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

Photodynamic therapy (PDT) is a clinical approach that utilizes light-activated drugs for the treatment of a variety of pathologic conditions. The initiating events of PDT-induced apoptosis are poorly defined. It has been shown for other proapoptotic stimuli that the integral endoplasmic reticulum protein Bap31 is cleaved by caspases 1 and 8, but not by caspase-3. Further, a 20 kDa Bap31 cleavage fragment is generated which can induce apoptosis. In the current report, we sought to determine whether Bap31 cleavage and generation of p20 is an early event in PDT-induced apoptosis. The mitochondrial release of cytochrome c, involvement of caspases 1, 2, 3, 4, 6, 7, 8, and 10 and the status of several known caspase substrates, including Bap31, were evaluated in PDT-treated HeLa cells. Cytochrome c appeared in the cytosol immediately following light activation of the photosensitizer benzoporphyrin derivative monoacid ring A. Activation of caspases 3, 6, 7, and 8 was evident within 1-2 h post PDT. Processing of caspases 1, 2, 4, and 10 was not observed. Cleavage of Bap31 was observed at 2-3 h post PDT. The caspase-3 inhibitor DEVD-fmk blocked caspase-8 and Bap31 cleavage suggesting that caspase-8 and Bap31 processing occur downstream of caspase-3 activation in PDT-induced apoptosis. These results demonstrate that release of mitochondrial cytochrome c into the cytoplasm is a primary event following PDT, preceding caspase activation and cleavage of Bap31. To our knowledge, this is the first example of a chemotherapeutic agent inducing caspase-8 activation and demonstrates that caspase-8 activation can occur after cytochrome c release.
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PMID:Rapid cytochrome c release, activation of caspases 3, 6, 7 and 8 followed by Bap31 cleavage in HeLa cells treated with photodynamic therapy. 980 61

In this study we show that TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), also called Apo2L, activates the c-Jun N-terminal kinase (JNK). Interestingly, TRAIL-induced JNK activation occurs in a cell type-specific manner. In HeLa cells, TRAIL-induced JNK activation can be completely blocked with the cysteine protease inhibitor zVAD-fmk, whereas the same inhibitor has no, or even a stimulatory, effect on JNK activation in Kym-1 cells. Hence, TRAIL can engage at least two independent pathways leading to JNK activation, one that is cysteine protease-dependent and one that is cysteine protease-independent. To investigate whether the cysteine protease-dependent signaling of TRAIL leading to JNK activation is related to the apoptotic pathway engaged by this ligand, we investigated HeLa cells stably overexpressing a dominant negative mutant of FADD (Fas-associating protein with death domain) (GFP(green fluorescent protein)DeltaFADD). In these cells, TRAIL-induced cell death and activation of the apoptosis executioner caspase-8 (FLICE/MACH) and caspase-3 (YAMA, CPP-32, Apopain), that belong to caspase subfamily of cysteine proteases, were abrogated, whereas JNK activation remained unaffected and was still sensitive toward z-VAD-fmk. Similar data were found in HeLa cells overexpressing Apo1/Fas and GFPDeltaFADD upon stimulation with agonistic antibodies. These data suggest that cross-linking of the TRAIL receptors and Apo1/Fas, respectively, engages a FADD-dependent pathway leading to the activation of apoptotic caspases and, in parallel, a FADD-independent pathway leading to the stimulation of one or more cysteine proteases capable to activate JNK but not sufficient for the induction of cell death.
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PMID:TRAIL/Apo2L activates c-Jun NH2-terminal kinase (JNK) via caspase-dependent and caspase-independent pathways. 983 64

Sendai virus (SV) infection and replication lead to a strong cytopathic effect with subsequent death of host cells. We now show that SV infection triggers an apoptotic program in target cells. Incubation of infected cells with the peptide inhibitor z-VAD-fmk abrogated SV-induced apoptosis, indicating that proteases of the caspase family were involved. Moreover, proteolytic activation of two distinct caspases, CPP32/caspase-3 and, as shown for the first time in virus-infected cells, FLICE/caspase-8, could be detected. So far, activation of FLICE/caspase-8 has been described in apoptosis triggered by death receptors, including CD95 and tumor necrosis factor (TNF)-R1. In contrast, we could show that SV-induced apoptosis did not require TNF or CD95 ligand. We further found that apoptosis of infected cells did not influence the maturation and budding of SV progeny. In conclusion, SV-induced cell injury is mediated by CD95- and TNF-R1-independent activation of caspases, leading to the death of host cells without impairment of the viral life cycle.
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PMID:Sendai virus infection induces apoptosis through activation of caspase-8 (FLICE) and caspase-3 (CPP32). 984 76

Survivin is a member of the inhibitor of apoptosis protein (IAP) family. We investigated the antiapoptotic mechanism of Survivin, as well as its expression in 60 human tumor cell lines used for the National Cancer Institute's anticancer drug screening program. In cotransfection experiments, cell death induced by Bax or Fas (CD 95) was partially inhibited (mean +/- SD, 65% +/- 8%) by Survivin, whereas XIAP, another IAP family member, almost completely blocked cell death (93% +/- 4%) under the same conditions. Survivin and XIAP also protected 293 cells from apoptosis induced by overexpression of procaspase-3 and -7 and inhibited the processing of these zymogens into active caspases. In vitro binding experiments indicated that, like other IAP-family proteins, Survivin binds specifically to the terminal effector cell death proteases, caspase-3 and -7, but not to the proximal initiator protease caspase-8. Using a cell-free system in which cytosolic extracts were derived from control- or Survivin-transfected cells and where caspases were activated either by addition of cytochrome c and dATP or by adding recombinant active caspase-8, Survivin was able to substantially reduce caspase activity, as measured by cleavage of a tetrapeptide substrate, AspGluValAsp-aminofluorocoumarin. Similar results were obtained in intact cells when Survivin was overexpressed by gene transfection and caspase activation was induced by the anticancer drug etoposide. Survivin was expressed in all 60 cancer cell lines analyzed, with highest levels in breast and lung cancers and lowest levels in renal cancers. These findings indicate that Survivin, which is commonly expressed in human tumor cell lines, can bind the effector cell death proteases caspase-3 and -7 in vitro and inhibits caspase activity and cell death in cells exposed to diverse apoptotic stimuli. Although quantitative differences may exist, these observations suggest commonality in the mechanisms used by IAP-family proteins to suppress apoptosis.
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PMID:IAP-family protein survivin inhibits caspase activity and apoptosis induced by Fas (CD95), Bax, caspases, and anticancer drugs. 985 56

Different classes of anticancer drugs may trigger apoptosis by acting on different subcellular targets and by activating distinct signaling pathways. Here, we report that betulinic acid (BetA) is a prototype cytotoxic agent that triggers apoptosis by a direct effect on mitochondria. In isolated mitochondria, BetA directly induces loss of transmembrane potential independent of a benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone-inhibitable caspase. This is inhibited by bongkrekic acid, an agent that stabilizes the permeability transition pore complex. Mitochondria undergoing BetA-induced permeability transition mediate cleavage of caspase-8 (FLICE/MACH/Mch5) and caspase-3 (CPP32/Yama) in a cell-free system. Soluble factors such as cytochrome c or apoptosis-inducing factor released from BetA-treated mitochondria are sufficient for cleavage of caspases and nuclear fragmentation. Addition of cytochrome c to cytosolic extracts results in cleavage of caspase-3, but not of caspase-8. However, supernatants of mitochondria, which have undergone permeability transition, and partially purified apoptosis-inducing factor activate both caspase-8 and caspase-3 in cytosolic extracts and suffice to activate recombinant caspase-8. These findings show that induction of mitochondrial permeability transition alone is sufficient to trigger the full apoptosis program and that some cytotoxic drugs such as BetA may induce apoptosis via a direct effect on mitochondria.
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PMID:Activation of mitochondria and release of mitochondrial apoptogenic factors by betulinic acid. 985 46

We previously demonstrated that treatment with cycloheximide (CHX) converted the phenotype of Fas-resistant human prostatic carcinoma cell lines to Fas-sensitive and that resistance to Fas-mediated apoptosis was due to a dominant-negative protein(s). In this study, we investigated the sequential activation of caspase family members, to gain insight into the likely site of action of the suppressor protein(s). We did not find Tyr-Val-Ala-Aspase activity in any of the cell lines examined. Time-dependent Asp-Glu-Val-Aspase activity was detected during Fas-mediated apoptosis in Fas-sensitive cell lines PC3 and ALVA31. Asp-Glu-Val-Aspase activity in Fas-resistant cell lines DU145 and JCA1, was detected only under combined treatment with CHX and anti-Fas agonistic mAb. In experiments with caspase inhibitors we show that Fas-mediated apoptosis in PC3 is mainly executed by the caspase-3 subfamily, but another member(s) of the caspase family may be involved in Fas-mediated apoptosis in ALVA31, DU145, and JCA1. Western blot analysis revealed that Fas-ligation activated caspase-7, but not caspase-3. The activated form of caspase-8 was detected in DU145 only after 4 h of simultaneous treatment with CHX and anti-Fas mAb, whereas in PC3 caspase-8 was found to be activated after 1 h of Fas-ligation. We have also found that treatment with staurosporin did not activate caspase-8, whereas staurosporin induced apoptosis at the same levels in both Fas-resistant and Fas-sensitive cell lines. These results suggest that an inhibitory protein(s), which suppresses apoptosis in Fas-resistant cell lines, presumably acts at the apex of apoptotic cascade by preventing the activation of caspase-8.
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PMID:Fas-mediated apoptosis in human prostatic carcinoma cell lines occurs via activation of caspase-8 and caspase-7. 986 48

The activation of caspases appears to play a key role in programmed cell death. An increasing number of substrates have been identified that are cleaved by caspases. In a previous study, we have reported that human cPLA2 is proteolytically inactivated during apoptosis through cleavage by a caspase-3-like activity. Here, we show that in cotransfection experiments the previously identified cleavage site at Asp522 can be used by a wide variety of caspases belonging to different subfamilies. The formation of additional fragments implied differences in cleavage site usage between the closely related caspases-3 and -7. A different cleavage pattern of cPLA2 was observed with caspase-1. Mutational analysis identified the caspase-1 cleavage site at Asp459 within the sequence YQSD/N. Most interestingly, we found that even caspase-8, an upstream component of the proposed caspase cascade, cleaves cPLA2 in vitro. The presence of multiple cleavage sites warrants proteolysis and inactivation of the proinflammatory cPLA2 during apoptosis.
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PMID:Cleavage of human cytosolic phospholipase A2 by caspase-1 (ICE) and caspase-8 (FLICE). 987 25

Tumor necrosis factor-alpha (TNF-alpha) exerts two separate effects on neutrophils, stimulating effector functions while simultaneously inducing apoptosis. We examined here the involvement of caspases in neutrophil apoptosis and the effect of TNF-alpha-induced apoptosis on reactive oxygen production. Immunoblotting and affinity labeling showed activation of caspase-8, caspase-3, and a caspase with a large subunit of 18 kD (T18) in TNF-alpha-treated neutrophils. Active caspase-6 and -7 were not detectable in this cell type. Caspase-8 activated caspase-3 and T18 in neutrophil cytoplasmic extracts. zVAD-fmk blocked neutrophil apoptosis, in parallel with the inhibition of caspase activation. TNF-alpha-induced caspase activation was accompanied by a decrease in the ability of neutrophils to release superoxide anion. Conversely, TNF-alpha treatment in the presence of zVAD-fmk caused a prolonged augmentation of superoxide release. Granulocyte-macrophage colony-stimulating factor inhibited TNF-alpha-induced caspase activation and apoptosis, while reversing the diminution in superoxide release. These observations not only suggest that a caspase cascade mediates apoptotic events and downregulates oxygen radical production in TNF-alpha-treated neutrophils, but also raise the possibility that suppression of caspase activation with enhanced proinflammatory actions of TNF-alpha may underlie the pathogenesis of inflammatory diseases.
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PMID:Caspases mediate tumor necrosis factor-alpha-induced neutrophil apoptosis and downregulation of reactive oxygen production. 988 30

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

Stimulation of the CD95/Fas/Apo-1 receptor leads to apoptosis through activation of the caspase family of cysteine proteases and disruption of the mitochondrial transmembrane potential (Deltapsim). We show that, in Jurkat human T cells and peripheral blood lymphocytes, Fas-induced apoptosis is preceded by 1) an increase in reactive oxygen intermediates (ROI) and 2) an elevation of Deltapsim. These events are followed by externalization of phosphatidylserine (PS), disruption of Deltapsim, and cell death. The caspase inhibitor peptides, DEVD-CHO, Z-VAD.fmk, and Boc-Asp.fmk, blocked Fas-induced PS externalization, disruption of Deltapsim, and cell death, suggesting that these events are sequelae of caspase activation. By contrast, in the presence of caspase inhibitors, ROI levels and Deltapsim of Fas-stimulated cells remained elevated. Because ROI levels and Deltapsim are regulated by the supply of reducing equivalents from the pentose phosphate pathway (PPP), we studied the impact of transaldolase (TAL), a key enzyme of the PPP, on Fas signaling. Overexpression of TAL accelerated Fas-induced mitochondrial ROI production, Deltapsim elevation, activation of caspase-8 and caspase-3, proteolysis of poly(A)DP-ribose polymerase, and PS externalization. Additionally, suppression of TAL diminished these activities. Therefore, by controlling the balance between mitochondrial ROI production and metabolic supply of reducing equivalents through the PPP, TAL regulates susceptibility to Fas-induced apoptosis. Early increases in ROI levels and Deltapsim as well as the dominant effect of TAL expression on activation of caspase-8/Fas-associated death domain-like IL-1beta-converting enzyme, the most upstream member of the caspase cascade, suggest a pivotal role for redox signaling at the initiation of Fas-mediated apoptosis.
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PMID:Elevation of mitochondrial transmembrane potential and reactive oxygen intermediate levels are early events and occur independently from activation of caspases in Fas signaling. 997 3


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