Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activation of CD40 is essential for thymus-dependent humoral immune responses and rescuing B cells from apoptosis. Many of the effects of CD40 are believed to be achieved through altered gene expression. In addition to Bcl-x, a known CD40-regulated antiapoptotic molecule, we identified a related antiapoptotic molecule, A1/Bfl-1, as a CD40-inducible gene. Inhibition of the NF-kappaB pathway by overexpression of a dominant-active inhibitor of NF-kappaB abolished CD40-induced up-regulation of both the Bfl-1 and Bcl-x genes and also eliminated the ability of CD40 to rescue Fas-induced cell death. Within the upstream promoter region of Bcl-x, a potential NF-kappaB-binding sequence was found to support NF-kappaB-dependent transcriptional activation. Furthermore, expression of physiological levels of Bcl-x protected B cells from Fas-mediated apoptosis in the absence of NF-kappaB signaling. Thus, our results suggest that CD40-mediated cell survival proceeds through NF-kappaB-dependent up-regulation of Bcl-2 family members.
 ...
PMID:NF-kappaB-mediated up-regulation of Bcl-x and Bfl-1/A1 is required for CD40 survival signaling in B lymphocytes. 1043 Sep 8

We have previously shown that malignant B cells from non-Hodgkin's lymphomas (NHL) are resistant to Fas-mediated apoptosis. To determine the mechanisms underlying this resistance, we analysed by Western blotting the expression of several apoptotic regulators, caspase 3, caspase 8, FADD and poly(ADP-ribose) polymerase (PARP) in fresh lymphoma cells, isolated from 16 B-NHL biopsy samples of different histological subtypes, and displaying variable levels of Fas expression. The profiles of expression of these apoptotic regulators were monitored in cell lysates at different times following Fas with or without CD40 stimulation. Expression of FADD and of the uncleaved forms of PARP, caspase 3 and caspase 8 were detected in all untreated NHL samples. Low levels of PARP cleavage were noted in three untreated samples. Fas stimulation alone induced neither significant apoptosis nor significant changes in the expression profiles of FADD, caspases 3 and 8 and PARP in the 16 samples, except for variations in FADD and caspase 8 expression levels in a minority of samples. Fas/CD40 co-stimulation induced apoptosis and cleavage of caspase 3, caspase 8 and PARP in the five NHLs tested; expression of FADD was not modified. Our results showed (1) that induction of apoptosis in B-NHLs by Fas/CD40 co-stimulation used the same caspase executioner machinery as the normal Fas pathway, and (2) that NHL cells which resisted Fas-mediated apoptosis displayed no defect in either expression or functionality of caspases 3 and 8, nor in FADD expression. The dysfunction underlying NHL resistance to apoptosis must therefore lie upstream of caspase 8, or could alternatively be influenced by anti-apoptotic regulators of the Bcl-2 family.
 ...
PMID:FADD expression and caspase activation in B-cell lymphomas resistant to Fas-mediated apoptosis. 1046 53

Modulating signal transduction pathways represents a promising approach for altering the biological behaviour of haemopoietic malignancies. B-cell chronic lymphocytic leukaemia (B-CLL) cells were treated in vitro with CD40-ligand (CD40L) (CD154) or the protein kinase C modulator Bryostatin-1, exploring the effects on: (a) sensitivity to apoptosis induction by chemotherapeutic drugs (fludarabine, dexamethasone) or anti-Fas antibody; (b) expression of apoptosis-regulatory proteins (Bcl-2, Bcl-X, Mcl-1, Bax, Bak, BAG-1, Flip, XIAP); (c) expression of cell surface co-stimulatory antigens (CD80 [B7.1]; CD54 [ICAM-1]; CD70); and (d) expression of immune modulatory receptors (CD27, CD40, CD95 [Fas]). CD40L and Bryostatin decreased both spontaneous and drug-induced apoptosis in most B-CLL specimens tested. Apoptosis resistance was associated with CD40L- and Bryostatin-induced elevations in the anti-apoptotic Bcl-2 family protein Mcl-1. CD40L also induced striking increases in the levels of the anti-apoptotic protein Bcl-XL in B-CLLs. CD40L stimulated increases in the surface expression of CD40, CD54, CD69, CD70, CD80 and CD95, whereas Bryostatin induced expression of CD40, CD54, CD69 and CD95 but not the co-stimulatory molecules CD70 and CD80. Despite elevations in the expression of CD95 (Fas), anti-Fas antibodies failed to induce apoptosis of CD40L- and Bryostatin-treated B-CLL cells. This Fas-resistance was associated with increased expression of the Fas-antagonist Flip in CD40L-treated, and with elevations in the caspase inhibitor XIAP in Bryostatin-treated B-CLLs. The potential anti-apoptotic properties of CD40L and Bryostatin should be taken into consideration when employing these agents in clinical trials involving patients with B-CLL.
 ...
PMID:Bryostatin and CD40-ligand enhance apoptosis resistance and induce expression of cell survival genes in B-cell chronic lymphocytic leukaemia. 1052 3

Engagement of the antigen receptor on murine immature B cells leads to growth arrest followed by apoptosis. Concomitant signaling through CD40 sustains proliferation and rescues the cells from apoptosis. We show here that cross-linking CD40 stimulates the expression of A1, a member of the anti-apoptotic Bcl-2 family, in primary murine B lymphocytes. CD40-dependent stimulation of A1 was confirmed in WEHI 231 cells, an immature murine B cell lymphoma line. We transduced WEHI 231 cells with a bicistronic recombinant retroviral vector coding for A1 and a chimeric selection marker comprising the enhanced yellow fluorescent protein and the zeocin resistance protein. A1-transduced WEHI 231 cells showed a significant higher survival rate after engagement of the antigen receptor. In contrast, constitutive expression of A1 did not abrogate anti-IgM-induced c-myc down-regulation. Consistent with this, A1 did not release anti-IgM-induced cell cycle arrest. Our data indicate that CD40-stimulated A1 expression permits WEHI 231 cells to survive in the presence of anti-IgM antibodies and suggests a protective role for A1 in antigen receptor-mediated apoptosis in B cells.
 ...
PMID:A1 expression is stimulated by CD40 in B cells and rescues WEHI 231 cells from anti-IgM-induced cell death. 1054 Mar 18

We investigated whether human monocyte-derived dendritic cells (DCs) differed from tonsillar B cells in the set of cell fate genes they express constitutively and in the way these genes are affected after CD40 ligation. In particular, Bcl-2, TNF receptor-associated factor-2 (TRAF2), and TRAF4 were clearly inducible via CD40 in B cells but not in DCs. DCs, unlike B cells, were induced to increase expression of IL-1beta, IL-1Ra, IL-8, IL-12 p40, RANTES, macrophage inflammatory protein-1alpha, and monocyte chemoattractant protein-1 after CD40 ligation. We next tested whether CD40-induced signaling pathways were different in DCs vs B cells. In DCs, as in B cells, CD40 ligation activated p38 mitogen-activated protein kinase (MAPK), its downstream target, MAPKAPK-2, and the c-Jun N-terminal kinase. The p38 MAPK-specific inhibitor, SB203580, blocked CD40-induced MAPKAPK-2 activation, but did not affect activation of c-Jun N-terminal kinase. Furthermore, unlike in B cells, extracellular signal-regulated kinase-1 and -2 were activated after CD40 ligation in DCs. SB203580 strongly blocked CD40-induced IL-12 p40 production in DCs at both mRNA and protein levels, while having minimal effect on CD40-induced expression of the chemokine RANTES. In contrast, no detectable IL-12 p40 protein was secreted in CD40-stimulated B cells. Furthermore, CD40-induced mRNA expression of cellular inhibitor of apoptosis protein-2 was also dependent on the p38 MAPK pathway in DCs and differed compared with that in B cells. In conclusion, CD40 induces distinct programs in DCs and B cells, and the set of p38 MAPK-dependent genes in DCs (IL-12 p40 and cellular inhibitor of apoptosis protein-2) is different from that in B cells (IL-10 and IL-1beta).
 ...
PMID:Differential role for p38 mitogen-activated protein kinase in regulating CD40-induced gene expression in dendritic cells and B cells. 1057 Feb 61

Thioredoxin (Trx) is a ubiquitous protein disulfide oxidoreductase with antioxidant, cytokine, and chemotactic properties. Previously, we showed that Trx, in synergy with interleukin 1 (IL-1), IL-2, IL-4, tumor necrosis factor alpha (TNF-alpha), and CD40-ligation induced S-phase entry and mitosis in normal B cells and B-type chronic lymphocytic leukemia (B-CLL) cells. The viability of B-CLL cells stimulated by these protocols is high, and it has been hypothesized that the overexpression of Bcl-2 found in B-CLL protects the cells from apoptosis in vitro and in vivo. In this study, we have analyzed the response of cells derived from 12 samples of patients with B-CLL to recombinant human Trx in spontaneous apoptosis, with special reference to the Bcl-2 expression. Long-term cultures of B-CLL clones showed significantly higher viability when supplemented with human Trx (P =.031), also exemplified with clones surviving more than 2 months. Short-term cultures of B-CLL cells exposed to 1 microg/mL of Trx for 1, 5, or 12 days maintained expression or delayed down-regulation of Bcl-2 compared with control cultures containing RPMI 1640 medium and 10% fetal calf serum only (P =.032,. 002,.026, respectively). All B-CLL cells expressed constitutive Trx at varying but low levels, in contrast to adult T-cell leukemias, which overexpress Trx, as previously reported. We found that Trx added to B-CLL cells increased in a dose-dependent fashion the release of TNF-alpha, which has been suggested to be an autocrine growth factor for these cells. In conclusion, we have found that human recombinant Trx induced TNF-alpha secretion, maintained Bcl-2, and reduced apoptosis in B-CLL cells. (Blood. 2000;95:1420-1426)
 ...
PMID:Thioredoxin prolongs survival of B-type chronic lymphocytic leukemia cells. 1066 20

Signals generated through CD28-B7 and CD40 ligand (CD40L)-CD40 interactions have been shown to be crucial for the induction of long-term allograft survivability. We have recently demonstrated that humanized anti-CD40L (hu5C8) prevents rejection of mismatched renal allografts in primates. To investigate potential mechanisms of CD40L-induced allograft acceptance, we coimmobilized hu5C8 with suboptimal amounts of anti-CD3 to stimulate CD4(+) T cells. We now report that anti-CD3/CD40L costimulation results in CD28-independent activation and subsequent deletion of resting T cells. Coligation of CD3 and CD40L increased expression of CD69, CD25, and CD54 on CD4(+) T cells. We also found that costimulation with anti-CD3/CD40L resulted in enhanced production of interleukin (IL)-10, interferon gamma, and tumor necrosis factor alpha but not IL-2 or IL-6. Interestingly, after several days, anti-CD3/CD40L-mediated activation was followed by apoptosis in a significant population of cells. Consistent with that observation, anti-CD3/CD40L did not enhance the antiapoptotic proteins Bcl-2 and Bcl-xL. Further, the addition of CD28 at 24 h failed to rescue those cells induced to die after costimulation with anti-CD3/CD40L. Together, these data suggest that the graft-sparing effect of hu5C8 in vivo may result in part from early and direct effects on CD4(+) T cells, including a vigorous induction of immunomodulatory cytokines and/or apoptosis of allograft-specific T cells.
 ...
PMID:CD40 ligand (CD154) triggers a short-term CD4(+) T cell activation response that results in secretion of immunomodulatory cytokines and apoptosis. 1068 57

CD40 activation is necessary for thymus-dependent humoral immune responses and rescuing both phenotypically immature WEHI-231 B lymphoma cells from B cell antigen receptor-induced cell death and germinal center B cells from spontaneous apoptosis. As some effects of CD40 are probably mediated by differences in gene expression, cDNA expression arrays and RNase protection assays were used to identify the anti-apoptotic Bcl-2 homolog A1 as a CD40-inducible gene in B cell lines and purified germinal center B cells. Sustained CD40-induced A1 upregulation correlated with CD40-mediated rescue of WEHI-231 cells from anti-IgM-induced apoptosis. Moreover, overexpression of A1 specifically protected WEHI-231 cells from anti-IgM-induced apoptosis but not cell death triggered by certain other stimuli.
 ...
PMID:The CD40-inducible Bcl-2 family member A1 protects B cells from antigen receptor-mediated apoptosis. 1071 83

The suppression of apoptosis is one mechanism by which tumours become drug resitant. Extracellular signals from the germinal centre (GC) of secondary lymphoid tissue can rescue B cells from physiological- and chemotherapy-induced apoptosis. Such survival signals include CD40 receptor ligation, interleukin-4 (IL-4) receptor stimulation and the interaction of the integrin ligand VCAM-1 with its receptor. The GC environment was modelled in vitro by providing B lymphoma cells with these survival signals. JLP119 B lymphoma cells underwent apoptosis after exposure to the topisomerase II inhibitor etoposide and this was dramatically reduced when the cells were cultured in the GC system. CD40 receptor ligation resulted in increased levels of Bcl-XL. Etoposide diminished the binding between Bax and Bcl-XL but this was restored by IL-4 and VCAM-1 triggered signals. These data demonstrate combined effects of three microenvironmental signals on the Bcl-2 family and illustrate the potential importance of such signalling pathways in drug resistance of tumour cells.
 ...
PMID:Survival signals within the tumour microenvironment suppress drug-induced apoptosis: lessons learned from B lymphomas. 1073 82

We recently developed a novel immunomodulating gene fusion protein, CTA1-DD, that combines the ADP-ribosylating ability of cholera toxin (CT) with a dimer of an Ig-binding fragment, D, of Staphylococcus aureus protein A. The CTA1-DD adjuvant was found to be nontoxic and greatly augmented T cell-dependent responses to soluble protein Ags after systemic as well as mucosal immunizations. Here we show that CTA1-DD does not appear to form immune complexes or bind to soluble Ig following injections, but, rather, it binds directly to B cells of all isotypes, including naive IgD+ cells. No binding was observed to macrophages or dendritic cells. Immunizations in FcepsilonR (common FcRgamma-chain)- and FcgammaRII-deficient mice demonstrated that CTA1-DD exerted unaltered enhancing effects, indicating that FcgammaR-expressing cells are not required for the adjuvant function. Whereas CT failed to augment Ab responses to high m.w. dextran B512 in athymic mice, CTA1-DD was highly efficient, demonstrating that T cell-independent responses were also enhanced by this adjuvant. In normal mice both CT and CTA1-DD, but not the enzymatically inactive CTA1-R7K-DD mutant, were efficient enhancers of T cell-dependent as well as T cell-independent responses, and both promoted germinal center formation following immunizations. Although CT augmented apoptosis in Ag receptor-activated B cells, CTA1-DD strongly counteracted apoptosis by inducing Bcl-2 in a dose-dependent manner, a mechanism that was independent of the CD19 coreceptor. However, in the presence of CD40 stimulation, apoptosis was low and unaffected by CT, suggesting that the adjuvant effect of CT is dependent on the presence of activated CD40 ligand-expressing T cells.
 ...
PMID:The ADP-ribosylating CTA1-DD adjuvant enhances T cell-dependent and independent responses by direct action on B cells involving anti-apoptotic Bcl-2- and germinal center-promoting effects. 1084 81


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