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

To dissect intracellular pathways involved in B cell Ag receptor (BCR)-mediated and Fas-induced human B cell death, we isolated clones of the Burkitt lymphoma cell line Ramos with different apoptosis sensitivities. Selection for sensitivity to Fas-induced apoptosis also selected for clones with enhanced BCR death sensitivity and vice versa. In contrast, clones resistant to Fas-mediated apoptosis could still undergo BCR-induced cell death. Based on the functional phenotypes of these clones, we hypothesized that both receptor-induced apoptosis pathways are initially distinct but may eventually converge. Indeed, ligation of both Fas and BCR resulted in cleavage of the IL-1beta-converting enzyme/Ced-3-like protease caspase 3 and its substrates Ac-Asp-Glu-Val-Asp-aldehyde and poly(ADP-ribose) polymerase. Markedly, qualitative differences in the caspase 3 cleavage pattern induced by Fas or BCR ligation were observed; whereas Fas ligation generated caspase 3 cleavage products of 19/20 and 17 kDa, only the latter cleavage product was found upon BCR cross-linking. The caspase inhibitor Val-Ala-Asp-fluoromethylketone blocked both Fas- and BCR-mediated apoptosis, but differentially affected caspase 3 cleavage induced by either stimulus. Finally, overexpression of a Fas-associated death domain (FADD) dominant-negative mutant protein was found to inhibit Fas-induced apoptosis but not BCR-induced apoptosis. Together our findings imply that Fas and BCR couple, via FADD-dependent and FADD-independent mechanisms, respectively, to distinct proteases upstream of caspase 3.
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PMID:Dissection of pathways leading to antigen receptor-induced and Fas/CD95-induced apoptosis in human B cells. 963 25

Cells of the Epstein-Barr virus genome-negative Ramos-Burkitt lymphoma (Ramos-BL) B cell line can be rescued from antigen receptor (AgR)-triggered growth inhibition and apoptosis by signals transduced through their surface CD40. This study investigates whether phosphatidylinositol 3-kinase (PI3-kinase), which has been reported to be intimately involved in the regulation of normal and neoplastic cell growth, plays a role in CD40-promoted Ramos-BL B cell survival and uses the selective and reversible PI3-kinase inhibitor, LY294002 (LY). LY-mediated inhibition of PI3-kinase activity triggers growth inhibition and leads to the processing of caspase-3, caspase-3-like activity, cleavage of the death substrate poly(ADP-ribose) polymerase (PARP), and apoptosis from the G1 phase of cell cycle. These data indicate that constitutive PI3-kinase activity is critical for Ramos-BL B cell progression through the cell cycle such that if this PI3-kinase-dependent pathway(s) is inhibited, the cells default to apoptosis. Signals transduced through CD40 abrogate LY-triggered caspase-3-like activity and PARP cleavage but fail to inhibit LY-triggered growth inhibition, processing of caspase-3, and apoptosis. Likewise, in the presence of LY, signals transduced through CD40 abrogate AgR-triggered caspase-3-like activity and PARP cleavage but fail to inhibit AgR-triggered growth inhibition, caspase-3 processing, and apoptosis. The LY-mediated induction of growth inhibition and apoptosis occurs in the presence of the CD40-induced anti-apoptotic protein Bcl-XL. Taken together these data indicate that the CD40 of Ramos BL B cells is linked to PI3-kinase-independent and -dependent routes of survival: CD40-mediated inhibition of AgR-triggered caspase-3-like activity, PARP cleavage, and CD40-triggered Bcl-XL expression are PI3-kinase-independent, whereas PI3-kinase is critical for CD40-mediated rescue of this cellular population from AgR-triggered growth inhibition, caspase-3 processing, and apoptosis.
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PMID:LY294002-mediated inhibition of phosphatidylinositol 3-kinase activity triggers growth inhibition and apoptosis in CD40-triggered Ramos-Burkitt lymphoma B cells. 973 95

Apoptosis or programmed cell death is essential in the process of controlling lymphocyte growth and selection. We identified proteins that are involved in anti-IgM antibody-mediated apoptosis using a subclone of the human Burkitt lymphoma cell line BL60. Apoptosis-associated proteins were detected by high resolution two-dimensional gel electrophoresis on a micropreparative scale. Comparison of the high resolution two-dimensional gel electrophoresis protein patterns from apoptotic and non-apoptotic cells showed differences in approximately 80 spots including protein modifications. Analysis of the predominantly altered proteins was performed by internal Edman microsequencing and/or by peptide mass fingerprinting using matrix-assisted laser desorption/ionization mass spectrometry. Analysis was significantly improved by using new micropreparative high resolution two-dimensional gels employing high protein concentrations. The following 12 apoptosis-associated proteins were identified: heterogeneous nuclear ribonucleoprotein (hnRNP) A1, hnRNP C1/C2, FUSE-binding protein, dUTPase, lymphocyte-specific protein LSP1, UV excision repair protein RAD23 homologue B (HHR23B), 60 S acidic ribosomal protein P0 (L10E), heterochromatin protein 1 homologue alpha (HP1alpha), nucleolin, lamin, neutral calponin, and actin. Fragmentation of actin, hnRNP A1, hnRNP C1/C2, 60 S acidic ribosomal protein P0, lamin, and nucleolin could be inhibited by benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone, a selective irreversible inhibitor of CPP32 (caspase 3).
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PMID:Identification of apoptosis-associated proteins in a human Burkitt lymphoma cell line. Cleavage of heterogeneous nuclear ribonucleoprotein A1 by caspase 3. 977 22

Apoptosis is instrumental in the processes generating the diversity of the B-cell repertoire. Autoreactive B-cells are eliminated by anti-IgM crosslinking after encountering self-antigens, but precise mechanisms leading to B-cell apoptosis are still not well understood. We report here the cleavage of the transcription factor SP1 in the human Burkitt lymphoma cell line BL60 during anti-IgM-induced apoptosis. Western blot analysis revealed two cleavage products of approximately 68 kDa and 45 kDa after induction of apoptosis. Cleavage could be completely inhibited by zDEVD-fmk, an inhibitor specific for caspase 3-like proteases. In-vitro cleavage of recombinant SP1 by recombinant caspase 3 (CPP32) or caspase 7 (Mch 3) results in similar cleavage products as those observed in vivo. Recombinant caspase 6 (Mch 2) primarily generates a 68-kDa cleavage product, as observed after calcium ionophore (CaI) induced B-cell apoptosis. In contrast, caspase 1 (ICE) did not cleave SP1 in vitro. The time course of SP1 cleavage during anti-IgM-induced apoptosis is paralleled by an increase of caspase activity measured by DEVD-p-nitroanilide (DEVD-pNA) cleavage. DNA band-shift assays revealed a decrease in the intensity of the full length SP1/DNA complex and an increase in the intensity of a smaller complex due to the binding of one SP1 cleavage product. By Edman sequencing we could identify a caspase 3 cleavage site after Asp584 (D584AQPQAGR), generating a 22-kDa C-terminal SP1 protein fragment which still contains the DNA binding site. Our results show the cleavage of the human transcription factor SP1 in vivo and in vitro, underlining the central role of caspase 3-like proteases during the process of anti-IgM-induced apoptosis.
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PMID:Cleavage of transcription factor SP1 by caspases during anti-IgM-induced B-cell apoptosis. 1010 59

The p21(WAF1) (p21) cyclin-dependent kinase inhibitor plays a major role in regulating cell cycle arrest. It was recently reported that the p53-independent elevation of p21 protein levels is essential in mediating the G(1) arrest resulting from signal transduction events initiated by the crosslinking of membrane IgM on Daudi Burkitt lymphoma cells. Although the role of p21 in cell cycle regulation is well documented, there is little information concerning its role in antibody-mediated apoptosis. In the present study, we examined the involvement of p21 in the regulation of apoptosis by suppressing its induction in anti-IgM-treated Daudi cells through a p21 antisense expression construct approach. Reduction in induced p21 protein levels resulted in diminished G(1) arrest and increased apoptosis. The increased susceptibility to anti-IgM-mediated apoptosis was associated with increased caspase-3-like activity and poly-(ADP)ribose polymerase cleavage. These data suggest that p21 may directly interfere with the caspase cascade, thus playing a dual role in regulating both cell cycle progression and apoptosis.
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PMID:Cancer dormancy and cell signaling: induction of p21(waf1) initiated by membrane IgM engagement increases survival of B lymphoma cells. 1041 40

Divalent cations, including Zinc and Manganese ions, are important modulators of cell activation. We investigated the ability of these two divalent cations to modulate apoptosis in human Burkitt lymphoma B cells line (Ramos). We found that Zinc (from 10 to 50 microM) inhibited Manganese-induced caspase-3 activation and apoptosis of Ramos cells. Higher concentration of Zinc (50 to 100 microM) did not prevent Manganese-mediated apoptosis but rather increased cell death among Ramos cells. This Zinc-mediated cell death was associated with apoptotic features such as cell shrinkage, the presence of phosphatidylserine residues on the outer leaflet of the cells, chromatin condensation, DNA fragmentation and decrease of mitochondrial transmembrane potential. Zinc-mediated apoptosis was associated with caspase-9 and caspase-3 activation as revealed by the appearance of active p35 fragment of caspase-9 and p19 and p17 of caspase-3 as well as in vivo cleavage of PARP and of a cell-permeable fluorogenic caspase-3 substrate (Phiphilux-G(1)D(2)). Both Zinc-mediated apoptosis and caspase-3 activation were prevented by the cell-permeable, broad-spectrum inhibitor of caspases (zVAD-fmk) or overexpression of bcl-2. In addition, we show that Zinc-induced loss of transmembrane mitochondrial potential is a caspase-independent event, since it is not modified by the presence of zVAD-fmk, which is inhibited by overexpression of bcl-2. These results indicate that depending on its concentration, Zinc can exert opposite effects on caspase-3 activation and apoptosis in human B lymphoma cells: concentrations below 50 microM inhibit caspase-3 activation and apoptosis whereas higher concentrations of Zinc activate a death pathway associated with apoptotic-like features and caspase-3 activation.
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PMID:Zinc-mediated regulation of caspases activity: dose-dependent inhibition or activation of caspase-3 in the human Burkitt lymphoma B cells (Ramos). 1131 17

In vitro studies indicate that in lymphomas, execution of apoptosis involves activation of effector caspases. To investigate activation of effector caspases in vivo in biopsy specimens of lymphomas, a new assay was developed using antibodies against active caspase 3 and p89, a protein fragment generated by caspase-specific cleavage of poly-ADP ribose polymerase (PARP). Using this assay, it was found that in B-cell lymphomas, levels of active caspase 3/p89-positive cells correlate strongly with morphologically recognizable apoptotic cells. The number of active caspase 3/p89-positive cells was low in follicular lymphomas and usually high in diffuse large cell lymphomas. Highest numbers were found in Burkitt lymphomas and in two biopsies of diffuse large B-cell lymphomas (DLCLs) obtained several days after initiation of therapy. It is concluded that apoptosis in reactive lymphoid tissues and in B-cell lymphomas always involves activation of effector caspase 3 and cleavage of one of the major effector caspase substrates, PARP-1. Moreover, levels of effector caspase activation are constantly low in low-grade follicular lymphomas and vary considerably in DLCL and Burkitt lymphoma.
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PMID:Apoptosis in B-cell lymphomas and reactive lymphoid tissues always involves activation of caspase 3 as determined by a new in situ detection method. 1185 94

Cross-linking of the B cell antigen receptor (BCR) on germinal center B cells can induce growth arrest and apoptosis, thereby eliminating potentially autoreactive B cells. Using the Burkitt lymphoma cell line Ramos as a model, we studied the commitment to apoptosis following growth arrest, as well as how triggering of CD40 or addition of tumor necrosis factor (TNF)-alpha can interfere to block cell death. Both BCR triggering and direct induction of growth arrest by sodium butyrate (n-But) caused hypophosphorylation of the retinoblastoma protein (pRb), followed by apoptosis. Interestingly, although CD40 ligation or TNF-alpha efficiently prevented BCR-induced and n-But-induced apoptosis, these co-stimuli did not inhibit, but rather augmented, growth arrest. Analysis of cell cycle regulators showed that each apoptotic and T(h) stimulus distinctly affected cyclins or cyclin-dependent kinase inhibitors, indicating that growth arrest can be uncoupled from apoptosis. BCR ligation and growth arrest activated the intrinsic or mitochondrial route of apoptosis. CD40 ligation and TNF-alpha prevented release of cytochrome c and activation of caspase-3, which could not be explained by effects on the expression of Bcl-2, Bcl-x(L) or Bax. Finally, the onset of BCR-induced apoptosis occurred after 10-12 h and addition of CD40 mAb or TNF-alpha at that point still prevented further execution of apoptosis. We conclude that in mature B cells apoptosis is not an obligatory event following growth arrest. Instead, commitment to apoptosis can be rapidly controlled by T cells via CD40 ligand and TNF-alpha, downstream of the pRb-regulated restriction point of the cell cycle, but prior to mitochondrial cytochrome c release.
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PMID:Prevention of B cell antigen receptor-induced apoptosis by ligation of CD40 occurs downstream of cell cycle regulation. 1220 95

We demonstrate here that selective activation of endogenous members of the caspase family and cleavage of substrates responsible for the maintenance of nuclear functional and structural integrity are major effectors of antigen receptor (AgR)- and ionomycin-triggered apoptosis in Ramos-Burkitt lymphoma (Ramos-BL) B cells. Ramos-BL B cells express significant proenzyme levels of caspase-2, -3, -7 and -8, low levels of caspase-6 and are caspase-1-negative. However, while anti-IgM and ionomycin trigger for significant activation of caspase-3, -7 and -8 at 12-16 h and at 4 h post-stimulation respectively, both anti-IgM and ionomycin fail to activate caspase-2 indicating that AgR- and ionomycin-triggered Ramos-BL B cell apoptosis is mediated by the selective activation of, at least, caspase-3, -7 and -8. Anti-IgM triggers for cleavage of the resident nuclear proteins poly(ADP-ribose) polymerase (PARP) at 8 h, lamins B1 and B2 from 12 to 16 h; likewise, ionomycin triggers for degradation of PARP at 2 h, lamins B1 and B2 at 4 h. Signal transduction through CD40 rescues Ramos-BL B cells from AgR- and ionomycin-triggered apoptosis at a very early stage of the apoptotic process by inhibiting both the early cleavage of PARP as well as the activation of caspase-3, -7 and -8 and cleavage of lamin B1; CD40-mediated rescue occurs upstream of CD40-induced expression of Bcl-2 and increased expression of Bcl-xL. In such cellular populations subject to regulation through apoptosis, dysregulation of the apoptotic mechanisms can have devastating consequences by contributing to the pathogenesis of malignancy as well as to lymphoproliferative and autoantibody disorders. An understanding of the role played by caspases in the execution of apoptosis may provide insight into the pathogenesis of these disease states and thereby provide targets for novel therapeutic strategy.
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PMID:Temporal ordering of caspase activation and substrate cleavage during antigen receptor-triggered apoptosis in Ramos-Burkitt lymphoma B cells. 1285 74

Ramos-Burkitt lymphoma (Ramos-BL) B cell line is a neoplastic model of normal B cell selection by apoptosis at the germinal center site during maturation of the humoral immune response and can be triggered into apoptosis by cross-linking their surface antigen receptor with antibodies directed against immunoglobulin (Ig)M (anti-IgM) or by treating with the calcium ionophore ionomycin. We have recently demonstrated that anti-IgM and ionomycin trigger significant activation of caspase-3, -7 and -8 and for cleavage of the resident nuclear proteins poly(ADP-ribose) polymerase (PARP) and lamin B1 in Ramos-BL B cells, suggesting that these caspases may be localized to the nucleus as well as to the cytoplasm of Ramos-BL B cells. In order to examine this hypothesis further, we fractionated Ramos-BL B cells into their cytosolic and nuclear components and examined for expression of the endogenous proform and active large subunit of caspase-3; procaspase-3 and its active p17 large subunit were identified in both the cytosolic and nuclear fractions of Ramos-BL B cells. Immunofluorescence staining together with ordinary and confocal microscopy confirmed the observations that procaspase-3 immunoreactivity was clearly identified in the cytoplasm and nucleus while Fas ligand staining was localized to the cell surface and PARP immunoactivity to the nucleus, which were used as controls; procaspase-3 exhibited granular nuclear immunoreactivity whereas PARP displayed diffuse nuclear immunoreactivity; both of which was more intense in the internucleolar regions. Taken together, we now present evidence that procaspases and their active large subunits are found in both the cytoplasm and the nucleus and that procaspases localized not only in the cytoplasm but also in the nucleus are activated following application of apoptotic stimulus in Ramos-BL B cells.
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PMID:Procaspase-3 and its active large subunit localized in both cytoplasm and nucleus are activated following application of apoptotic stimulus in Ramos-Burkitt lymphoma B cells. 1288 46


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