pathway (Boldin, M. P., Goncharov, T. M. , Goltsev, Y. V., and Wallach, D. (1996) Cell 85, 803-815; Muzio, M., Chinnaiyan, A. M., Kischkel, K. C., O'Rourke, K., Shevchenko, A., Ni, J., Scaffidi, C., Bretz, J. D., Zhang, M., Gentz, R., Mann, M., Krammer, P. H., Peter, M. E., and Dixit, V. M. (1996) Cell 85, 817-827). In this report, we describe the cloning and characterization of a new member of the caspase family, a homologue of FLICE/MACH, and Mch4. Since the overall architecture and function of this molecule is similar to that of FLICE, it has been designated FLICE2. Importantly, the carboxyl-terminal half of the small catalytic subunit that includes amino acids predicted to be involved in substrate binding is distinct. We show that the pro-domain of FLICE2 encodes a functional death effector domain that binds to the corresponding domain in the adapter molecule FADD. Consistent with this finding, FLICE2 is recruited to both the CD95 and p55 tumor necrosis factor receptor signaling complexes in a FADD-dependent manner. A functional role for FLICE2 is suggested by the finding that an active site mutant of FLICE2 inhibits CD95 and tumor necrosis factor receptor-mediated apoptosis. FLICE2 is therefore involved in CD95 and p55 signal transduction.
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PMID:Fas-associated death domain protein interleukin-1beta-converting enzyme 2 (FLICE2), an ICE/Ced-3 homologue, is proximally involved in CD95- and p55-mediated death signaling. 904 86

CASP-8 and CASP-10, members of a cysteine protease family that participates in apoptosis, interact with MORT1/FADD, an adapter protein in the CD120a (p55 tumor necrosis factor receptor), and CD95 (Fas/Apo-1) death-inducing signaling pathways, through a shared N-terminal sequence motif, the death effector domain. We report cloning of two splice variants of a novel protein, CASH, that contain two N-terminal death effector domains and can bind through them to each other, to MORT1/FADD, to CASP-8, and to CASP-10. The unique C-terminal part of the longer variant shows marked sequence homology to the caspase protease region yet lacks several of the conserved caspase active site residues, suggesting that it is devoid of cysteine protease activity. Overexpression of the short CASH splice variant strongly inhibited cytotoxicity induction by CD120a and CD95. Expression of the longer variant, while inhibiting cytotoxicity in HeLa cells, had a marked cytocidal effect in 293 cells that could be shown to involve its protease homology region. The findings suggest that CASH acts as an attenuator and/or initiator in CD95 and CD120a signaling for cell death.
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PMID:CASH, a novel caspase homologue with death effector domains. 928 91

Sphingomyelinase (SMase) activation and ceramide generation have emerged as an important signaling pathway transducing diverse biological effects of cytokine receptors like p55 tumor necrosis factor (TNF) receptor or Fas. Here we describe the TNF-dependent activation of acid SMase (A-SMase) through the p55 TNF receptor-associated proteins TRADD and FADD. Overexpression of TRADD and FADD in 293 cells did not change basal activity of A-SMase but enhanced TNF-induced stimulation of A-SMase. Other TNF R55-associated proteins like TRAF2 and RIP, which were reported to mediate TNF R55-mediated activation of nuclear factor kappaB, did not affect activation of A-SMase. Caspase inhibitors markedly reduced A-SMase activity, suggesting the involvement of an ICE-like protease in TRADD/FADD-mediated activation of A-SMase. Overexpression of caspase-8/a (FLICE/MACH) or caspase-10/b (FLICE2) did not change A-SMase activity, suggesting that TRADD/FADD-mediated activation of A-SMase involves a yet to be defined caspase-like protease distinct from caspase-8/a or -10/b.
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PMID:TNF receptor death domain-associated proteins TRADD and FADD signal activation of acid sphingomyelinase. 948 30

Treatment with NGF causes long-term cultures of oligodendrocytes to die via a yet undefined mechanism mediated by the p75 neurotrophin receptor. The p75 receptor belongs to the TNF receptor superfamily of molecules, which includes Fas and p55 TNF receptors. The Fas and TNF receptors use adaptor molecules to recruit and activate caspase-8 to the receptor. Using a combination of immunohistochemical and Western blotting assays, we have examined caspase activity during NGF-induced apoptosis. Interestingly, although caspase-1 [interleukin-1beta-converting enzyme (ICE)], caspase-2, caspase-3, and caspase-8 were expressed in oligodendrocytes, only caspase-1, -2, and -3 were activated after NGF treatment, whereas caspase-8 was not. These data suggest that the mechanism of apoptosis by NGF through the p75 receptor is different from TNF and Fas-mediated killing. gamma Radiation of oligodendrocytes also activated a similar subset of caspases as NGF, indicating that NGF-induced oligodendrocyte apoptosis uses a similar cell death execution mechanism as injury models. This consolidates a potential role of the p75 neurotrophin receptor during stress and inflammatory conditions.
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PMID:Oligodendrocyte apoptosis mediated by caspase activation. 1019 21

The B subunit of Escherichia coli heat-labile enterotoxin (EtxB) is a potent immunomodulatory molecule capable of treating and preventing autoimmune disease. These properties result from its ability to bind to glycolipid receptors, principally G(M1) ganglioside, and modulate immune cell function. EtxB receptor binding causes B cell activation, modulates monocyte cytokine secretion and triggers apoptosis of CD8+ T cells. These wide-ranging effects suggest that B subunit receptor interaction triggers signaling events affecting cellular differentiation. We have investigated the processes by which EtxB induces CD8+ T cell apoptosis. We show that receptor interaction by EtxB activates caspase-3 in CD8+ but not in CD4+ T cells. Inhibition of caspase-3 blocks the apoptotic process. EtxB induces the activation of NF-kappaB in both CD8+ and CD4+ T cells. The findings that (i) SN50, a peptide inhibitor of NF-kappaB nuclear translocation, prevents caspase-3 activation and subsequent apoptosis, and (ii) CD8+CD4- thymocytes from transgenic mice expressing a dominant-negative form of the IkappaBalpha protein were markedly less susceptible to EtxB-induced apoptosis than cells from wild-type mice, indicate that NF-kappaB is important in the induction of the apoptotic pathway. Further investigations revealed that while caspase-8 activity is detected concomitant to caspase-3, caspase-9 activation, following mitochondrial cytochrome c release, is detectable later on. These observations are consistent with death receptor-mediated signaling, however, experiments using lpr/lpr and p55 TNFR -/- mice rule out the involvement of Fas and the p55 TNF receptor, respectively. The data therefore indicate that EtxB-mediated apoptosis occurs via a novel pathway involving NF-kappaB.
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PMID:CD8+ T cell apoptosis induced by Escherichia coli heat-labile enterotoxin B subunit occurs via a novel pathway involving NF-kappaB-dependent caspase activation. 1211 57

Tumor necrosis factor-alpha (TNF-a) is produced by alveolar macrophages (AM) in response to bleomycin (BLM) exposure. This cytokine has been linked to BLM-induced pulmonary inflammation, an early drug effect, and to lung fibrosis, the ultimate toxic effect of BLM. The present study was carried out to study the time dependence of apoptotic signaling pathways and the potential roles of TNF receptors in BLM-induced AM apoptosis. Male Sprague-Dawley rats were exposed to saline or BLM (1 mg/kg) by intratracheal instillation. At 1, 3, or 7 d postexposure, AM were isolated by bronchoalveolar (BAL) lavage and evaluated for apoptosis by ELISA. The release of cytochrome c from mitochrondria, the activation of caspase-3, -8, and -9, the cleavage of nuclear poly(ADP-ribose) polymerase (PARP), and the expression of TNF receptors (TNF-R1/p55 and TNF-R2/p75), TNF-R-associated factor 2 (TRAF2), and cellular inhibitor of apoptosis 1 (c-IAP1) were determined by immunoblotting. The results showed that BLM exposure induced AM apoptosis, with the highest apoptotic effect occurring at 1 d after exposure and gradually decreasing at 3 and 7 d postexposure, but still remaining significantly above the control level. The maximal translocation of cytochromec from mitochondria into the cytosol was observed at 1 d postexposure, whereas the activation of caspase-9 and caspase-3 and caspase-3-dependent cleavage of PARP was found to reach a peak level at 3 d postexposure. BLM exposure had no marked effect on AM expression of TNF-R1 or caspase-8 activation, but significantly increased the expression of TNF-R2 that was accompanied by a rise in c-IAP1 and a decrease in TRAF2. This induction of TNF-R2 by BLM was significant on d 1 and increased with greater exposure time. In vitro studies showed that pretreatment of naive AM with a TNF-R2 antibody significantly inhibited BLM-induced caspase-3 activity and apoptosis. These results suggest that BLM-induced apoptosis involves multiple pathways in a time-dependent manner. Since maximal BLM-induced AM apoptosis (1 d postexposure) preceded maximal changes in caspase-9 and -3 (3 d postexposure), it is possible that a caspase-independent mechanism is involved in this initial response. These results indicate that the sustained expression of TNF-R2 in AM by BLM exposure may sensitize these cells to TNF-a-mediated toxicity.
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PMID:Time-dependent apoptosis of alveolar macrophages from rats exposed to bleomycin: involvement of tnf receptor 2. 1537 Dec 38

This study was designed to determine the role of tumor necrosis factor-alpha (TNFalpha) in apoptosis observed in the myocardium and limbic system after myocardial ischemia. PEG sTNFRI, a recombinant, human, soluble p55 Type 1 TNF receptor (3 mg/kg) or vehicle (saline) was administered s.c. to male Sprague-Dawley rats on days 5, 3 and 1 before myocardial ischemia. The animals were then subjected, under anesthesia, to left anterior descending coronary artery occlusion for 40 min, followed by 15-min or 72-h reperfusion. Caspase-3 and -8 activities as well as terminal dUTP nick-end labelling-positive cells were examined in the myocardium (subendocardial and subepicardial regions), lateral (LA) and medial amygdala (MA) and hippocampus (CA1, CA3, dentate gyrus (DG)). After 15 min of reperfusion, the subendocardial and CA1 regions presented an increase in caspase-3 activity, whereas caspase-8 activity appeared to be augmented in the DG. PEG sTNFRI inhibited caspase-8 activation in the DG. After 72 h of reperfusion, plasma TNFalpha levels were reduced in the treated groups. The DG, CA1, CA3 and MA showed an increment of caspase-8 activity, which was reversed by PEG sTNFRI, except in the MA. Furthermore, caspase-3 activity was increased in the CA1, DG, LA and MA. These results indicate that TNFalpha contributes to apoptosis via activation of the extrinsic pathway in the limbic system after myocardial infarction, which is not the case in the myocardium.
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PMID:Tumor necrosis factor-alpha participates in apoptosis in the limbic system after myocardial infarction. 1972 97

The ability of the alveolar epithelium to prevent and resolve pulmonary edema is a crucial determinant of morbidity and mortality in acute lung injury (ALI). TNF has been implicated in ALI pathogenesis, but the precise mechanisms remain undetermined. We evaluated the role of TNF signaling in pulmonary edema formation in a clinically relevant mouse model of ALI induced by acid aspiration and investigated the effects of TNF p55 receptor deletion, caspase-8 inhibition, and alveolar macrophage depletion on alveolar epithelial function. We found that TNF plays a central role in the development of pulmonary edema in ALI through activation of p55-mediated death signaling, rather than through previously well-characterized p55-mediated proinflammatory signaling. Acid aspiration produced pulmonary edema with significant alveolar epithelial dysfunction, as determined by alveolar fluid clearance (AFC) and intra-alveolar levels of the receptor for advanced glycation end-products. The impairment of AFC was strongly correlated with lung caspase-8 activation, which was localized to type 1 alveolar epithelial cells by flow cytometric analysis. p55-deficient mice displayed markedly attenuated injury, with improved AFC and reduced caspase-8 activity but no differences in downstream cytokine/chemokine production and neutrophil recruitment. Caspase-8 inhibition significantly improved AFC and oxygenation, whereas depletion of alveolar macrophages attenuated epithelial dysfunction with reduced TNF production and caspase-8 activity. These results provide in vivo evidence for a novel role for TNF p55 receptor-mediated caspase-8 signaling, without substantial apoptotic cell death, in triggering alveolar epithelial dysfunction and determining the early pathophysiology of ALI. Blockade of TNF-induced death signaling may provide an effective early-phase strategy for ALI.
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PMID:TNF-induced death signaling triggers alveolar epithelial dysfunction in acute lung injury. 2348 22


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