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

It is known that Bcl-2 has a protective effect against neuronal ischemia. Some reports speculate anti-apoptotic function of Bcl-2 depends not on the expression level but on the phosphorylation state. We found induction of apoptosis and CPP32 activation by energy impairment (3-nitropropionic acid (3-NP)-treatment or glucose-deprivation) in the neuronally differentiated P19 cells. Time course study of cell viability following ischemic insults showed that the number of viable cells decreased along with the increase in the amount of dephosphorylated Bcl-2 without obvious quantitative alteration of the protein. Then, we generated differentiated P19 cells overexpressing wild-type Bcl-2 (P19/wt. Bcl-2) or phosphorylation-negative Bcl-2 mutant (P19/mut.Bcl-2), in which alanine was substituted for serine 70. When the cell viability was examined within 24 h, P19/mut.Bcl-2 was more vulnerable to energy impairment as compared with P19/wt.Bcl-2. In addition, overexpression of wild-type Bcl-2 inhibited DNA laddering and CPP32 activation induced by the insults, while that of mutant Bcl-2 did not. These findings suggest that the phosphorylation state, as well as the expression level, of Bcl-2 plays an important role to modulate its protective effect against ischemic insults.
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PMID:Dephosphorylation-induced decrease of anti-apoptotic function of Bcl-2 in neuronally differentiated P19 cells following ischemic insults. 1070 May 55

Our recent studies suggest that human squamous cell carcinoma of the head and neck (SCCHN) is capable of activating an intrinsic mechanism of programmed-cell death in interacting lymphocytes in situ and in vitro. The current study used Jurkat T-cell line as a model to investigate intracellular apoptotic events in T cells interacting with SCCHN. Apoptosis induced in T lymphocytes by tumor cells was in part Fas-mediated, since it was partially, but significantly, inhibited in the presence of anti-Fas ligand Ab or in Fas-resistant Jurkat cells. The synthetic caspase inhibitors, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK) and N-benzyloxycarbonyl-Asp-glu-Val-Asp-fluoromethyl ketone (Z-DEVD-FMK), effectively blocked apoptosis of Jurkat cells co-incubated with SCCHN cell lines, suggesting the involvement of caspases in tumor-induced apoptosis of lymphocytes. Overexpression of CrmA, an inhibitor of caspase-1 and caspase-8, partially inhibited tumor-induced T-cell death. Caspase-8 and caspase-3 were identified as effector molecules in the execution of tumor-induced T-cell death, since the proform enzymes were processed into active subunits during co-incubation of T cells with tumor cells. Furthermore, co-incubation with tumor cells resulted in cleavage of poly(ADP-ribose) polymerase (PARP), a common caspase-3 substrate, and in cleavage of TcR-zeta chain, shown by us to be a T-cell specific caspase-3 substrate. Overexpression of Bcl-2 did not provide protection of T cells from SCCHN-induced DNA degradation. Instead, the Bcl-2 protein was cleaved in the target T cells during their co-incubation with tumor cells. These findings demonstrate that tumor cells can trigger in T lymphocytes caspase-dependent apoptotic cascades, which are not effectively protected by Bcl-2. (Blood. 2000;95:2015-2023)
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PMID:Tumor-induced apoptosis of T lymphocytes: elucidation of intracellular apoptotic events. 1070 69

We have shown that reoxygenation of hypoxic rat kidney proximaltubule cells leads to apoptosis. This is mediated by translocation ofBax from the cytosol to mitochondria, accompanied by release ofmitochondrial cytochrome c (cyt.c). The present studyhas examined the proteolytic mechanisms responsible for apoptosisduring hypoxia-reoxygenation. Caspases were activated duringhypoxia, as shown by cleavage of fluorogenic peptide substrates. By5 h caspase-3-like activity to cleave carbobenzoxy-Asp-Glu-Val-Asp-7-amino-4-trifluoromethyl coumarin was increased approx. 30-fold. Thiswas accompanied by specific processing of pro-caspase-3, -8 and -9 intoactive forms. Caspase activation during hypoxia was blocked bycarbobenzoxy-Val-Ala-Asp-fluoromethyl ketone and overexpression of Bcl-2. Of particular interest, caspase activation was also suppressed bythe chymotryptic inhibitors N-tosyl-L-phenylalaninechloromethyl ketone (TPCK) and Ala-Pro-Phe chloromethyl ketone (APF),and the general serine protease inhibitor 4-(2-aminoethyl)benzenesulphonyl fluoride. Inhibition of caspase activationby these compounds resulted in arrest of apoptosis. On the other hand,the serine protease inhibitors did not prevent release of mitochondrialcyt.c during hypoxia, suggesting that these compounds blockeda critical step in post-mitochondrial caspase activation. Furtherstudies using an in vitro reconstitution model showedthat cyt. c/dATP stimulated caspase-9 processing and downstreamcaspase activation were significantly suppressed in the presence ofTPCK and APF. Based on these results, we speculate that serineproteases may be involved in post-mitochondrial apoptotic events thatlead to activation of the initiator, caspase-9.
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PMID:Serine protease inhibitors suppress cytochrome c-mediatedcaspase-9 activation and apoptosis during hypoxia-reoxygenation. 1076 69

Apoptosis is a process of active cell death and is characterized by activation of caspases, DNA fragmentation, and biochemical and morphological changes. To better understand apoptosis, we have characterized the dose- and time-dependent toxic effects of cadmium in Rat-1 fibroblasts. Staining of cells with phosphatidylserine (PS)-annexin V, Hoechst 33258 or Rhodamine 123 and Tunel assays showed that incubating cells with 10 microM cadmium induced a form of cell death exhibiting typical characteristics of apoptosis, including cell shrinkage, externalization of PS, loss of mitochondria membrane potential, nuclear condensation and DNA fragmentation. Expression of Bcl-2 or CrmA each suppressed cadmium-induced cell death although Bcl-2 was somewhat more effective than CrmA. In vitro assay of caspase activity carried out using poly(ADP-ribose) polymerase (PARP) as a substrate as well as intracellular caspase assays using a fluorigenic caspase-3 substrate confirmed that caspase-3 is activated in Rat-1 cells undergoing cadmium-induced apoptosis. Both Asp-Glu-Val-Asp-aldehyde (DEVD-cho) and Tyr-Val-Ala-Asp-chloromethylketone (YVAD-cmk), selective inhibitors of caspase-3 and caspase-1, respectively, suppressed significantly cadmium-induced cell death. However, the nonselective caspase inhibitor, z-Val-Ala-Asp-floromethylketone (zVAD-fmk), was the most efficacious agent, almost completely blocking cadmium-induced cell death. Taken together, these results demonstrate that as in other forms of apoptosis, caspases play a central role in cadmium-induced cell death.
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PMID:Cadmium induces caspase-mediated cell death: suppression by Bcl-2. 1077 Nov 29

Apoptosis is regulated by the action of the Bcl-2 family of proteins, which includes anti- and pro-apoptotic members such as Bcl-xS and Bax. These proteins may differ from each other in structure, mechanism of action and interactions with anti-apoptotic signaling. The mechanism whereby Bax induces cell death has been studied in some cellular systems, but the mechanism of Bcl-xS-induced apoptosis is largely unknown. In this study we investigated and compared the apoptotic effects of Bcl-xS and Bax in the pheochromocytoma cell line, PC12 (a useful model system for studying neuronal apoptosis), and the extent to which they are protected by the survival factor, nerve growth factor (NGF). PC12 cells express endogenous Bcl-xS, Bax and Bcl-xL proteins. Subcellular fractionation revealed that Bax is presented mainly in the cytosolic and the heavy membrane fractions, Bcl-xS is present only in the cytosol, and the anti-apoptotic protein Bcl-xL is located mainly in the heavy membrane fraction. In contrast to the cytosolic localization of endogenous Bcl-xS, the exogenously overexpressed Bcl-xS is localized to the mitochondria. Overexpression of Bcl-xS or Bax induces cell death in the transfected cells. The cell death induced by overexpression of Bcl-xS was inhibited by coexpression of Bcl-xS with Bcl-2 or Bcl-xL, or by treatment with the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoro-methylketone (Z-VAD-FMK) or with NGF. The Bcl-2 mutants deltaC22, which lacks the transmembrane domain, and G145A (mI-3) were able to inhibit the death-inducing effect of Bcl-xS. These results therefore suggest that the apoptotic pathway induced by overexpression of Bcl-xS in PC12 cells can be controlled by Bcl-2 and Bcl-xL, is mediated by caspases, and can be inhibited by the NGF signaling pathway. The Bax-induced cell death was inhibited by co-expression of Bax with Bcl-2 or Bcl-xL, but was not inhibited by Z-VAD-FMK, NGF, or the Bcl-2 ml-3 or deltaC22 mutants. These results therefore suggest that Bax induces a caspase-independent cell death pathway which is blocked by Bcl-2 but not by the NGF signaling pathway. They further suggest that Bcl-xS and Bax induce different cell death pathways in PC12 cells.
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PMID:Bcl-xS and Bax induce different apoptotic pathways in PC12 cells. 1077 12

Nitric oxide (NO) from (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1- ium-1,2-diolate (NOC-18) induces apoptosis in human leukemia HL-60 cells. This effect was prevented by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK), thereby implicating caspase activity in the process. NOC-18 treatment resulted in the activation of several caspases including caspase-3, -6, -8, and -9(-like) activities and the degradation of several caspase substrates such as nuclear lamins and SP120 (hnRNP-U/SAF-A). Moreover, release of cytochrome c from mitochondria was also observed during NOC-18-induced apoptosis. This change was substantially prevented by Z-VAD-FMK, thereby suggesting that the released cytochrome c might function not only as an initiator but also as an amplifier of the caspase cascade. Bid, a death agonist member of the Bcl-2 family, was processed by caspases following exposure of cells to NOC-18, supporting the above notion. Thus, NO-mediated apoptosis in HL-60 cells involves a caspase/cytochrome c-dependent mechanism.
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PMID:Caspase activation and cytochrome c release during HL-60 cell apoptosis induced by a nitric oxide donor. 1079 16

Apoptosis is a cell suicide mechanism that requires the activation of cellular death proteases for its induction. We examined whether the progress of apoptosis involves cleavage of phospholipase C-gamma1 (PLC-gamma1), which plays a pivotal role in mitogenic signaling pathway. Pretreatment of T leukemic Molt-4 cells with PLC inhibitors such as U-73122 or ET-18-OCH(3) potentiated etoposide-induced apoptosis in these cells. PLC-gamma1 was fragmented when Molt-4 cells were treated with several apoptotic stimuli such as etoposide, ceramides, and tumor necrosis factor alpha. Cleavage of PLC-gamma1 was blocked by overexpression of Bcl-2 and by specific inhibitors of caspases such as Z-DEVD-CH(2)F and YVAD-cmk. Purified caspase-3 and caspase-7, group II caspases, cleaved PLC-gamma1 in vitro and generated a cleavage product of the same size as that observed in vivo, suggesting that PLC-gamma1 is cleaved by group II caspases in vivo. From point mutagenesis studies, Ala-Glu-Pro-Asp(770) was identified to be a cleavage site within PLC-gamma1. Epidermal growth factor receptor (EGFR) -induced tyrosine phosphorylation of PLC-gamma1 resulted in resistance to cleavage by caspase-3 in vitro. Furthermore, cleaved PLC-gamma1 could not be tyrosine-phosphorylated by EGFR in vitro. In addition, tyrosine-phosphorylated PLC-gamma1 was not significantly cleaved during etoposide-induced apoptosis in Molt-4 cells. This suggests that the growth factor-induced tyrosine phosphorylation may suppress apoptosis-induced fragmentation of PLC-gamma1. We provide evidence for the biochemical relationship between PLC-gamma1-mediated signal pathway and apoptotic signal pathway, indicating that the defect of PLC-gamma1-mediated signaling pathway can facilitate an apoptotic progression.
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PMID:Proteolytic cleavage of phospholipase C-gamma1 during apoptosis in Molt-4 cells. 1083 29

TGF-beta is a potent inducer of apoptosis in many Burkitt's lymphoma (BL) cell lines. In this study, we characterize this apoptotic process in the EBV-negative BL41 cell line. Induction of apoptosis was detected as early as 8 h after TGF-beta treatment, as assayed by TUNEL and poly(ADP-ribose) polymerase cleavage. FACS analysis demonstrates that this proceeds predominately from the G1, but also from the G2/M phases of the cell cycle. We observed no early detectable changes in the steady-state levels of Bcl-2 and several of its family members after TGF-beta treatment. We detected cleavage of caspases 2, 3, 7, 8, and 9 into their active subunits. Consistent with the involvement of these enzymes in TGF-beta-mediated apoptosis, the broad spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(Ome)-flouromethylketone (ZVAD-fmk) blocked TGF-beta-induced apoptosis and revealed a G1 arrest in treated cells. Use of specific caspase inhibitors revealed that the induction of apoptosis is caspase 8 dependent, but caspase 3 independent. Activation of caspase 8 has been shown to be a critical event in death receptor-mediated apoptosis. However, TGF-beta treatment of BL41 cells was found not to affect the cell surface expression of Fas, TNF-R1, DR3, DR4, or DR5, or the steady-state expression levels of Fas ligand, TNF-R1, DR3, DR4, and DR5. Furthermore, blocking experiments indicated that TGF-beta-mediated apoptosis is not dependent on Fas ligand, TNF-alpha, tumor necrosis-like apoptosis-inducing ligand, or TNF-like weak inducer of apoptosis signaling. Therefore, it appears that TGF-beta induces apoptosis in BL cell lines via caspase 8 in a death receptor-independent fashion.
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PMID:Apoptosis induced by TGF-beta 1 in Burkitt's lymphoma cells is caspase 8 dependent but is death receptor independent. 1094 76

Dibucaine, a local anesthetic, inhibited the growth of promyelocytic leukemia cells (HL-60) without inducing arrest of the cell cycle and differentiation to granulocytes. Typical DNA fragmentation and DNA ladder formation were induced in a concentration- and time-dependent manner. The half-maximal concentration of dibucaine required to induce apoptosis was 100 microM. These effects were prevented completely by the pan-caspase inhibitor z-Val-Ala-Asp-(OMe)-fluoromethylketone (z-VAD-fmk), thereby implicating the cysteine aspartase (caspase) cascade in the process. Dibucaine activated various caspases, such as caspase-3, -6, -8, and -9 (-like) activities, but not caspase-1 (-like) activity, and induced mitochondrial membrane depolarization and the release of cytochrome c (Cyt.c) from mitochondria into the cytosol. Processing of pro-caspase-3, -8, and -9 by dibucaine was confirmed by western blot analysis. Bid, a death agonist member of the Bcl-2 family, was processed by caspases following exposure of cells to dibucaine. However, 100 microM dibucaine scarcely inhibited oxidative phosphorylation, but it induced membrane permeability transition in isolated rat liver mitochondria. Taken together, these data suggest that dibucaine induced apoptosis of HL-60 cells through activation of the caspase cascade in conjunction with Cyt.c release induced by a processed product of Bid and depolarization of the mitochondrial membrane potential.
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PMID:Mechanism of dibucaine-induced apoptosis in promyelocytic leukemia cells (HL-60). 1097 98

LIGHT is a member of the tumor necrosis factor superfamily and is the ligand for LT-betaR, HVEM, and decoy receptor 3. LIGHT has a cytotoxic effect, which is further enhanced by the presence of interferon-gamma (IFN-gamma). Although LIGHT/IFN-gamma can activate caspase activity, neither benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone nor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone can completely inhibit LIGHT/IFN-gamma-mediated apoptosis. Moreover, overexpression of Bcl-2 further enhances LIGHT/IFN-gamma-mediated apoptosis. It appears that LIGHT and IFN-gamma act synergistically to activate caspase-3, with the resultant cleavage of Bcl-2, removal of the BH4 domain, leading to conversion of Bcl-2 from an antiapoptotic to a proapoptotic form in p53-deficient hepatocellular carcinoma Hep3BT2 cells. Thus, LIGHT seems to be able to override the protective effect of Bcl-2 and induce cell death. Although benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone and benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone can prevent the cleavage of Bcl-2 by LIGHT/IFN-gamma, they only partially inhibit apoptosis in Hep3BT2 cells that are overexpressing Bcl-2. In contrast, both LIGHT/IFN-gamma-mediated apoptosis and Bcl-2 cleavage are inhibited by free radical scavengers, indicating that free radicals may play an essential role in LIGHT/IFN-gamma-mediated apoptosis at a step upstream of caspase-3 activation. These results suggest that LIGHT signaling may diverge into multiple, separate processes.
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PMID:Overexpression of bcl-2 enhances LIGHT- and interferon-gamma -mediated apoptosis in Hep3BT2 cells. 1099 81


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