Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report that the serine protease granzyme B (GrB), which is crucial for granule-mediated cell killing, initiates apoptosis in target cells by first maturing caspase-10. In addition, GrB has a limited capacity to mature other caspases and to cause cell death independently of the caspases. Compared with other members, GrB in vitro most efficiently processes caspase-7 and -10. In a human cell model, full maturation of caspase-7 does not occur unless caspase-10 is present. Furthermore, GrB matured caspase-3 with less efficiency than caspase-7 or caspase-10. With the caspases fully inactivated by peptidic inhibitors, GrB induced in Jurkat cells growth arrest and, over a delayed time period, cell death. Thus, the primary mechanism by which GrB initiates cell death is activation of the caspases through caspase-10. However, under circumstances where caspase-10 is absent or dysfunctional, GrB can act through secondary mechanisms including activation of other caspases and direct cell killing by cleavage of noncaspase substrates. The redundant functions of GrB ensure the effectiveness of granule-mediated cell killing, even in target cells that lack the expression or function (e.g., by mutation or a viral serpin) of one or more of the caspases, providing the host with overlapping safeguards against aberrantly replicating, nonself or virally infected cells.
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PMID:Granule-mediated killing: pathways for granzyme B-initiated apoptosis. 933 72

Apoptosis is a major form of cell death, characterized initially by a series of stereotypic morphological changes. In the nematode Caenorhabditis elegans, the gene ced-3 encodes a protein required for developmental cell death. Since the recognition that CED-3 has sequence identity with the mammalian cysteine protease interleukin-1 beta-converting enzyme (ICE), a family of at least 10 related cysteine proteases has been identified. These proteins are characterized by almost absolute specificity for aspartic acid in the P1 position. All the caspases (ICE-like proteases) contain a conserved QACXG (where X is R, Q or G) pentapeptide active-site motif. Capases are synthesized as inactive proenzymes comprising an N-terminal peptide (prodomain) together with one large and one small subunit. The crystal structures of both caspase-1 and caspase-3 show that the active enzyme is a heterotetramer, containing two small and two large subunits. Activation of caspases during apoptosis results in the cleavage of critical cellular substrates, including poly(ADP-ribose) polymerase and lamins, so precipitating the dramatic morphological changes of apoptosis. Apoptosis induced by CD95 (Fas/APO-1) and tumour necrosis factor activates caspase-8 (MACH/FLICE/Mch5), which contains an N-terminus with FADD (Fas-associating protein with death domain)-like death effector domains, so providing a direct link between cell death receptors and the caspases. The importance of caspase prodomains in the regulation of apoptosis is further highlighted by the recognition of adapter molecules, such as RAIDD [receptor-interacting protein (RIP)-associated ICH-1/CED-3-homologous protein with a death domain]/CRADD (caspase and RIP adapter with death domain), which binds to the prodomain of caspase-2 and recruits it to the signalling complex. Cells undergoing apoptosis following triggering of death receptors execute the death programme by activating a hierarchy of caspases, with caspase-8 and possibly caspase-10 being at or near the apex of this apoptotic cascade.
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PMID:Caspases: the executioners of apoptosis. 933 44

Although the commonly activated death protease caspase-3 appears not to be essential for apoptosis during development except in the brain, it was not shown whether substrates known to be cleaved by caspase-3 are still proteolyzed in its absence. We have addressed this question with MCF-7 breast carcinoma cells that we recently showed lack caspase-3 owing to the functional deletion of the CASP-3 gene. Tumor necrosis factor- or staurosporine-induced apoptosis of caspase-3-deficient MCF-7 cells resulted in cleavage of the death substrates PARP, Rb, PAK2, DNA-PKcs, gelsolin, and DFF-45, but not alpha-fodrin. In contrast, all these substrates including alpha-fodrin were cleaved in apoptotic HeLa cells expressing caspase-3. Introduction of CASP-3 cDNA, but not CASP-10 cDNA, into MCF-7 cells restored alpha-fodrin cleavage. In addition, tumor necrosis factor- or staurosporine-induced apoptosis of MCF-7 cells stably expressing pro-caspase-3 also resulted in alpha-fodrin cleavage. Although the specific caspase inhibitory peptides Z-VAD-fmk and Z-DEVD-fmk prevented apoptosis of MCF-7 cells, we were unable to detect activation of caspases 2 and 7, which are known to be inhibited by Z-DEVD-fmk. Together our results suggest that caspase-3 is essential for cleavage of alpha-fodrin, but dispensable for the cleavage of PARP, Rb, PAK2, DNA-PKcs, gelsolin, and DFF-45 and imply that one or more caspases other than caspases 2, 3, and 7 is activated and plays a crucial role in the cleavage of these substrates in MCF-7 cells.
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PMID:Caspase-3 is required for alpha-fodrin cleavage but dispensable for cleavage of other death substrates in apoptosis. 962 43

Caspases are a family of cysteine proteases related to interleukin-1 converting enzyme (ICE) and represent the effector arm of the cell death pathway. The zymogen form of all caspases is composed of a prodomain plus large and small catalytic subunits. Herein we report the characterization of a novel caspase, MICE (for mini-ICE), also designated caspase-14, that possesses an unusually short prodomain and is highly expressed in embryonic tissues but absent from all adult tissues examined. In contrast to the other short prodomain caspases (caspase-3, caspase-6, and caspase-7), MICE preferentially associates with large prodomain caspases, including caspase-1, caspase-2, caspase-4, caspase-8, and caspase-10. Also unlike the other short prodomain caspases, MICE was not processed by multiple death stimuli including activation of members of the tumor necrosis factor receptor family and expression of proapoptotic members of the bcl-2 family. Surprisingly, however, overexpression of MICE itself induced apoptosis in MCF7 human breast cancer cells, which was attenuated by traditional caspase inhibitors.
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PMID:Caspase-14 is a novel developmentally regulated protease. 979 75

Caspases (aspartate-specific cysteine proteases) play a critical role in the execution of the mammalian apoptotic program. To address the regulation of human caspase activation, we used the yeast Saccharomyces cerevisiae, which is devoid of endogenous caspases. The apical procaspases, -8beta and -10, were efficiently processed and activated in yeast. Although protease activity, per se, was insufficient to drive cell death, caspase-10 activity had little effect on cell viability, whereas expression of caspase-8beta was cytotoxic. This lethal phenotype was abrogated by co-expression of the pan-caspase inhibitor, baculovirus p35, and by mutation of the active site cysteine of procaspase-8beta. In contrast, autoactivation of the executioner caspase-3 and -6 zymogens was not detected. Procaspase-3 activation required co-expression of procaspase-8 or -10. Surprisingly, activation of procaspase-6 required proteolytic activities other than caspase-8, -10, or -3. Caspase-8beta or -10 activity was insufficient to catalyze the maturation of procaspase-6. Moreover, a constitutively active caspase-3, although cytotoxic in its own right, was unable to induce the processing of wild-type procaspase-6 and vice versa. These results distinguish sequential modes of activation for different caspases in vivo and establish a yeast model system to examine the regulation of caspase cascades. Moreover, the distinct terminal phenotypes induced by various caspases attest to differences in the cellular targets of these apoptotic proteases, which may be defined using this system.
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PMID:Cascades of mammalian caspase activation in the yeast Saccharomyces cerevisiae. 991 59

The antitumor effect of immuno- and chemotherapeutic agents is executed through stimulation of apoptotic programs in susceptible cells. Apoptosis induced in tumor cells requires activation of members of the caspase family of proteases. Deficient expression or activation of caspases may account in part for the failure of many current anticancer therapies. However, recent studies suggest that cell death can proceed in the absence of caspases. We investigated the susceptibility of human renal cell carcinoma (RCC) lines to two distinct modes of cell death, apoptosis and necrosis. RCC lines displayed almost complete resistance to apoptosis in response to the intracellular zinc chelator, N,N,N'N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), which instead induced dramatic accumulation of nonapoptotic necrotic cells. Conversely, TPEN was a potent inducer of apoptosis in caspase-competent normal kidney cells (NK-72) and Jurkat T lymphocytes. Resistance to apoptosis in RCC lines correlated with almost complete loss of caspase-3 expression and variable down-regulation of caspase-7, caspase-8, and caspase-10. These data may explain the resistance of RCC to drugs inducing apoptosis and have important consequences for further attempts to manipulate tumor cell death.
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PMID:Dead or dying: necrosis versus apoptosis in caspase-deficient human renal cell carcinoma. 1038 43

We have demonstrated that Apo-2 ligand (Apo-2L)/tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis of human prostate cancer PC-3, DU145, and LNCaP cells in a dose-dependent manner, with PC-3 cells displaying the greatest sensitivity to Apo-2L/TRAIL. Susceptibility of the prostate cancer cell types to Apo-2L/TRAIL-induced apoptosis did not appear to correlate with the levels of the Apo-2L/TRAIL receptors death receptor (DR) 4 (TRAIL receptor 1) or DR5 (TRAIL receptor 2), decoy receptor (DcR) 1 and DcR2, Flame-1, or the inhibitors of apoptosis proteins family of proteins. Apo-2L/TRAIL-induced apoptosis of PC-3 cells was associated with the processing of caspase-8, caspase-10, and the proapoptotic Bid protein, resulting in the cytosolic accumulation of cytochrome c as well as the processing of procaspase-9 and procaspase-3. Cotreatment with the caspase-8 inhibitor z-IETD-fmk or DR4:Fc significantly inhibited Apo-2L/TRAIL-induced apoptosis. Treatment with paclitaxel or taxotere increased DR4 and/or DR5 protein levels (up to 8-fold) without affecting the protein levels of DcR1 and DcR2, Apo-2L/TRAIL, Fas, or Fas ligand. Up-regulation of DR4 and DR5 was not preceded by the induction of their mRNA levels but was inhibited by cotreatment with cycloheximide. Importantly, sequential treatment of PC-3, DU145, and LNCaP cells with paclitaxel followed by Apo-2L/TRAIL induced significantly more apoptosis than Apo-2L/TRAIL treatment alone (P < 0.01). This was also associated with greater processing of procaspase-8 and Bid, as well as greater cytosolic accumulation of cytochrome c and the processing of caspase-3. These findings indicate that up-regulation of DR4 and DR5 protein levels by treatment with paclitaxel enhances subsequent Apo-2L/TRAIL-induced apoptosis of human prostate cancer cells.
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PMID:Pretreatment with paclitaxel enhances apo-2 ligand/tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis of prostate cancer cells by inducing death receptors 4 and 5 protein levels. 1121 79

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a TNF family member and potent apoptosis inducer. In contrast to TNF-alpha or Fas ligand, relatively little is known about the signaling events activated by TRAIL. In particular, the initial caspase(s) required for TRAIL-induced apoptosis remains to be determined Caspase-3-like protease but not caspase-1-like protease (YVADase) activity rapidly increased in HeLa cells in response to TRAIL treatment. The increase in protease activity correlated with the profile of apoptotic cell death that was inhibited by the pan-caspase inhibitor Z-VAD-fmk. In response to TRAIL, caspase-8, an initiator caspase in death receptor-mediated apoptosis, was activated within 1 h in association with Bid cleavage, cytochrome c release, caspase-3 activation, and DNA fragmentation factor 45 cleavage. Z-IETD-fmk, a caspase-8 inhibitor, completely blocked caspase-8 activation and resulted in inhibition of caspase-3 (a caspase-3-like protease) activation and apoptotic cell death. Overexpression of a caspase-8 dominant negative mutant inhibited apoptosis induced by TRAIL. Caspase-8-deficient Jurkat cells were resistant to both TRAIL and Fas-induced apoptosis, whereas wild-type Jurkat cells were susceptible to both TRAIL- and Fas-induced apoptosis. The caspase-8-reintro duced caspase-8-deficient Jurkat cells acquired normal susceptibility to both TRAIL and agonistic Fas antibody. Reverse transcription-PCR and sequence analyses have revealed that these caspase-8-deficient Jurkat cell express wild-type caspase-10. Therefore, our data indicate that caspase-8 is required for TRAIL-induced apoptosis and suggest that caspase-10 may play a minor role, if any, in TRAIL-induced apoptosis.
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PMID:Signaling events triggered by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL): caspase-8 is required for TRAIL-induced apoptosis. 1122 44

In this study, we investigated the sensitivity of Ewing's sarcoma family tumors (ESFTs) of children and adolescents to the tumor necrosis factor-related apoptosis-inducing Ligand (TRAIL). TRAIL binds to death receptors (DRs) DR4, DR5, DcR1, and DcR2. Either DR4 or DR5 can induce apoptosis, whereas DcR1 and DcR2 are considered inhibitory receptors. Nine of 10 ESFT cell lines, including several that were Fas resistant, underwent apoptosis with TRAIL through activation of caspase-10, capase-8 (FLICE), caspase-3, and caspase-9. In contrast to the Fas signaling pathway, caspase-10, but not caspase-8 or the Fas-associated death domain-containing molecule, was recruited to the TRAIL receptor-associated signaling complex. We found that 9 of 10 ESFT cell lines expressed both DR4 and DR5 by Western blotting, whereas the TRAIL-resistant line expressed only DR4. However, DR4 was absent from the cell surface in the resistant and two additional lines (three of five tested lines), suggesting that it may have been nonfunctional. On the contrary, DR5 was located on the cell surface in all four sensitive lines tested, being absent only from the cell surface of the resistant line that was also DR5-negative by Western blotting. In agreement with these findings, the resistance of the line was overcome by restoration of DR5 levels by transfection. Levels of DcR1 and DcR2 or levels of the FLICE-inhibitory protein (FLIP) did not correlate with TRAIL resistance, and protein synthesis inhibition did not sensitize the TRAIL-resistant line to TRAIL. Because these data suggested that sensitivity of ESFTs to TRAIL was mainly based on the presence of DR4/DR5, we investigated the presence of these receptors in 32 ESFT tissue sections by immunohistochemistry. We found that 23 of 32 tumor tissues (72%) expressed both receptors, 8 of 32 (25%) expressed one receptor only, and 1 was negative for both. Our finding of wide expression of DR4/DR5 in ESFT in vivo, in combination with their high sensitivity to TRAIL in vitro and the reported lack of toxicity of TRAIL in mice and monkeys, suggests that TRAIL may be a novel effective agent in the treatment of ESFTs.
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PMID:Ewing's sarcoma family tumors are sensitive to tumor necrosis factor-related apoptosis-inducing ligand and express death receptor 4 and death receptor 5. 1128 51

Tumor necrosis (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines that promotes apoptosis. TRAIL induces apoptosis via death receptors (DR4 and DR5) in a wide variety of tumor cells but not in normal cells. The objectives of this study are to investigate the intracellular mechanisms by which TRAIL induces apoptosis. The death receptor Fas, upon ligand binding, trimerizes and recruits the adaptor protein FADD through the cytoplasmic death domain of Fas. FADD then binds and activates procaspase-8. It is unclear whether FADD is required for TRAIL-induced apoptosis. Here we show that the signaling complex of DR4/DR5 is assembled in response to TRAIL binding. FADD and caspase-8, but not caspase-10, are recruited to the receptor, and cells deficient in either FADD or caspase-8 blocked TRAIL-induced apoptosis. In addition, TRAIL initiates the activation of caspases, the loss of mitochondrial transmembrane potential (Deltapsi(m)), the cleavage of BID, and the redistribution of mitochondrial cytochrome c. Treatment of Jurkat cells with cyclosporin A delayed TRAIL-induced Deltapsi(m), caspase-3 activation and apoptosis. Similarly, Overexpression of Bcl-2 or Bcl-X(L) delayed, but did not inhibit, TRAIL-induced Deltapsi(m) and apoptosis. In contrast, XIAP, cowpox virus CrmA and baculovirus p35 inhibited TRAIL-induced apoptosis. These data suggest that death receptors (DR4 and DR5) and Fas receptors induced apoptosis through identical signaling pathway, and TRAIL-induced apoptosis via both mitochondrial-dependent and -independent pathways.
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PMID:Intracellular mechanisms of TRAIL: apoptosis through mitochondrial-dependent and -independent pathways. 1136 Jan 96


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