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)

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.
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PMID:Apoptosis induction by the glucocorticoid hormone dexamethasone and the calcium-ATPase inhibitor thapsigargin involves Bc1-2 regulated caspase activation. 970 90

Cytochrome c release and the mitochondrial permeability transition (PT), including loss of the transmembrane potential (Deltapsi), play an important role in apoptosis. Using isolated mitochondria, we found that recombinant Bax and Bak, proapoptotic members of the Bcl-2 family, induced mitochondrial Deltapsi loss, swelling, and cytochrome c release. All of these changes were dependent on Ca2+ and were prevented by cyclosporin A (CsA) and bongkrekic acid, both of which close the PT pores (megachannels), indicating that Bax- and Bak-induced mitochondrial changes were mediated through the opening of these pores. Bax-induced mitochondrial changes were inhibited by recombinant Bcl-xL and transgene-derived Bcl-2, antiapoptotic members of the Bcl-2 family, as well as by oligomycin, suggesting a possible regulatory effect of F0F1-ATPase on Bax-induced mitochondrial changes. Proapoptotic Bax- and Bak-BH3 (Bcl-2 homology) peptides, but not a mutant BH3 peptide nor a mutant Bak lacking BH3, induced the mitochondrial changes, indicating an essential role of the BH3 region. A coimmunoprecipitation study revealed that Bax and Bak interacted with the voltage-dependent anion channel, which is a component of PT pores. Taken together, these findings suggest that proapoptotic Bcl-2 family proteins, including Bax and Bak, induce the mitochondrial PT and cytochrome c release by interacting with the PT pores.
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PMID:Bax interacts with the permeability transition pore to induce permeability transition and cytochrome c release in isolated mitochondria. 984 49

The proteins Bcl-2 and Bcl-X(L) prevent apoptosis, but their mechanism of action is unclear. We examined the role of Bcl-2 and Bcl-X(L) in the regulation of cytosolic Ca(2+), nitric oxide production (NO), c-Jun NH(2)-terminal kinase (JNK) activation, and apoptosis in Jurkat T cells. Thapsigargin (TG), an inhibitor of the endoplasmic reticulum-associated Ca(2+) ATPase, was used to disrupt Ca(2+) homeostasis. TG acutely elevated intracellular free Ca(2+) and mitochondrial Ca(2+) levels and induced NO production and apoptosis in Jurkat cells transfected with vector (JT/Neo). Buffering of this Ca(2+) response with 1, 2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester (BAPTA-AM) or inhibiting NO synthase activity with N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME) blocked TG-induced NO production and apoptosis in JT/Neo cells. By contrast, while TG produced comparable early changes in the Ca(2+) level (i.e., within 3 h) in Jurkat cells overexpressing Bcl-2 and Bcl-X(L) (JT/Bcl-2 or JT/Bcl-X(L)), NO production, late (36-h) Ca(2+) accumulation, and apoptosis were dramatically reduced compared to those in JT/Neo cells. Exposure of JT/Bcl-2 and JT/Bcl-X(L) cells to the NO donor, S-nitroso-N-acetylpenacillamine (SNAP) resulted in apoptosis comparable to that seen in JT/Neo cells. TG also activated the JNK pathway, which was blocked by L-NAME. Transient expression of a dominant negative mutant SEK1 (Lys-->Arg), an upstream kinase of JNK, prevented both TG-induced JNK activation and apoptosis. A dominant negative c-Jun mutant also reduced TG-induced apoptosis. Overexpression of Bcl-2 or Bcl-X(L) inhibited TG-induced loss in mitochondrial membrane potential, release of cytochrome c, and activation of caspase-3 and JNK. Inhibition of caspase-3 activation blocked TG-induced JNK activation, suggesting that JNK activation occurred downstream of caspase-3. Thus, TG-induced Ca(2+) release leads to NO generation followed by mitochondrial changes including cytochrome c release and caspase-3 activation. Caspase-3 activation leads to activation of the JNK pathway and apoptosis. In summary, Ca(2+)-dependent activation of NO production mediates apoptosis after TG exposure in JT/Neo cells. JT/Bcl-2 and JT/Bcl-X(L) cells are susceptible to NO-mediated apoptosis, but Bcl-2 and Bcl-X(L) protect the cells against TG-induced apoptosis by negatively regulating Ca(2+)-sensitive NO synthase activity or expression.
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PMID:Bcl-2 and Bcl-X(L) block thapsigargin-induced nitric oxide generation, c-Jun NH(2)-terminal kinase activity, and apoptosis. 1040 55

Calphostin C-mediated apoptosis in glioma cells was reported previously to be associated with down-regulation of Bcl-2 and Bcl-xL. In this study, we report that 100 nM calphostin C also induces translocation and integration of monomeric Bax into mitochondrial membrane, followed by cytochrome c release into cytosol and subsequent decrease of mitochondrial inner membrane potential (DeltaPsim) before activation of caspase-3. The integration of monomeric Bax was associated with acquirement of alkali-resistance. The translocated monomeric Bax was partly homodimerized after cytochrome c release and decrease of DeltaPsim. The translocation and homodimerization of Bax, cytochrome c release, and decrease of DeltaPsim were not blocked by 100 microM z-VAD.fmk, a pan-caspase inhibitor, but the homodimerization of Bax and decrease of DeltaPsim were inhibited by 10 microM oligomycin, a mitochondrial F0F1-ATPase inhibitor. Therefore, it would be assumed that mitochondrial release of cytochrome c results from translocation and integration of Bax and is independent of permeability transition of mitochondria and caspase activation, representing a critical step in calphostin C-induced cell death.
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PMID:Calphostin C-mediated translocation and integration of Bax into mitochondria induces cytochrome c release before mitochondrial dysfunction. 1082 74

The antiapoptotic protein Bcl-2 localizes not only to mitochondria but also to the endoplasmic reticulum (ER). However, the function of Bcl-2 at the level of the ER is poorly understood. In this study, we have investigated the effects of Bcl-2 expression on Ca(2+) storage and release by the ER. The expression of Bcl-2 decreased the amount of Ca(2+) that could be released from intracellular stores, regardless of the mode of store depletion, the cell type, or the species from which Bcl-2 was derived. Bcl-2 also decreased cellular Ca(2+) store content in the presence of mitochondrial inhibitors, suggesting that its effects were not mediated through mitochondrial Ca(2+) uptake. Direct measurements with ER-targeted Ca(2+)-sensitive fluorescent "cameleon" proteins revealed that Bcl-2 decreased the free Ca(2+) concentration within the lumen of the ER, [Ca(2+)](ER). Analysis of the kinetics of Ca(2+) store depletion in response to the Ca(2+)-ATPase inhibitor thapsigargin revealed that Bcl-2 increased the permeability of the ER membrane. These results suggest that Bcl-2 decreases the free Ca(2+) concentration within the ER lumen by increasing the Ca(2+) permeability of the ER membrane. The increased ER Ca(2+) permeability conferred by Bcl-2 would be compatible with an ion channel function of Bcl-2 at the level of the ER membrane.
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PMID:Bcl-2 decreases the free Ca2+ concentration within the endoplasmic reticulum. 1082 33

Apoptosis in murine haematopoietic interleukin (IL)3-dependent cell lines is induced within 6-8 h by IL-3 withdrawal. Direct introduction of cytochrome c by electroporation induces apoptosis within 2 h and was inhibited by caspase inhibitors, such as Z-VADfmk and Z-Dfmk. We report here that apoptosis induced by IL-3 withdrawal was refractory to these inhibitors but was accompanied by striking redistribution of mitochondria, which aggregated into an area associated with centrioles without loss of Deltapsim. Both mitochondrial redistribution and apoptosis were inhibited by the calcium ionophore, ionomycin. Nocodozole, an inhibitor of microtubule assembly, also induced apoptosis, which was unaffected by caspase inhibitors. Although nocodozole did not alter mitochondrial distribution, it significantly reduced Deltapsim, and both reduction of Deltapsim and apoptosis were inhibited by ionomycin. Oligomycin, which inhibits the mitochondrial FoF1 ATPase, similarly induced apoptosis, which was unaffected by caspase inhibitors but was inhibited by ionomycin. Further, oligomycin stimulated the novel formation and release of surface membrane-derived vesicles containing mitochondria with intact Deltapsim; ionomycin also inhibited their production. In all these conditions, Bcl-2 protected cells from apoptosis. Our studies show that apoptosis induced by three very different agents shares insensitivity to caspase inhibitors, suppression by ionomycin and effects on mitochondria, which all appear to be linked to cytoskeletal/microtubule activity. They suggest that microtubules and the cytoskeleton play an important role in apoptosis through mechanisms affecting mitochondria but which are independent of cytochrome c release.
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PMID:Apoptosis in factor-dependent haematopoietic cells is linked to calcium-sensitive mitochondrial rearrangements and cytoskeletal modulation. 1084 3

Cytokines such as interleukin-3 (IL-3) promote the survival of hematopoietic cells through mechanisms that are not well characterized. Withdrawal of IL-3 from an IL-3-dependent pro-B cell line induced early stress-related events that preceded cell death by more than 40 h. Intracellular pH rose above pH 7.8, peaking 2-3 h post-IL-3 withdrawal, and induced a transient increase in mitochondrial membrane potential (Delta Psi(m)) detected using several different dyes. Similar events were observed following IL-7 withdrawal from a different dependent cell line. Bcl-2, Bax, and caspases were unrelated to these early events. Intracellular alkaline pH inhibited the mitochondrial import of ADP, which would limit ATP synthesis. Total cellular ATP sharply declined during this early period, presumably as a consequence of suppressed ADP import. This was followed by an increase in reduced pyridine nucleotides. The transient increase in Delta Psi(m) was blocked by oligomycin, an inhibitor of F(0)F(1-)ATPase that may have undergone reversal caused by the abnormal ADP-ATP balance within mitochondria. These findings suggest a novel sequence of early events following trophic factor withdrawal in which alkaline pH inhibits ADP import into mitochondria, reversing the F(0)F(1-)ATPase, which in turn consumes ATP and pumps out protons, raising Delta Psi(m).
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PMID:Interleukin-3 withdrawal induces an early increase in mitochondrial membrane potential unrelated to the Bcl-2 family. Roles of intracellular pH, ADP transport, and F(0)F(1)-ATPase. 1110 40

We previously reported that concanamycin A, a specific inhibitor of vacuolar type H+-ATPases, induces DNA fragmentation in B cell hybridoma HS-72 cells. In the present study, we found that the cytosol from concanamycin A-treated HS-72 cells had a cytotoxic effect on intact cells in a cell viability assay. While activin A also induced apoptosis in HS-72 cells, the cytosol from activin A-treated HS-72 cells had no effect on cell viability. We purified the cytosol from concanamycin A-treated HS-72 cells by a four-step procedure: ultracentrifugation; HiTrap heparin column chromatography; HiTrap Q column chromatography; and reverse-phase high performance liquid chromatography on a C18 hydrophobic support. The biologically active fraction, which was used as partially purified cytosol, gave a specific band of protein with a molecular mass of 33 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The mechanism of cell death was examined by observing changes in nuclear morphology, an increase in the proportion of fragmented DNA, and the typical ladder pattern of degraded chromosomal DNA, indicating the induction of apoptosis in cells cultured with the partially purified cytosol. The overexpression of human Bcl-2 suppressed apoptosis, indicating that the cytosol from concanamycin A-treated HS-72 cells induces apoptosis by a Bcl-2-inhibiting mechanism. These findings suggest that concanamycin A, a vacuolar type H+-ATPase inhibitor, produces intracellular apoptosis-inducing factor in B cell hybridoma.
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PMID:Intracellular apoptosis-inducing factor is induced by a vacuolar type H+-ATPase inhibitor in B lineage cells. 1114 15

This work, using RT PCR, studied expression of mRNAs encoding ion transporters, the Na/H antiporter (NHE1), the beta subunit of the Na,K-ATPase pump (ATP1B1), the NaK2Cl symporter (NKCC1), and some proteins unrelated to ion transport: the serum and glucocorticoid dependent kinase (hSGK), beta-actin, a glycolytic enzyme (GAPDH), and regulators of proliferation and apoptosis (p53, Bcl-2) during activation of human lymphocytes with phytohemagglutinin for 4-24 h. Within 24 hours the mRNA levels of NHE1, beta-actin, Bcl-2, and p53 increased by more than 100%, the mRNA levels of ATP1B1, GAPDH, and hSGK, by about 50%, while the mRNA levels of NKCC1 decreased transiently. These results indicate a differential transcriptional control of NHE1, ATP1B1, and NKCC1 following a proliferative stimulus of human lymphocytes.
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PMID:Differential transcription of ion transporters, NHE1, ATP1B1, NKCC1 in human peripheral blood lymphocytes activated to proliferation. 1127 79

Thapsigargin (Tg), a selective inhibitor of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA), causes depletion of intracellular Ca(2+) stores, hence activation of capacitative Ca(2+) entry (CCE). Incubation of Xenopus laevis oocytes with Tg resulted in an increased rate of progesterone-induced meiotic maturation. Non-mitochondrial (45)Ca(2+) uptake by SERCA-containing microsomes prepared from control wild-type oocytes microinjected with sterile water was inhibited essentially 100% by Tg. However, overexpression of Bcl-2, an oncogene known to protect against Tg-induced apoptosis in certain cell types, resulted in only 40% inhibition of microsomal (45)Ca(2+) uptake by Tg while non-inhibited (45)Ca(2+) uptake remained unchanged. Moreover Bcl-2 overexpression also protected against inhibition of CCE. I(Cl(Ca)) was similar in Bcl-2-overexpressing and control oocytes when intracellular Ca(2+) store depletion was induced by microinjection of inositol 1,4,5-trisphosphate (InsP(3)) and other means and when CCE was induced by means independent of SERCA inhibition. Our data indicate that Bcl-2 affects neither the InsP(3) receptor nor Ca(2+) entry itself. At the end of a 24-h period after progesterone addition to the medium, only 25% of Bcl-2-overexpressing oocytes had matured compared to 85% of control oocytes. Our data suggest that SERCA participates in Xenopus oocyte maturation by controlling cytosolic Ca(2+) and/or intracellular Ca(2+) stores, hence CCE. An observed progesterone-dependent protein kinase-catalysed phosphorylation of SERCA is further indication of its role in oocyte maturation.
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PMID:Evidence for a role of the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase in thapsigargin and Bcl-2 induced changes in Xenopus laevis oocyte maturation. 1131 28


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