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)

The effects of an acidic environment on the induction of apoptosis by 42 degrees C hyperthermia were investigated. An acidic environment (pH 6.6) enhanced the hyperthermia-induced apoptosis in HL-60 human promyelocytic leukemia cells as judged by the DNA fragmentation, flow cytometric analysis of DNA content, and cleavage of poly(ADP-ribose) polymerase. Hyperthermia exerted no effect on the expression of Bcl-2 and Bax, regardless of the environmental acidity during heating. The time of increase in apoptosis after heating coincided with the time of decrease in the G1-phase cell population. It seemed that the increase in heat-induced apoptosis in HL-60 cells in an acidic environment was due to a direct increase in the proteolytic cleavage of poly(ADP-ribose) polymerase by acidic caspases without the involvement of Bcl-2 and Bax, and that heat-induced apoptosis occurred during G1 phase in HL-60 cells.
 ...
PMID:Apoptosis and perturbation of cell cycle progression in an acidic environment after hyperthermia. 963 68

The resistance to stress-induced apoptosis conferred by the thermotolerant state or by exogenous expression of HSP72 was measured in mouse embryo fibroblasts. The induction of thermotolerance protects cells from heat, tumor necrosis factor alpha (TNFalpha), and ceramide-induced apoptosis but not from ionizing radiation. Because the development of thermotolerance is associated with increased levels of heat shock proteins, we determined whether constitutive expression of one of the major inducible heat shock proteins, HSP72, could also protect cells from stress-induced apoptosis. Cells expressing constitutive HSP72 were shown to have significantly reduced levels of apoptosis after heat, TNFalpha, and ceramide but not after ionizing radiation. Activation of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) was found to be strongly inhibited in thermotolerant cells after heat shock but not after other stresses. Cells that constitutively express HSP72 did not demonstrate decreased SAPK/JNK activation after any of these stresses. Thus, factors other than HSP72 that are induced in the thermotolerant state are able to reduce activation of SAPK/JNK after heat stress. Notably, the level of activation of SAPK/JNK did not correlate with the amount of apoptosis detected after different stresses. Constitutive HSP72 expression inhibited poly(ADP-ribose) polymerase cleavage in cells after heat shock and TNFalpha but not after ceramide or ionizing radiation. The results suggest either that SAPK/JNK activation is not required for apoptosis in mouse embryo fibroblasts or that HSP72 acts downstream of SAPK/JNK. Furthermore, the data support the concept that caspase activity, which can be down-regulated by HSP72, is a crucial step in stress-induced apoptosis. Based on data presented here and elsewhere, we propose that the heat shock protein family can be classified as a class of anti-apoptotic genes, in addition to the Bcl-2 and inhibitor of apoptosis protein families of genes.
 ...
PMID:Heat shock protein 72 modulates pathways of stress-induced apoptosis. 964 82

The polyamine analogue, N1-ethyl-N11-[(cycloheptyl)methyl]-4,8-diazaundecane (CHENSpm)-induced programmed cell death in NCI H157 cells is accompanied by cytochrome c release, the loss of mitochondrial membrane potential, activation of caspase-3, caspase-mediated poly(ADP-ribose) polymerase cleavage, G2-M arrest, and DNA and nuclear fragmentation. Overexpression of Bcl-2 completely inhibits CHENSpm-induced cytochrome c release, caspase-3 activation, and poly(ADP-ribose) polymerase cleavage. However, Bcl-2 does not abrogate CHENSpm-induced programmed cell death. These results suggest that although cytochrome c release and activation of the caspase-3 protease cascade contribute to the rapid and efficient execution of apoptosis, a caspase cascade-independent pathway also exists and can be activated by CHENSpm treatment.
 ...
PMID:Unsymmetrically substituted polyamine analogue induces caspase-independent programmed cell death in Bcl-2-overexpressing cells. 966 78

Sulfur mustard (SM) induces vesication via poorly understood pathways. The blisters that are formed result primarily from the detachment of the epidermis from the dermis at the level of the basement membrane. In addition, there is toxicity to the basal cells, although no careful study has been performed to determine the precise mode of cell death biochemically. We describe here two potential mechanisms by which SM causes basal cell death and detachment: namely, induction of terminal differentiation and apoptosis. In the presence of 100 microM SM, terminal differentiation was rapidly induced in primary human keratinocytes that included the expression of the differentiation-specific markers K1 and K10 and the cross-linking of the cornified envelope precursor protein involucrin. The expression of the attachment protein, fibronectin, was also reduced in a time- and dose-dependent fashion. Features common to both differentiation and apoptosis were also induced in 100 microM SM, including the rapid induction of p53 and the reduction of Bcl-2. At higher concentrations of SM (i.e., 300 microM), formation of the characteristic nucleosome-sized DNA ladders, TUNEL-positive staining of cells, activation of the cysteine protease caspase-3/apopain, and cleavage of the death substrate poly(ADP-ribose) polymerase, were observed both in vivo and in vitro. Both the differentiation and the apoptotic processes appeared to be calmodulin dependent, because the calmodulin inhibitor W-7 blocked the expression of the differentiation-specific markers, as well as the apoptotic response, in a concentration-dependent fashion. In addition, the intracellular Ca2+ chelator, BAPTA-AM, blocked the differentiation response and attenuated the apoptotic response. These results suggest a strategy for designing inhibitors of SM vesication via the Ca2+-calmodulin or caspase-3/PARP pathway.
 ...
PMID:Sulfur mustard induces markers of terminal differentiation and apoptosis in keratinocytes via a Ca2+-calmodulin and caspase-dependent pathway. 966 88

Nitric oxide (NO) promotes apoptotic cell death in the mouse macrophage cell line RAW 264.7 and in the human promyelocytic leukaemia cell line U937, which exemplifies p53-dependent and p53-independent executive death pathways. Here, we followed the cleavage of two caspase substrates during NO-intoxication, assaying poly(ADP-ribose) polymerase and U1-70kDa small ribonucleoprotein (U1-70kDa) degradation. By using pharmacological inhibitors, we found that Z-aspartyl-2,6-dichlorobenzoyloxymethylketone (Z-Asp-CH2-DCB; 100 microM), a caspase-like protease inhibitor, completely blocked S-nitrosoglutathione (GSNO)-induced apoptosis in both RAW 264.7 and U937 cells (IC50 = 50 microM for RAW 264.7 macrophages vs. IC50 = 33 microM for U937 cells). Notably, a characterized caspase-3 (Ac-DEVD-CHO) inhibitor left NO-induced DNA fragmentation and the appearance of an apoptotic morphology unaltered, although completely blocking caspase-3 activity. However, Z-Asp-CH2-DCB suppressed protease-mediated U1-70kDa cleavage and DNA fragmentation in parallel. In contrast, poly(ADP-ribose) polymerase cleavage in U937 cells was only delayed by Z-Asp-CH2-DCB, while poly(ADP-ribose) polymerase digestion in RAW 264.7 macrophages proceeded unaltered. We further compared U1-70kDa and poly(ADP-ribose) polymerase cleavage in stably Bcl-2 transfected RAW 264.7 macrophages. Rbcl2-2, a Bcl-2 overexpressing clone, suppressed DNA fragmentation and U1-70kDa digestion in response to GSNO, although allowing delayed but complete poly(ADP-ribose) polymerase degradation. Conclusively, poly(ADP-ribose) polymerase cleavage not causatively coincided with the appearance of other apoptotic parameters. Our results suggest that NO-induced apoptosis demands a Z-Asp-CH2-DCB inhibitable caspase activity, most likely distinct from caspase-3 and caspase-1. NO-mediated executive apoptotic signaling results in U1-70kDa and poly(ADP-ribose) polymerase cleavage. Whereas U1-70kDa digestion closely correlates to the occurrence of apoptotic parameters such as DNA fragmentation or an apoptotic morphology, poly(ADP-ribose) polymerase-breakdown does not.
 ...
PMID:Protease activation during nitric oxide-induced apoptosis: comparison between poly(ADP-ribose) polymerase and U1-70kDa cleavage. 967 Nov 15

Caspases are aspartate-specific cysteine proteases that play a pivotal role in drug-induced cell death. We designed RT-PCR assays to analyse the expression of CASP-3, CASP-4, CASP-6 and the long and short isoforms of CASP-2 genes in human cells. These genes heterogeneously coexpress in leukemic cell lines and bone marrow samples from patients with de novo acute myelogenous leukemia at diagnosis. Treatment of U937 and HL60 leukemic cells and HT29 colon carcinoma cells with the topoisomerase II inhibitor etoposide upregulates CASP-2 and CASP-3 genes in these cells before inducing their apoptosis. This effect of etoposide is not observed in K562 cells and bcl-2-transfected U937 cells which are less sensitive to drug-induced apoptosis. Nuclear run-on experiments demonstrate that etoposide increases CASP gene transcription in U937 cells, an effect that is prevented by Bcl-2 overexpression. Upregulation of CASP genes is associated with an enhanced synthesis of related procaspases that precedes the appearance of apoptosis markers including caspase-3 activation, poly(ADP-ribose) polymerase cleavage and internucleosomal DNA fragmentation. These results suggest that the ability of tumor cells to upregulate CASP-2 and CASP-3 genes in response to cytotoxic drugs could be predictive of their sensitivity to drug-induced apoptosis.
 ...
PMID:Upregulation of CASP genes in human tumor cells undergoing etoposide-induced apoptosis. 967 9

Taxol, 1-beta-D-arabinofuranosylcytosine (ara-C), and etoposide induce apoptosis in HL-60 cells that is blocked by overexpression of Bcl-2 or Bcl-xL.A 60-amino acid "loop" domain of Bcl-2 and Bcl-xL that contains phosphorylation sites is known to negatively regulate their antiapoptotic function. In the present studies, Taxol-, ara-C-, or etoposide-induced apoptosis was examined in HL-60/Bcl-2delta and HL-60/Bcl-xLdelta cells that express the loop-deletional mutant cDNA constructs p19Bcl-2delta32-80 and p18Bcl-xLdelta26-83, respectively. This was compared with control HL-60/neo cells as well as HL-60/Bcl-2 and HL-60/Bcl-xL cells. The latter two cell lines overexpress full-length Bcl-2 and Bcl-xL, respectively. Immunoblot analyses showed that HL-60/neo and HL-60/Bcl-2delta cells express similar levels of p26Bcl-2. In contrast, as compared with HL-60/neo, HL-60/Bcl-xLdelta cells expressed significantly lower levels of p26Bcl-2. p29Bcl-xL and p21Bax levels were similar in all cell types. Exposure to etoposide (50 microM) or ara-C (100 microM) for 4 h induced apoptosis in HL-60/neo cells, but not in HL-60/Bcl-2, HL-60/Bcl-xL, HL-60/Bcl-2delta, or HL-60/Bcl-xLdelta cells. In contrast, Taxol treatment (500 nM for 24 h) triggered the molecular cascade of apoptosis, represented by the cytosolic increase of cytochrome c and poly(ADP-ribose) polymerase or the DNA fragmentation factor cleavage activity of caspase-3 in HL-60/neo cells as well as in HL-60/Bcl-xLdelta and HL-60/Bcl-2delta cells, but not in their counterparts overexpressing full-length Bcl-2 and Bcl-xL. Equal amounts of p26Bcl-2 were coimmunoprecipitated with apoptosis protease-activating factor 1 (APAF-1) in HL-60/neo and HL-60/Bcl-2delta cells, whereas a markedly higher level of p26Bcl-2 coimmunoprecipitated with APAF-1 in HL-60/Bcl-2 cells. In association with Taxol-induced apoptosis, the levels of Bcl-2 that were coimmunoprecipitated with APAF-1 declined in HL-60/neo and HL-60/Bcl-2delta cells. This was not observed in HL-60/Bcl-2 cells, in which Taxol-induced apoptosis was blocked. Previous studies have demonstrated that Taxol induces phosphorylation of Bcl-2 in association with Taxol-induced apoptosis of HL-60/neo cells. Immunoblot analysis demonstrated a Taxol-induced mobility shift of Bcl-2 but not p19Bcl-2delta. Taxol also increased [32P]Pi incorporation in p26Bcl-2, but not in p19Bcl-2delta or p18Bcl-xL. These findings indicate that the loop domain is necessary for the Taxol-induced mobility shift and phosphorylation of Bcl-2. Loop domain also seems to be necessary for the antiapoptotic effect of Bcl-2 against Taxol-induced apoptosis but not ara-C- or etoposide-induced apoptosis.
 ...
PMID:"Loop" domain is necessary for taxol-induced mobility shift and phosphorylation of Bcl-2 as well as for inhibiting taxol-induced cytosolic accumulation of cytochrome c and apoptosis. 969 42

The requirement for caspases (ICE-like proteases) were investigated in mediating apoptosis of WEHI7.2 mouse lymphoma cells in response to two death inducers with different mechanisms of action, the glucocorticoid hormone dexamethasone (DX) and the calcium-ATPase inhibitor thapsigargin (TG). Apoptosis induction by these agents followed different kinetics, and was closely correlated with in vivo activation of caspase-3 (CPP32/Yama/Apopain) and cleavage of the caspase target protein poly(ADP-ribose) polymerase (PARP). Caspase activation and PARP cleavage were inhibited by Bcl-2 overexpression. Cell extracts from DX- and TG-treated cells cleaved the in vitro synthesized baculovirus p35 ICE-like protease target, producing 25 and 10 kDa fragments. p35 cleavage was inhibited by mutating the active site aspartic acid to alanine, and by a panel of protease inhibitors that inhibit caspase-3-like proteases, including iodoacetamide, N-ethylmaleimide, and Ac-DEVD-cho. Treatment of cells in vivo with two cell permeant peptide fluoromethylketone inhibitors of caspase activity, Z-VAD-fmk and Z-DEVD-fmk, inhibited DX- and TG-induced apoptotic nuclear changes and maintained plasma membrane integrity, whereas the cathepsin inhibitor, Z-FA-fmk, and two calpain inhibitors failed to inhibit apoptosis. An unexpected observation was that due to the delayed time course of DX-induced apoptosis, optimal preservation of plasma membrane integrity was achieved by adding caspase inhibitors beginning 8 h after DX addition. In summary, the findings indicate that two diverse apoptosis-inducing signals converge into a common Bcl-2-regulated pathway that leads to caspase activation and apoptosis.
 ...
PMID:Apoptosis induction by the glucocorticoid hormone dexamethasone and the calcium-ATPase inhibitor thapsigargin involves Bc1-2 regulated caspase activation. 970 90

Numerous studies have demonstrated an association between polycyclic aromatic hydrocarbons (PAHs) and lymphocyte toxicity. The present study shows that, consistent with its effects on Ca2+ homeostasis, benzo[a]pyrene (BaP) induces apoptosis in Daudi cells. Terminal deoxynucleotidal transferase-mediated dUTP-biotin nick end labeling (TUNEL) analysis at 18 h revealed a significant increase in the number of cells undergoing apoptosis in response to BaP (75%), BaP-7, 8-dihydrodiol (110%), and BaP-7,8-9,10-diol epoxide (BPDE) (215%) over DMSO vehicle control cultures. By 36 h, the trend toward increasing numbers of apoptotic cells continued with the parent compound producing a 125% increase over control values and the 7, 8-dihydrodiol and BPDE metabolites producing 195% and 370% increases over controls, respectively. DNA fragmentation assays demonstrated the presence of internucleosomal cleavage products consistent with the increasing numbers of TUNEL-positive cells responding to PAHs at 18 and 36 h. Analysis of poly(ADP-ribose) polymerase (PARP) protein in BaP- and BaP-7,8-dihydrodiol-treated cells strongly suggested the involvement of cysteine proteases by the appearance of an 85-kD fragment derived from hydrolytic cleavage of PARP, a phenomenon that has been associated with apoptosis in many systems. Immunoblot analysis demonstrated that both BaP and its 7,8-dihydrodiol metabolite affected a pathway involving Bcl-2 and Bax cytosolic proteins. Daudi cells undergoing apoptosis at 36 h in response to 10 microM BaP, the parent compound, expressed moderately reduced amounts of Bcl-2 (78% of vehicle controls). At the same time point, the 7,8-dihydrodiol and BDPE metabolites at 3 microM resulted in Bcl-2 protein expression that was 52% of that seen in vehicle controls. Parallel samples analyzed for expression of Bax protein displayed a 130% increase over vehicle control in Bax expression in response to the parent compound, while the 7,8-dihydrodiol metabolite produced a 257% increase in Bax. Furthermore, the effects on increased Bax expression were observed as early as 3 h after PAH exposure. The apoptotic response to PAHs in Daudi cells was sensitive to 4-h pretreatment with 0.3 microM alpha-naphthoflavone (ANF), a known inhibitor of cytochrome P450. In TUNEL assays of cells exposed to PAHs following pretreatment with ANF, at 18 h there was a significant reduction in the number of cells undergoing apoptosis in response to ANF compared to cells that were not pretreated with the compound. The effect of the parent compound at 18 h was completely blocked with ANF pretreatment, while ANF exerted a relatively weaker, but significant, effect on BaP-7, 8-dihydrodiol-induced apoptosis. With regard to modulation of expression of apoptosis-related proteins, Bax expression was restored to that observed in vehicle-control cultures at all time points tested (3, 18, and 36 h). Bcl-2 expression was most responsive to ANF at later time points following PAH exposure (18 and 36 h); however, Bcl-2 appeared to be more sensitive to the effects of ANF alone. Taken together, these data suggest that modulation of Bcl-2 family proteins, perhaps secondary to altered Ca2+ homeostasis, plays an important role in human B cell apoptosis induced by BaP.
 ...
PMID:Apoptosis in Daudi human B cells in response to benzo[a]pyrene and benzo[a]pyrene-7,8-dihydrodiol. 970 13

Recent studies have demonstrated that Apaf-1 is the adaptor molecule which in the presence of cytosolic cytochrome c (cyt c) and dATP interacts with procaspase-9, resulting in the sequential cleavage and activity of caspase-9 and caspase-3, followed by apoptosis. In the present studies, we determined the effect of enforced overexpression of Apaf-1 on the apoptotic threshold in the human myeloid leukemia HL-60 cells. Our findings demonstrate that both transient and stable transfections resulted in a 2.5-fold higher expression of Apaf-1, which was associated with approximately a 5-fold increase in the percentage of apoptosis in the transfectants (HL-60/Apaf-1) as compared with the control HL-60/neo cells. In cells overexpressing either Bcl-2 or Bcl-xL, transient overexpression of Apaf-1 did not induce apoptosis. Stably overexpressing Apaf-1 levels significantly sensitized HL-60/Apaf-1 cells to apoptosis induced by clinically achievable concentrations of paclitaxel or etoposide (P < 0.01). This increase in paclitaxel- or etoposide-induced apoptosis of HL-60/Apaf-1 cells was not associated with any significant alterations in Bcl-2, Bcl-xL, Bax, Fas, or Fas ligand expression. It was, however, clearly associated with caspase-9 cleavage, as well as the poly(ADP-ribose) polymerase and DFF45 cleavage activity of caspase-3. Coexpression of the catalytically inactive, dominant-negative, mutant caspase-9, XIAP, or treatment with the caspase inhibitor, zVAD, significantly inhibited the increase in apoptosis of HL-60/Apaf-1 cells (P < 0.01). These data indicate that the intracellular levels of Apaf-1 is an important molecular determinant of the threshold for apoptosis induced by paclitaxel and etoposide.
 ...
PMID:Overexpression of Apaf-1 promotes apoptosis of untreated and paclitaxel- or etoposide-treated HL-60 cells. 978 1


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