Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.22.56 (caspase-3)
35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Programmed cell death, or apoptosis, is inhibited by the antiapoptotic oncogene, Bcl-2, and is mediated by a cascade of aspartate-specific cysteine proteases, or caspases, related to interleukin 1-beta converting enzyme. Depending on cell type, apoptosis can be induced by treatment with thapsigargin (TG); a selective inhibitor of the endoplasmic reticulum-associated calcium-ATPase. The role of caspases in mediating TG-induced apoptosis was investigated in the Bcl-2-negative human breast cancer cell line, MDA-MB-468. Apoptosis developed in MDA-MB-468 cells over a period of 24-72 h following treatment with 100 nM TG, and was prevented by Bcl-2 overexpression. TG-induced apoptosis was associated with activation of caspase-3 and was inhibited by stable expression of the baculovirus p35 protein, an inhibitor of caspase activity. Also, TG-induced apoptosis was inhibited by treating cells with Z-VAD-fmk, a cell-permeable fluoromethylketone inhibitor of caspases. These findings indicate that TG-induced apoptosis of MDA-MB-468 breast cancer cells is subject to inhibition by Bcl-2 and is mediated by caspase activity. This model system should be useful for further investigation directed toward understanding the role of calcium in signaling apoptosis, and its relationship to Bcl-2 and the caspase proteolytic cascade.
...
PMID:Baculovirus p35 and Z-VAD-fmk inhibit thapsigargin-induced apoptosis of breast cancer cells. 929 14

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.
...
PMID:p28 Bap31, a Bcl-2/Bcl-XL- and procaspase-8-associated protein in the endoplasmic reticulum. 933 38

Caspases plays a key role in the execution phase of apoptosis. "Initiator" caspases, such as caspase-8, activate "effector" caspases, such as caspase-3 and -7, which subsequently cleave cellular substrates thereby precipitating the dramatic morphological changes of apoptosis. Following treatment of mice with an agonistic anti-Fas antibody to induce massive hepatocyte apoptosis, we now demonstrate a distinct subcellular localization of the effector caspases-3 and -7. Active caspase-3 is confined primarily to the cytosol, whereas active caspase-7 is associated almost exclusively with the mitochondrial and microsomal fractions. These data suggest that caspases-3 and -7 exert their primary functions in different cellular compartments and offer a possible explanation of the presence of caspase homologs with overlapping substrate specificities. Translocation and activation of caspase-7 to the endoplasmic reticulum correlates with the proteolytic cleavage of the endoplasmic reticular-specific substrate, sterol regulatory element-binding protein 1. Liver damage, induction of apoptosis, activation and translocation of caspase-7, and proteolysis of sterol regulatory element-binding protein 1 are all blocked by the caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone (Z-VAD. fmk). Our data demonstrate for the first time the differential subcellular compartmentalization of specific effector caspases following the induction of apoptosis in vivo.
...
PMID:Different subcellular distribution of caspase-3 and caspase-7 following Fas-induced apoptosis in mouse liver. 955 51

We examined the effects of the cell-permeable, broad spectrum peptide caspase inhibitors, benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethyl ketone (Z-VAD.fmk), and BOC-Asp(OMe)-fluoromethyl ketone (BOC-D.fmk), on apoptosis induced by anti-CD2, anti-Fas, and the protein kinase inhibitor staurosporine in activated human peripheral T lymphocytes. We monitored ultrastructural, flow cytometric, and biochemical apoptotic changes, including externalization of phosphatidylserine, cleavage of poly(ADP-ribose) polymerase (PARP) and lamins, activation of caspase-3 and caspase-7, decrease in mitochondrial membrane potential, and DNA fragmentation. Z-VAD.fmk and BOC-D.fmk completely inhibited all the biochemical and ultrastructural changes of apoptosis in anti-Fas-treated cells. In marked contrast, neither Z-VAD.fmk nor BOC-D.fmk inhibited CD2- or staurosporine-mediated cell shrinkage, dilatation of the endoplasmic reticulum (seen in anti-CD2-treated cells), externalization of phosphatidylserine, and loss of mitochondrial membrane potential that accompanied cell death. However, these inhibitors did inhibit the cleavage of PARP and lamins and the formation of hypodiploid cells, and partially inhibited chromatin condensation. These results demonstrate that in activated T cells, anti-CD2 and staurosporine induce a caspase-independent cell death pathway that exhibits prominent cytoplasmic features of apoptosis. However, caspase activation is required for the proteolytic degradation of nuclear substrates such as PARP and lamins together with the DNA fragmentation and extreme chromatin condensation that occur in apoptotic cells.
...
PMID:Caspase-independent cell death induced by anti-CD2 or staurosporine in activated human peripheral T lymphocytes. 975 54

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.
...
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

We have shown previously [E. Sikora, A. Bielak-Zmijewska, K. Piwocka, J. Skierski, and E. Radziszewska (1997) Biochem. Pharmacol. 54, 899-907] that curcumin prevents formation of oligonucleosomal DNA fragmentation in rat thymocytes and human leukemic T lymphocytes (Jurkat cells) induced to undergo apoptosis. In this paper we show that 50 microM curcumin by itself induces cell death in Jurkat cells, but its symptoms differ from those observed after a short ultraviolet (uv) irradiation. Ultraviolet-irradiated Jurkat cells displayed typical symptoms of apoptosis: morphological changes, internucleosomal and high-molecular-weight DNA fragmentation, formation of sub-G1 fractions in DNA content frequency histograms, and dissipation of the mitochondrial transmembrane electric potential (Delta psi). In contrast, curcumin-treated Jurkat cells exhibited DNA splitting into high-, but not low-, molecular-weight fragments. These cells retained their high mitochondrial Delta psi, and the content of Ca2+ in endoplasmic reticulum stores remained at the level typical for untreated cells. The frequency of opening of the mitochondrial permeability transition pores in curcumin-treated cells was decreased compared to the controls, whereas uv irradiation made these pores completely open. Curcumin did not produce any change in the activity of caspase-3, whereas uv irradiation considerably activated this protease. The morphology of curcumin-treated cells displayed chromatin condensation, which was insensitive to the caspase inhibitor z-VAD-fmk, but no formation of typical apoptotic bodies, as was the case after uv irradiation. In contrast to uv-irradiated cells, curcumin-treated Jurkat cells considerably increased the level of Bcl-2. It is concluded that the programmed cell death induced by curcumin in Jurkat cells differs from "classical" by the lack of mitochondrial depolarization and of the involvement of caspases.
...
PMID:A novel apoptosis-like pathway, independent of mitochondria and caspases, induced by curcumin in human lymphoblastoid T (Jurkat) cells. 1036 29

The proteins Bcl-2 and Bcl-X(L) prevent apoptosis, but their mechanism of action is unclear. We examined the role of Bcl-2 and Bcl-X(L) in the regulation of cytosolic Ca(2+), nitric oxide production (NO), c-Jun NH(2)-terminal kinase (JNK) activation, and apoptosis in Jurkat T cells. Thapsigargin (TG), an inhibitor of the endoplasmic reticulum-associated Ca(2+) ATPase, was used to disrupt Ca(2+) homeostasis. TG acutely elevated intracellular free Ca(2+) and mitochondrial Ca(2+) levels and induced NO production and apoptosis in Jurkat cells transfected with vector (JT/Neo). Buffering of this Ca(2+) response with 1, 2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester (BAPTA-AM) or inhibiting NO synthase activity with N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME) blocked TG-induced NO production and apoptosis in JT/Neo cells. By contrast, while TG produced comparable early changes in the Ca(2+) level (i.e., within 3 h) in Jurkat cells overexpressing Bcl-2 and Bcl-X(L) (JT/Bcl-2 or JT/Bcl-X(L)), NO production, late (36-h) Ca(2+) accumulation, and apoptosis were dramatically reduced compared to those in JT/Neo cells. Exposure of JT/Bcl-2 and JT/Bcl-X(L) cells to the NO donor, S-nitroso-N-acetylpenacillamine (SNAP) resulted in apoptosis comparable to that seen in JT/Neo cells. TG also activated the JNK pathway, which was blocked by L-NAME. Transient expression of a dominant negative mutant SEK1 (Lys-->Arg), an upstream kinase of JNK, prevented both TG-induced JNK activation and apoptosis. A dominant negative c-Jun mutant also reduced TG-induced apoptosis. Overexpression of Bcl-2 or Bcl-X(L) inhibited TG-induced loss in mitochondrial membrane potential, release of cytochrome c, and activation of caspase-3 and JNK. Inhibition of caspase-3 activation blocked TG-induced JNK activation, suggesting that JNK activation occurred downstream of caspase-3. Thus, TG-induced Ca(2+) release leads to NO generation followed by mitochondrial changes including cytochrome c release and caspase-3 activation. Caspase-3 activation leads to activation of the JNK pathway and apoptosis. In summary, Ca(2+)-dependent activation of NO production mediates apoptosis after TG exposure in JT/Neo cells. JT/Bcl-2 and JT/Bcl-X(L) cells are susceptible to NO-mediated apoptosis, but Bcl-2 and Bcl-X(L) protect the cells against TG-induced apoptosis by negatively regulating Ca(2+)-sensitive NO synthase activity or expression.
...
PMID:Bcl-2 and Bcl-X(L) block thapsigargin-induced nitric oxide generation, c-Jun NH(2)-terminal kinase activity, and apoptosis. 1040 55

GRP94 is a 94-kDa chaperone glycoprotein with Ca(2+)-binding properties. We report here that during apoptosis induced by the topoisomerase II inhibitor etoposide, a fraction of GRP94 associated with the endoplasmic reticulum membrane undergoes specific proteolytic cleavage, coinciding with the activation of the caspase CPP32 and initiation of DNA fragmentation. In vivo, inhibitors of caspases able to block etoposide-induced apoptosis can only partially protect GRP94 from proteolytic cleavage, whereas complete inhibition is observed with calpain inhibitor I but not with the proteasome inhibitor. In vitro, GRP94 is not a substrate for CPP32; rather, it can be completely cleaved by calpain, a Ca(2+)-regulated protease. The cleavage of GRP94 by calpain is Ca(2+)-dependent and generates a discrete polypeptide of 80 kDa. In contrast, calpain has no effect on other stress proteins such as GRP78 or HSP70. Further, immunohistochemical staining reveals specific co-localization of GRP94 with calpain in the perinuclear region following etoposide treatment. We further showed that reduction of GRP94 by antisense decreased cell viability in etoposide-treated Jurkat cells. Our studies provide new evidence that the cytoprotective GRP94, as in the case of the antiapoptotic protein Bcl-2, can be targets of proteolytic cleavage themselves during the apoptotic process.
...
PMID:The endoplasmic reticulum chaperone glycoprotein GRP94 with Ca(2+)-binding and antiapoptotic properties is a novel proteolytic target of calpain during etoposide-induced apoptosis. 1049 10

Environmental stress induces the synthesis of glucose-regulated proteins (Grps) in the endoplasmic reticulum (ER) and heat shock proteins (Hsps) in the cytoplasm. Iodoacetamide (IDAM), a prototypical alkyating agent, induces both Grp and Hsp synthesis in renal epithelial cells and causes necrosis which is prevented by prior activation of the ER stress response (pre-ER stress) [Liu, H., et al. (1997) J. Biol. Chem. 272, 21751-21759]. In this study, we examined the biochemical pathways leading to IDAM-induced apoptosis and investigated the role of the ER stress response in apoptotic cell death. The antioxidant N,N'-diphenyl-p-phenylenediamine (DPPD) prevented necrosis after IDAM treatment, but the cells went on to die with hallmarks of apoptosis, i.e., cell detachment, caspase-3 activation, cleavage of poly(ADP-ribose)polymerase (PARP), and DNA-ladder formation, all of which were blocked by the general caspase inhibitor zVAD. As with IDAM-induced necrosis, dithiothreitol protected against apoptosis, but cell permeable calcium chelators did not, suggesting that distinct biochemical pathways mediate these two forms of cell death. Pre-ER stress, but not heat shock, prevented IDAM-induced apoptosis. pkASgrp78 cells are deficient in Grp78 induction due to expression of a grp78 antisense RNA and are more sensitive to necrosis. However, these cells were resistant to IDAM-induced apoptosis and had increased basal levels of Grp94 and a KDEL-containing protein of about 50 kDa. Thus, the expression of grp78 antisense perturbs ER functions and activates expression of other ER stress genes accounting for the resistance to apoptosis. Taken together, the data describe functionally distinct signaling pathways through which the ER regulates apoptosis and necrosis caused by chemical toxicants.
...
PMID:Distinct endoplasmic reticulum signaling pathways regulate apoptotic and necrotic cell death following iodoacetamide treatment. 1052 70

Earlier reports have shown that herpes simplex virus 1 (HSV-1) mutants induce programmed cell death and that wild-type virus blocks the execution of the cell death program triggered by expression of viral genes, by the Fas and tumor necrosis factor pathways, or by nonspecific stress agents. In particular, an earlier report from this laboratory showed that the mutant virus d120 lacking the genes encoding infected cell protein 4 (ICP4), the major regulatory protein of the virus, induces a caspase-3-independent pathway of apoptosis in human SK-N-SH cells. Here we report that the pathway of apoptosis induced by the d120 mutant in human HEp-2 cells is caspase dependent. Specifically, in HEp-2 cells infected with d120, (i) a broad-range inhibitor of caspase activity, z-vad-FMK, efficiently blocked DNA fragmentation, (ii) cytochrome c was released into the cytoplasm, (iii) caspase-3 was activated inasmuch as poly(ADP-ribose) polymerase was cleaved, and (iv) chromatin condensation and fragmentation of cellular DNA were observed. In parallel studies, HEp-2 cells were transfected with a plasmid encoding human Bcl-2 and a clone (VAX-3) expressing high levels of Bcl-2 was selected. This report shows that Bcl-2 blocked all of the manifestations associated with programmed cell death caused by infection with the d120 mutant. Consistent with their resistance to programmed cell death, VAX-3 cells overproduced infected cell protein 0 (ICP0). An unexpected observation was that ICP0 encoded by the d120 mutant accumulated late in infection in small, quasi-uniform vesicle-like structures in all cell lines tested. Immunofluorescence-based colocalization studies indicated that these structures were not mitochondria or components of the endoplasmic reticulum or the late endosomal compartment. These studies affirm the conclusion that HSV can induce programmed cell death at multiple steps in the course of its replication, that the d120 mutant can induce both caspase-dependent and -independent pathways of programmed cell death, and that virus-induced stimuli of programmed cell death may differ with respect to the pathway that they activate.
...
PMID:Bcl-2 blocks a caspase-dependent pathway of apoptosis activated by herpes simplex virus 1 infection in HEp-2 cells. 1064 66


1 2 3 4 5 6 7 8 9 10 Next >>

---