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)

Apoptotic cell suicide initiated by ligation of CD95 (Fas/APO-1) occurs through recruitment, oligomerization and autocatalytic activation of the cysteine protease, caspase-8 (MACH, FLICE, Mch5). An endogenous mammalian regulator of this process, named Usurpin, has been identified (aliases for Usurpin include CASH, Casper, CLARP, FLAME-1, FLIP, I-FLICE and MRIT). This protein is ubiquitously expressed and exists as at least three isoforms arising by alternative mRNA splicing. The Usurpin gene is comprised of 13 exons and is clustered within approximately 200 Kb with the caspase-8 and -10 genes on human chromosome 2q33-34. The Usurpin polypeptide has features in common with pro-caspase-8 and -10, including tandem 'death effector domains' on the N-terminus of a large subunit/small subunit caspase-like domain, but it lacks key residues that are necessary for caspase proteolytic activity, including the His and Cys which form the catalytic substrates diad, and residues that stabilize the P1 aspartic acid in substrates. Retro-mutation of these residues to functional caspase counterparts failed to restore proteolytic activity, indicating that other determinants also ensure the absence of catalytic potential. Usurpin heterodimerized with pro-caspase-8 in vitro and precluded pro-caspase-8 recruitment by the FADD/MORT1 adapter protein. Cell death induced by CD95 (Fas/APO-1) ligation was attenuated in cells transfected with Usurpin. In vivo, a Usurpin deficit was found in cardiac infarcts where TUNEL-positive myocytes and active caspase-3 expression were prominent following ischemia/reperfusion injury. In contrast, abundant Usurpin expression (and a caspase-3 deficit) occurred in surrounding unaffected cardiac tissue, suggesting reciprocal regulation of these pro- and anti-apoptotic molecules in vivo. Usurpin thus appears to be an endogenous modulator of apoptosis sensitivity in mammalian cells, including the susceptibility of cardiac myocytes to apoptotic death following ischemia/ reperfusion injury.
...
PMID:Cell death attenuation by 'Usurpin', a mammalian DED-caspase homologue that precludes caspase-8 recruitment and activation by the CD-95 (Fas, APO-1) receptor complex. 1020 Apr 73

Mistletoe lectin I (ML-I) is a major active component in plant extracts of Viscum album that is increasingly used in adjuvant cancer therapy. ML-I exerts potent immunomodulating and cytotoxic effects, although its mechanism of action is largely unknown. We show that treatment of leukemic T- and B-cell lines with ML-I induced apoptosis, which required the prior activation of proteases of the caspase family. The involvement of caspases is demonstrated because (a) a peptide caspase inhibitor almost completely prevented ML-I-induced cell death and (b) proteolytic activation of caspase-8, caspase-9, and caspase-3 was observed. Because caspase-8 has been implicated as a regulator of apoptosis mediated by death receptors, we further investigated a potential receptor involvement in ML-I-induced effects. Cell death triggered by ML-I was neither attenuated in cell clones resistant to CD95 nor in cells that were rendered refractory to other death receptors by overexpressing a dominant-negative FADD mutant. In contrast, ML-I triggered a receptor-independent mitochondria-controlled apoptotic pathway because it rapidly induced the release of cytochrome c into the cytosol. Because ML-I was also observed to enhance the cytotoxic effect of chemotherapeutic drugs, these data may provide a molecular basis for clinical trials using MLs in anticancer therapy.
...
PMID:Mistletoe lectin activates caspase-8/FLICE independently of death receptor signaling and enhances anticancer drug-induced apoptosis. 1023 92

Interferon gamma (IFNgamma) induces apoptosis in purified human erythroid colony-forming cells (ECFC) and inhibits cell growth. Fas (APO-1; CD95) and Fas ligand (FasL) mediate apoptosis induced by IFNgamma, because Fas is significantly upregulated by IFNgamma, whereas Fas ligand is constitutively present in the ECFC and neutralization of FasL greatly reduces the apoptosis. Because conversion of caspases from their dormant proenzyme forms to active enzymes has a critical role in transducing a cascade leading to apoptosis, we performed further studies of the expression and activation of caspases in normal human and IFNgamma-treated day-6 ECFC to better understand the mechanism of IFNgamma action in producing this cell death. RNase protection assays showed that the caspase-1, -2, -6, -8, and -9 mRNAs were upregulated by IFNgamma, whereas the caspase-5 and -7 mRNAs were not increased. Western blots showed that FLICE/caspase-8 was upregulated and activated by 24 hours of incubation with IFNgamma. FADD was not similarly altered by incubation with IFNgamma. Western blots of ICE/caspase-1, which might be required for amplification of the initial FLICE activation signal, showed that pro-ICE expression significantly increased after treatment with IFNgamma for 24 hours and cleavage of pro-ICE also increased. CPP32/apopain/caspase-3, responsible for the proteolytic cleavage of poly (ADP) ribose polymerase (PARP), was also studied and treatment of ECFC with IFNgamma resulted in an increased concentration of caspase-3 by 24 hours and a clear induction of enzyme activation by 48 hours, which was identified by the appearance of its p17-kD peptide fragment. The cleavage of PARP was demonstrated by an obvious increase of the 89-kD PARP cleavage product, which was observed at almost the same time as caspase-3 activation in the IFNgamma-treated cells, whereas untreated ECFC showed little change. Peptide inhibitors of the caspase proteins, DEVD-fmk, DEVD-cho, YVAD-cho, and IETD-fmk, were incubated with the ECFC to obtain further evidence for the involvement of caspases in IFNgamma-induced apoptosis. The activation of FLICE/caspase-8 and CPP32/caspase-3 and cleavage of PARP clearly were inhibited, but the reduction of cell growth due to apoptosis, induced by IFNgamma, was only partially blocked by the presence of the inhibitors. These results indicate that IFNgamma acts on ECFC not only to upregulate Fas, but also to selectively upregulate caspases-1, -3, and -8, which are activated and produce apoptosis, whereas the concentrations of FasL and FADD are not demonstrably changed.
...
PMID:Interferon gamma induces upregulation and activation of caspases 1, 3, and 8 to produce apoptosis in human erythroid progenitor cells. 1023 83

Brief periods of in vitro hypoxia/ischemia induce apoptosis of cultured renal epithelial cells, but the underlying mechanisms remain unknown. We show that partial ATP depletion (approximately 10-65% of control) results in a duration-dependent induction of apoptosis in Madin-Darby canine kidney (MDCK) cells, as evidenced by internucleosomal DNA cleavage (DNA laddering and in situ nick end labeling), morphological changes (cell shrinkage), and plasma membrane alterations (externalization of phosphatidylserine). The ATP-depleted cells display a significant upregulation of Fas, Fas ligand, and the Fas-associating protein with death domain (FADD). Exogenous application of stimulatory Fas monoclonal antibodies also induces apoptosis in nonischemic MDCK cells, indicating that they retain Fas-dependent pathways of programmed cell death. Furthermore, cleavage of poly(ADP)ribose polymerase (PARP) is evident after ATP depletion, indicating activation of caspases. Indeed, the apoptotic cells display a significant increase in caspase-8 (FLICE) activity. Finally, apoptosis induced by ATP depletion is ameliorated by pretreatment with inhibitors of caspase-8 (IETD), caspase-1 (YVAD), or caspase-3 (DEVD) but is not affected by inhibitors of serine proteases (TPCK). Our results indicate that partial ATP depletion of MDCK cells results in apoptosis and that Fas- and caspase-mediated pathways may play a critical role.
...
PMID:Partial ATP depletion induces Fas- and caspase-mediated apoptosis in MDCK cells. 1036 72

Neutrophils undergo constitutive apoptosis when aged ex vivo. Recent studies have indicated roles for Fas/CD95 and the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase system in this process. We have investigated the role of protein kinase C (PKC) in neutrophil death. We show that there is proteolysis and activation of the novel isoform PKCdelta in aged neutrophils and that this process is accelerated by the addition of an agonistic Fas antibody. PKCdelta proteolysis occurs before the onset of any detectable features of apoptosis and pharmacologic inhibition of this enzyme inhibits neutrophil apoptosis. PKCdelta cleavage and activation is dependent on caspase-8/FADD-like interleukin-1beta converting enzyme (FLICE)-mediated processing of caspase-3/CPP32. Neutrophil survival is prolonged by the addition of broad spectrum (BD.fmk) or caspase-8 targeted (zIETD.fmk) peptide caspase inhibitors. Inhibition of PKCdelta does not prevent apoptosis triggered by factor withdrawal in immature hematopoietic cells, including normal human CD34(+) progenitors indicating that within a given lineage, the mechanisms of apoptosis may be differentiation-stage-specific. Ex vivo aging of neutrophils leads to the increasing production of reactive oxygen species and this is attenuated in cells treated with either caspase or PKCdelta inhibitors. Proteolytically activated PKCdelta acts as a molecular link between the Fas/CD95 receptor and the NADPH-oxidase system and plays a central role in regulating the process of neutrophil apoptosis.
...
PMID:Caspase-mediated proteolysis and activation of protein kinase Cdelta plays a central role in neutrophil apoptosis. 1038 25

We have assessed in detail the effect of cisplatin-activated programmed cell death in the cisplatin-sensitive human ovarian cancer cell line A2780 and two drug-resistant subclones, CP70 and C30. To determine whether the differential extent of apoptosis observed between the sensitive and resistant ovarian cancer cell lines was the result of dissimilar upstream signaling events, we assessed the execution of apoptotic events that precede target protein proteolysis and subsequent chromosomal DNA degradation. Proteolytic degradation of procaspase-3 was observed in both the CP70 and C30 cells following IC50 cisplatin treatment, whereas no proteolyzed caspase-3 subunits were detected in the A2780 cells. However, using a direct enzymatic assay measuring cleavage of the synthetic peptide substrate (N-acetyl-Asp-Glu-Val-Asp-p-nitroanilide), activity was detected in extracts prepared from A2780 cells treated at the IC90 level of cisplatin and was 2-3-fold less than that of extracts prepared from CP70 and C30 cells. Because the activation of procaspase-3 by caspase-9 requires the release of cytochrome c into the cytoplasm, we determined the level of cytoplasmic cytochrome c in each cell line in response to cisplatin treatment. Consistent with the caspase-3 activation data, a very small increase in cytoplasmic cytochrome c was observed in A2780 cells following cisplatin treatment, whereas dramatic increases were evident in both the CP70 and C30 cell lines. The expression of the mitochondrial factors Bcl-2, Bcl-x, and Bax was determined because each has been implicated in the regulation or release of cytochrome c at the level of the mitochondria. Bcl-2 and Bcl-xL proteins remained relatively unchanged in expression for over 48 h after exposure to cisplatin in the A2780 cell lines. However, within the same time period, expression of Bcl-2 decreased in the CP70- and C30-resistant cell lines, whereas an increase in Bcl-xL expression was observed. Expression of the proapoptotic Bcl-xS protein was observed in only the resistant CP70 and C30 cell lines independent of cisplatin treatment. A change in the expression of Mr 24,000 Bax to a Mr 21,000 isoform was evidenced in the A2780 cells within 48 h of cisplatin treatment and, to a greater extent, in the CP70 and C30 cells, which also expressed a Mr 16,000 Bax variant. Evidence for an alternative apoptotic pathway in A2780 cells was obtained by demonstrating increased FADD expression in response to cisplatin treatment. These results support a model in which cisplatin-induced programmed cell death in the cisplatin-sensitive A2780 and -resistant CP70 and C30 cells proceeds via caspase-3-independent and -dependent pathways, respectively.
...
PMID:Cisplatin-induced apoptosis proceeds by caspase-3-dependent and -independent pathways in cisplatin-resistant and -sensitive human ovarian cancer cell lines. 1039 48

Apoptosis is an evolutionarily conserved process that is critical for tissue homeostasis and development including sex determination in essentially all multicellular organisms. Here, we report the cloning of an ankyrin repeat-containing protein, termed F1Aalpha, in a yeast two-hybrid screen using the cytoplasmic domain of Fas (CD95/APO-1) as bait. Amino acid sequence analysis indicates that F1Aalpha has extensive homology to the sex-determining protein FEM-1 of the Caenorhabditis elegans, which is required for the development of all aspects of the male phenotype. F1Aalpha associates with the cytoplasmic domains of Fas and tumor necrosis factor receptor 1, two prototype members of the "death receptor" family. The F1Aalpha protein also oligomerizes. Overexpression of F1Aalpha induces apoptosis in mammalian cells, and co-expression of Bcl-XL or the dominant negative mutants of either FADD or caspase-9 blocks this effect. Deletion analysis revealed the center region of F1Aalpha, including a cluster of five ankyrin repeats to be necessary and sufficient for maximum apoptotic activity, and the N-terminal region appears to regulate negatively this activity. Furthermore, F1Aalpha is cleaved by a caspase-3-like protease at Asp(342), and the cleavage-resistant mutant is unable to induce apoptosis upon overexpression. F1Aalpha is therefore a member of a growing family of death receptor-associated proteins that mediates apoptosis.
...
PMID:F1Aalpha, a death receptor-binding protein homologous to the Caenorhabditis elegans sex-determining protein, FEM-1, is a caspase substrate that mediates apoptosis. 1054 91

Activation-induced cell death (AICD) in T cells is mediated by CD95 ligand (CD95L)/receptor interaction, which has also been implicated in apoptosis induction by some anticancer agents. In this article we show that both anti-CD3-triggering (AICD) and doxorubicin treatment led to the production of a functionally active CD95L in the CD3+/T-cell receptor-positive (TCR+) T leukemia cell line H9. CD95L-expressing H9 cells killed CD95-sensitive J16 or CEM target cells, but not CD95-resistant CEM or J16 cells overexpressing dominant negative FADD (J16/FADD-DN). By immunoprecipitation, CD95L was physically bound to CD95, suggesting that AICD and doxorubicin-induced apoptosis involve CD95L-mediated CD95 aggregation, thereby triggering the CD95 death pathway. CD95 aggregation was associated with the recruitment of FADD and caspase-8 to the CD95 receptor to form the CD95 death-inducing signaling complex (DISC), resulting in caspase-8 activation and cleavage of the effector caspase-3 and PARP. Blocking of the CD95L/receptor interaction by antagonistic antibodies to CD95 or to CD95L also blocked AICD and inhibited the early phase of doxorubicin-induced apoptosis, though cell death induced by doxorubicin eventually proceeded in a CD95-independent manner. These findings may explain some conflicting data on the role of death receptor systems in drug-induced apoptosis. Thus, in cells with an inducible CD95 receptor/ligand system, drug-induced apoptosis may be mediated by CD95L-initiated DISC formation and activation of downstream effector programs similar to AICD in T cells. (Blood. 2000;95:301-308)
...
PMID:Functional CD95 ligand and CD95 death-inducing signaling complex in activation-induced cell death and doxorubicin-induced apoptosis in leukemic T cells. 1060 16

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.
...
PMID:FADD is required for multiple signaling events downstream of the receptor Fas. 1061 4

The tyrphostin AG957 (NSC 654705) inhibits p210bcr/abl, the transforming kinase responsible for most cases of chronic myelogenous leukemia (CML). The present studies were performed to determine the fate of AG957-treated cells and assess the selectivity of AG957 for CML myeloid progenitors. When K562 cells (derived from a patient with blast crisis CML) were treated with AG957, dose- and time-dependent p210bc/abl down-regulation was followed by mitochondrial release of cytochrome c, activation of caspase-9 and caspase-3, and apoptotic morphological changes. These apoptotic changes were inhibited by transfection with cDNA encoding dominant negative caspase-9 but not dominant-negative FADD or blocking anti-Fas antibodies. In additional experiments, a 24-h AG957 exposure caused dose-dependent inhibition of K562 colony formation in soft agar. To extend these studies to clinical samples of CML, peripheral blood mononuclear cells from 10 chronic phase CML patients and normal controls were assayed for the growth of hematopoietic colonies in vitro in the presence of increasing concentrations of AG957. These assays demonstrated selectivity of AG957 for CML progenitors, with median IC50s (CML versus normal) of 7.3 versus >20 microM AG957 in granulocyte colony-forming cells (P < 0.001), 5.3 versus >20 microM in granulocyte/macrophage colony-forming cells (P < 0.05), and 15.5 versus > 20 microM in erythroid colony-forming cells (P > 0.05). The adamantyl ester of AG957 (NSC 680410) down-regulated p210bcr/abl in K562 cells and inhibited granulocyte colony formation in CML specimens at lower concentrations without enhanced toxicity in normal progenitors. These observations not only demonstrate that AG957-induced p210bcr/abl down-regulation is followed by activation of the cytochrome c/Apaf-1/caspase-9 pathway but also indicate that this class of kinase inhibitor exhibits selectivity worthy of further evaluation.
...
PMID:Effects of the bcr/abl kinase inhibitors AG957 and NSC 680410 on chronic myelogenous leukemia cells in vitro. 1065 55


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

---