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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Murine L929 fibrosarcoma cells were transfected with the human Fas (APO-1/CD95) receptor, and the role of various caspases in Fas-mediated cell death was assessed. Proteolytic activation of procaspase-3 and -7 was shown by Western analysis. Acetyl-Tyr-Val-Ala-Asp-chloromethylketone and benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethylketone++ +, tetrapeptide inhibitors of caspase-1- and caspase-3-like proteases, respectively, failed to block Fas-induced apoptosis. Unexpectedly, the broad-spectrum caspase inhibitors benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone and benzyloxycarbonyl-Asp(OMe)-fluoromethylketone rendered the cells even more sensitive to Fas-mediated cell death, as measured after 18 h incubation. However, when the process was followed microscopically, it became clear that anti-Fas-induced apoptosis of Fas-transfected L929 cells was blocked during the first 3 h, and subsequently the cells died by necrosis. As in tumor necrosis factor (TNF)-induced necrosis, Fas treatment led to accumulation of reactive oxygen radicals, and Fas-mediated necrosis was inhibited by the oxygen radical scavenger butylated hydroxyanisole. However, in contrast to TNF, anti-Fas did not activate the nuclear factor kappaB under these necrotic conditions. These results demonstrate the existence of two different pathways originating from the Fas receptor, one rapidly leading to apoptosis, and, if this apoptotic pathway is blocked by caspase inhibitors, a second directing the cells to necrosis and involving oxygen radical production.
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PMID:Dual signaling of the Fas receptor: initiation of both apoptotic and necrotic cell death pathways. 973 Aug 93

Therapeutic preparations of normal human IgG for i.v. use (i.v.Ig) exhibit a broad spectrum of immunoregulatory activities in vitro and in vivo. I.v.Ig has been shown to inhibit the proliferation of activated B and T lymphocytes and of several autonomously growing cell lines. In this study, we demonstrate that i.v.Ig induces apoptosis in leukemic cells of lymphocyte and monocyte lineage and in CD40-activated normal tonsillar B cells, involving, at least in part, Fas (CD95/APO-1) and activation of caspases. I.v.Ig-induced apoptosis was higher in Fas-sensitive HuT78 cells than in Fas-resistant HuT78.B1 mutant cells, and soluble Fas inhibited IVIg-induced apoptosis. I.v.Ig immunoprecipitated Fas from Fas-expressing transfectants and recognized purified Fas/glutathione-S-transferase fusion proteins upon immunoblotting. Affinity-purified anti-Fas Abs from i.v.Ig induced apoptosis of CEM T cells at a 120-fold lower concentration than unfractionated i.v.Ig. Inhibitors of cysteine proteases of the caspase family, caspase 1 (IL-1beta-converting enzyme) and caspase 3 (Yama/CPP32b), partially inhibited i.v.Ig-induced apoptosis of CEM cells. Furthermore, cleavage of poly(A)DP-ribose polymerase into an 85-kDa signature death fragment was observed in CEM cells following i.v.Ig treatment. Thus, normal IgG induces apoptosis in lymphocytes and monocytes. Our results provide evidence for a role of Fas, bring new insights into the mechanisms of action of i.v.Ig in autoimmune diseases, and suggest a role of normal Ig in controlling cell death and proliferation.
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PMID:Therapeutic preparations of normal polyspecific IgG (IVIg) induce apoptosis in human lymphocytes and monocytes: a novel mechanism of action of IVIg involving the Fas apoptotic pathway. 975 5

Apoptosis mediated by anticancer drugs may involve activation of death-inducing ligand/receptor systems such as CD95 (APO-1/Fas), cleavage of caspases, and perturbance of mitochondrial functions. We investigated the sequence of these events in SHEP neuroblastoma cells transfected with Bcl-2 or Bcl-X(L) using two different drugs, namely, doxorubicin (Doxo), which activates the CD95/CD95 ligand (CD95-L) system, and betulinic acid (Bet A), which does not enhance the expression of CD95 or CD95-L and which, as shown here, directly targets mitochondria. Apoptosis induced by both drugs was inhibited by Bcl-2 or Bcl-X(L) overexpression or by bongkrekic acid, an agent that stabilizes mitochondrial membrane barrier function, suggesting a critical role for mitochondria. After Doxo treatment, enhanced CD95/CD95-L expression and caspase-8 activation were not blocked by Bcl-2 or Bcl-X(L) and were found in cells with a mitochondrial transmembrane potential (delta psi(m)) that was still normal (delta psi(m)high cells). In marked contrast, after Bet A treatment, caspase-8 activation occurred in a Bcl-2- or Bcl-X(L)-inhibitable fashion and was confined to cells that had lost their delta psi(m) (delta psi(m)low cells). Mitochondria from cells treated with either Doxo or Bet A induced cleavage of both caspase-8 and caspase-3 in cytosolic extracts. Thus, caspase-8 activation may occur upstream or downstream of mitochondria, depending on the apoptosis-initiating stimulus. In contrast to caspase-8, cleavage of caspase-3 or poly(ADP-ribose)polymerase was always restricted to delta psi(m)low cells, downstream of the Bcl-2- or Bcl-X(L)-controlled checkpoint of apoptosis. Cytochrome c, released from mitochondria undergoing permeability transition, activated caspase-3 but not caspase-8 in a cell-free system. However, both caspases were activated by apoptosis-inducing factor, indicating that the mechanism of caspase-8 activation differed from that of caspase-3 activation. Taken together, our findings demonstrate that perturbance of mitochondrial function constitutes a central coordinating event in drug-induced cell death.
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PMID:Molecular ordering of apoptosis induced by anticancer drugs in neuroblastoma cells. 976 78

Fas (APO-1/CD95) is a cell-surface protein that can mediate apoptosis upon specific ligand or antibody binding. The Bcl-2 protein may function as a modulator of Fas-induced apoptosis by blocking a downstream activation step, and Bcl-2 expression in acute lymphoblastic leukemia (ALL) cells appears to depend partly on expression of a wild-type (wt) p53 tumor suppressor gene (Findley et al, Blood 1997; 89: 2986). We therefore investigated the relationship between sensitivity to Fas-mediated apoptosis and (1) Fas expression, (2) p53 status, and (3) Bcl-2 protein levels in pediatric ALL cell lines and primary leukemic cells. Cell lines included 21 B cell precursor (BCP)-ALL and four T-ALL lines; in five cases, cryopreserved primary leukemic cells from which these lines were established were also examined. Additionally, we evaluated the effect of anti-Fas monoclonal antibody on the activation of protease CPP32 and induction of apoptosis in these lines. By SSCP analysis and DNA sequencing, we detected p53 mutations (mt) in eight out of 25 ALL cell lines (exon-7, codon 248 n=6; exon-8, codon 273, n=2). The expression of Fas and Bcl-2 was examined by immunofluorescence staining and quantified as the number of molecules of equivalent soluble fluorochrome (MESF). Elevated levels of Fas were expressed in all six lines with a mutation of p53 in codon 248 (1500 to 10800 MESF). Although Fas was detectable in seven of the 17 lines with wt-p53, expression was lower (150-900 MESF) compared with mt-p53+ lines. Bcl-2 was expressed in 10 of the 25 lines. Most (9/10) wt-p53+ lines expressed Bcl-2, whereas only one of eight mt-p53+ lines and no p53-null lines expressed this protein. Treatment of Fas-positive lines with anti-Fas monoclonal antibody (200 ng/ml) for 6 h induced activation of CPP32 and apoptosis in eight of 13 Fas+ lines. Sensitivity to Fas-mediated apoptosis was associated with a mt-p53 phenotype and absence of Bcl-2 expression. Six of eight Fas+/Fas-sensitive (S) lines were mt-53+/Bcl-2-, whereas only two Fas+/Fas-S lines were wt-p53+/Bcl-2+; both of these latter lines expressed low levels of Bcl-2 compared to Fas-resistant lines. In contrast, four of five Fas+/Fas-resistant (R) lines were wt-p53+/Bcl-2+; the exception was p53-null/Bcl-2- but expressed a low level of Fas (150 MESF). Activation of the cysteine protease CPP32 and cleavage of its substrate poly(ADP-ribose)polymerase (PARP) was also detected in Fas-S but not Fas-R lines. We obtained similar results from both the primary leukemic cells and the corresponding cell lines in five cases: overexpression of Fas and Fas-sensitivity were present in mt-p53+/Bcl-2- but not wt-p53+/Bcl-2+ cells. These results suggest that some pediatric ALL cells expressing mt-p53+ may be sensitive to Fas-mediated apoptosis due to high levels of Fas expression and lack of Bcl-2, and further suggest that molecular methods of activating Fas may be useful for therapy of refractory ALL with the Fas+/mt-p53+ phenotype.
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PMID:Sensitivity to Fas-mediated apoptosis in pediatric acute lymphoblastic leukemia is associated with a mutant p53 phenotype and absence of Bcl-2 expression. 982 51

It is now well established that the caspases, a family of cysteine proteases, play a key role in apoptosis. Although overexpressing each of the caspases in cells triggered apoptosis, the precise role and contribution of individual caspases are still unclear. Caspase-1, the first caspase discovered, was initially implicated in mammalian apoptosis because of its similarity to the gene product ced-3. Using whole cells as well as an in vitro system to study apoptosis, the role of caspase-1 in Fas-mediated apoptosis in Jurkat T cells was examined in greater detail. Using various peptide-based caspase inhibitors, our results showed that N-acetyl-Tyr-Val-Ala-Asp chloromethyl ketone and benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethyl ketone efficiently blocked Fas-mediated apoptosis in Jurkat T cells, whereas N-acetyl-Tyr-Val-Ala-Asp aldehyde, which is more specific for caspase-1, had little effect. Cell lysates derived from anti-Fas-stimulated cells, which readily induced apoptotic nuclei morphology and DNA fragmentation in isolated thymocyte nuclei, had no caspase-1 activity using proIL-1beta as a substrate. Time-course studies showed no caspase-1 activity during the activation of apoptosis in Jurkat cells by agonistic Fas antibodies. Furthermore, no pro-caspase-1 protein nor activated form of the protein was detected in normal or apoptotic Jurkat cells. In contrast, both caspase-2 and caspase-3 were readily detected as proenzymes in control cells and their activated forms were detected in apoptotic cells. Incubation of recombinant active caspase-1 with control cell lysates did not activate the apoptotic cascade as shown by the lack of detectable apoptotic nuclei promoting activity using isolated nuclei as substrate. However, under similar conditions proIL-1beta was readily processed into the mature cytokine, indicating that the recombinant caspase-1 remained active in the presence of control cell lysates. Taken together our results demonstrate that caspase-1 is not required for the induction of apoptosis in Jurkat T cells mediated by the Fas antigen.
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PMID:Caspase-1 is not involved in CD95/Fas-induced apoptosis in Jurkat T cells. 992 65

Apoptosis and particularly Fas-mediated apoptosis has been proposed to play a key role in controlling monocyte homeostasis. We and others have documented the regulatory function of human growth hormone (hGH) on monocytic cells, which prompted us to investigate the role of hGH on their response to Fas antigen cross-linking. Using human promonocytic U937 cells constitutively producing hGH upon gene transfer and human primary monocytes cultured in the presence of recombinant hGH, we demonstrated that hGH diminished Fas-mediated cell death by enhancing the expression of the antiapoptotic oncoprotein Bcl-2 as well as the level of bcl-2alpha mRNA. In parallel, we established that overexpression of Bcl-2 through gene transfer into normal U937 cells also diminished Fas-induced apoptosis. Further, as a result of Bcl-2 overexpression, we found that hGH greatly depressed Fas-induced activation of the cysteine protease caspase-3 (CPP32), which in turn affected the cleavage of poly(ADP-ribose) polymerase. Altogether, these data provide evidence that hGH mediates its protective effect through a Bcl-2-dependent pathway, clearly a crucial step in enhanced survival of monocytic cells exposed to Fas-induced death.
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PMID:Growth hormone prevents human monocytic cells from Fas-mediated apoptosis by up-regulating Bcl-2 expression. 993 16

We investigated the expression of Fas antigen (CD95) in the pure erythroid cell line AS-E2 in the presence and absence of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). TNF-alpha induced apoptosis in AS-E2 cells, whereas IFN-gamma did not. In culture containing no IFN-gamma or TNF-alpha, AS-E2 cells expressed little Fas antigen. However, IFN-gamma and IFN-gamma and TNF-alpha both induced expression of Fas antigen and its mRNA within 24 hours after the stimulation. When anti-Fas monoclonal antibody (IgM) was added to AS-E2 cells after the induction of Fas expression, AS-E2 cells underwent apoptosis as shown by the induction of DNA fragmentation. This apoptotic change was inhibited by an inhibitor of caspase-3-like proteases (Ac-DEVD-CHO) and an inhibitor of CED-3/ICE family proteases (Z-Asp-CH2-DCB) but not by an inhibitor of caspase-1-like proteases (Ac-YVAD-CHO), suggesting a role for caspase-3-like proteases in Fas-receptor signaling. Although AS-E2 cells expressed Fas ligand mRNA, treatment with ZB4, an antibody that inhibits Fas-mediated cell death, failed to suppress IFN-gamma- or TNF-alpha-mediated cytotoxicity. These findings suggest that the late erythroid progenitor cells are negatively regulated by IFN-gamma and TNF-alpha, both of which are capable of inducing functional Fas expression.
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PMID:Fas antigen (CD95) in pure erythroid cell line AS-E2 is induced by interferon-gamma and tumor necrosis factor-alpha and potentiates apoptotic death. 1008 5

Apoptosis is a genetically programmed cell death that is required for morphogenesis during embryogenic development and for tissue homeostasis in adult organisms. In most cases, apoptosis involves cytochrome c release from mitochondria. In the cytosol, cytochrome c combines with APAF-1 in the presence of ATP to activate caspase-9 that, in turn, activates effectors caspases such as caspase-3. Bcl-2 and related proteins control cytochrome c release from the mitochondria whereas IAP (for Inhibitor of APoptosis) molecules modulate the activity of caspases. Plasma membrane receptors such as Fas (CD95, APO-1), characterized by a so-called "death domain" in their cytoplasmic domain, can activate the caspase cascade through adaptator molecules such as FADD (Fas-Associated protein with a Death Domain). Dysregulation of the apoptotic machinery plays a role in the pathogenesis of various diseases and molecules involved in cell death pathways are potential therapeutic targets in immunologic, neurologic, cancer, infectious and inflammatory diseases.
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PMID:[Apoptosis: molecular mechanisms]. 1010 3

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.
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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

Susceptibility to CD95 (Fas/APO-1)-mediated apoptosis in human glioma cells depends on CD95 expression and unknown factors that regulate signal transduction. Thus, LN-18 cells are highly sensitive to CD95 ligand (CD95L) whereas LN-229 cells require coexposure to inhibitors of RNA or protein synthesis for induction of apoptosis. Here, we report that caspase 8 and 3 activation, poly(ADP-ribose)polymerase cleavage and apoptosis are inhibited by the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), or ectopic expression of crm-A or bcl-2. CD95L-induced glioma cell apoptosis does not involve ceramide generation. Apoptosis induced by exogenous ceramide resembles CD95-mediated apoptosis in that bcl-2 is protective but differs in that NDGA and crm-A have no effect and in that cycloheximide (CHX) inhibits rather than potentiates ceramide-induced cell death. We conclude that caspase 8 and caspase 3 activation, but not ceramide generation, are required for CD95 ligand-induced apoptosis of glioma cells and that bcl-2, crm-A and NDGA all act upstream of caspases to inhibit apoptosis.
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PMID:Crm-A, bcl-2 and NDGA inhibit CD95L-induced apoptosis of malignant glioma cells at the level of caspase 8 processing. 1020 95


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