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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Apoptosis and survival of diverse cell types are under hormonal control, but intracellular mechanisms regulating cell death are unclear. The Bcl-2/Ced-9 family of proteins contains conserved Bcl-2 homology regions that mediate the formation of homo- or heterodimers important for enhancing or suppressing apoptosis. Unlike most other members of the Bcl-2 family, BAD (Bcl-xL/Bcl-2 associated death promoter), a death enhancer, has no C-terminal transmembrane domain for targeting to the outer mitochondrial membrane and nuclear envelope. We hypothesized that BAD, in addition to binding Bcl-xL and Bcl-2, may interact with proteins outside the Bcl-2 family. Using the yeast two-hybrid system to search for BAD-binding proteins in an ovarian fusion cDNA library, we identified multiple cDNA clones encoding different isoforms of 14-3-3, a group of evolutionally conserved proteins essential for signal transduction and cell cycle progression. Point mutation of BAD in one (S137A), but not the other (S113A), putative binding site found in diverse 14-3-3 interacting proteins abolished the interaction between BAD and 14-3-3 without affecting interactions between BAD and Bcl-2. Because the S137A BAD mutant presumably resembles an underphosphorylated form of BAD, we used this mutant to screen for additional BAD-interacting proteins in the yeast two-hybrid system. P11, a nerve growth factor-induced neurite extension factor and member of the calcium-binding S-100 protein family, interacted strongly with the mutant BAD but less effectively with the wild type protein. In Chinese hamster ovary (CHO) cells, transient expression of wild type BAD or its mutants increased apoptotic cell death, which was blocked by cotransfection with the baculovirus-derived cysteine protease inhibitor, P35. Cotransfection with 14-3-3 suppressed apoptosis induced by wild type or the S113A mutant BAD but not by the S137A mutant incapable of binding 14-3-3. Furthermore, cotransfection with P11 attenuated the proapoptotic effect of both wild type BAD and the S137A mutant. For both 14-3-3 and P11, direct binding to BAD was also demonstrated in vitro. These results suggest that both 14-3-3 and P11 may function as BAD-binding proteins to dampen its apoptotic activity. Because the 14-3-3 family of proteins could interact with key signaling proteins including Raf-1 kinase, protein kinase C, and phosphatidyl inositol 3 kinase, whereas P11 is an early response gene induced by the neuronal survival factor, nerve growth factor, the present findings suggest that BAD plays an important role in mediating communication between different signal transduction pathways regulated by hormonal signals and the apoptotic mechanism controlled by Bcl-2 family members.
Mol Endocrinol 1997 Nov
PMID:Interference of BAD (Bcl-xL/Bcl-2-associated death promoter)-induced apoptosis in mammalian cells by 14-3-3 isoforms and P11. 936 53

The Bcl-2 related protein Bad is a promoter of apoptosis and has been shown to dimerize with the anti-apoptotic proteins Bcl-2 and Bcl-XL. Overexpression of Bad in murine FL5.12 cells demonstrated that the protein not only could abrogate the protective capacity of coexpressed Bcl-XL but could accelerate the apoptotic response to a death signal when it was expressed in the absence of exogenous Bcl-XL. Using deletion analysis, we have identified the minimal domain in the murine Bad protein that can dimerize with Bcl-xL. A 26-amino-acid peptide within this domain, which showed significant homology to the alpha-helical BH3 domains of related apoptotic proteins like Bak and Bax, was found to be necessary and sufficient to bind Bcl-xL. To determine the role of dimerization in regulating the death-promoting activity of Bad and the death-inhibiting activity of Bcl-xL, mutations within the hydrophobic BH3-binding pocket in Bcl-xL that eliminated the ability of Bcl-xL to form a heterodimer with Bad were tested for the ability to promote cell survival in the presence of Bad. Several of these mutants retained the ability to impart protection against cell death regardless of the level of coexpressed Bad protein. These results suggest that BH3-containing proteins like Bad promote cell death by binding to antiapoptotic members of the Bcl-2 family and thus inhibiting their survival promoting functions.
Mol Cell Biol 1997 Dec
PMID:Bad is a BH3 domain-containing protein that forms an inactivating dimer with Bcl-XL. 937 35

The effects of the non-tumor-promoting protein kinase C (PKC) activator bryostatin 1 and the PKC inhibitors staurosporine and UCN-01 were examined with respect to modulation of 1-[beta-D-arabinofuranosyl]cytosine (ara-C)-induced apoptosis in human myeloid leukemia cells (HL-60) overexpressing the antiapoptotic protein Bcl-2. HL-60/Bcl-2 cells displayed a 5-fold increase in Bcl-2 protein compared with empty-vector counter-parts (HL-60/pCEP4) but comparable levels of Bax, Mcl-1, and Bcl-xL. After exposure to an equimolar concentration of ara-C (10 microM for 6 hr), HL-60/Bcl-2 cells were significantly less susceptible to apoptosis, DNA fragmentation, and loss of clonogenicity than HL-60/pCEP4 cells. The protective effect of increased Bcl-2 expression was manifested by a failure of ara-C to induce activation/cleavage of the Yama protease (CPP32; caspase-3) and degradation of one of its substrates, poly(ADP-ribose)polymerase to an 85-kDa cleavage product. When HL-60/Bcl-2 cells were preincubated with bryostatin 1 (10 nM; 24 hr) or coincubated with either staurosporine (50 nM; 6 hr) or UCN-01 (300 nM; 6 hr) after a 1-hr preincubation, exposures that exerted minimal effects alone, ara-C-induced apoptosis and DNA fragmentation were restored to levels equivalent to, or greater than, those observed in empty-vector controls. These events were accompanied by restoration of the ability of ara-C to induce CPP32 cleavage and activation, poly(ADP-ribose) polymerase degradation, and inhibition of colony formation. Western analysis of Bcl-2 protein obtained from overexpressing cells treated with bryostatin 1, staurosporine, or UCN-01 revealed the appearance of a slowly migrating species and a general broadening of the protein band, effects that were insensitive to the protein synthesis inhibitor cycloheximide. Alterations in Bcl-2 protein mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were reversed by treatment of lysates with alkaline phosphatase or protein phosphatase 2A; actions of the latter were blocked by the specific phosphatase inhibitor okadaic acid. In vivo labeling studies of Bcl-2 protein demonstrated increased incorporation of [32PO4]orthophosphate in drug-treated cells. Last, phosphorylated Bcl-2 failed to display decreased binding to the proapoptotic protein Bax. Collectively, these findings indicate that bryostatin 1, which down-regulates PKC, and staurosporine and UCN-01, which directly inhibit the enzyme, circumvent resistance of Bcl-2-overexpressing leukemic cells to ara-C-induced apoptosis and activation of the protease cascade. They also raise the possibility that modulation of Bcl-2 phosphorylation status contributes to this effect.
Mol Pharmacol 1997 Dec
PMID:Agents that down-regulate or inhibit protein kinase C circumvent resistance to 1-beta-D-arabinofuranosylcytosine-induced apoptosis in human leukemia cells that overexpress Bcl-2. 939 80

Programmed cell death (apoptosis) is a controlled process by which unwanted cells are selectively eliminated. Several families of proteins including the Bcl-2, tumor necrosis factor receptor 1, and caspase families play essential roles in the regulation, signaling, and execution of the genetic cell death program. The recently described three-dimensional structures of members of these families elucidate the structural basis of their functions and provide insights into the mechanisms by which these proteins regulate apoptosis.
J Mol Biol 1997 Dec 05
PMID:Three-dimensional structures of proteins involved in programmed cell death. 940 39

Recent evidence demonstrates that the proto-oncogene product, Bcl-2 can protect cells from a variety of cell death-inducing stimuli. Because previous studies have demonstrated that protein kinase (PK) pathways may be involved in the regulation of cell death, we tested various PK inhibitors for their effects on cell death in a dopaminergic neuronal cell line, MN9D, as well as the potential of Bcl-2 family members and structural mutants to block this process. Cells expressing either human Bcl-2 (MN9D/Bcl-2), or neomycin (MN9D/Neo; control cells) were treated with either staurosporine (0.25-2 microM) or trifluoperazine (10-100 microM). In control MN9D/Neo cells, both reagents led to a dose-dependent cell death with morphological features of apoptosis. Overexpression of Bcl-2 rescued cells from staurosporine-induced but not trifluoperazine-induced apoptotic cell death. Cell death induced by the specific PKC inhibitor, calphostin C was also significantly attenuated in MN9D/Bcl-2 cells indicating that a PKC pathway represents one mechanism by which Bcl-2 prevents staurosporine-induced cell death. Similarly, the Bcl-2 family member, Bcl-X(L) also blocked staurosporine-induced cell death in MN9D cells whereas overexpression of Bcl-X(S) or Bax did not. Finally, staurosporine-induced cell death was still blocked by the expression of clones encoding mutations in the Bcl-2 homology domains, BH1 and BH2, as well as C-terminally truncated Bcl-2. These data suggest that in the staurosporine-mediated cell death model Bcl-2 is not heterodimerizing to related proteins through these highly conserved structural domains nor does it need to be membrane-anchored. Thus, in this paradigm, either Bcl-2 functions as a homodimer or essential sequences lie outside of the BH1 or BH2 domains.
Brain Res Mol Brain Res 1997 Nov
PMID:Regions outside of the Bcl-2 homology domains, BH1 and BH2 protect a dopaminergic neuronal cell line from staurosporine-induced cell death. 942 15

Recent work identified an apoptotic program in gastrulation stage Xenopus embryos (Anderson, J.A., Lewellyn, A.L., Maller, J.L., 1997. Mol. Biol. Cell 8, 1195-1206; Stack, J.H., Newport, J.W., 1997. Development 124, 3185-3195). Here, we characterize in detail this maternal cell death program, which is set up at fertilization and abruptly activated at the onset of gastrulation, following DNA damage or treatment of embryos with inhibitors of transcription, translation, or replication, between the time of fertilization and the midblastula transition (MBT). This apoptotic pathway is activated under tightly regulated developmental control(s): if the same treatments are applied after the MBT the apoptotic response is abrogated. Embryos displayed many characteristic apoptotic features, including DNA fragmentation, caspase activation, and embryonic death was blocked in vivo by the ectopic expression of Bcl-2, or injection of the caspase-3 inhibitor z-DEVD-fmk. The precise timing and the execution of this maternal cell death program is set at fertilization and does not depend on the type of stress applied, on cell cycle progression, or on de novo protein synthesis. This maternal developmental program might palliate the lack of cell cycle checkpoints in the pre-MBT embryo.
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PMID:A developmental timer that regulates apoptosis at the onset of gastrulation. 948 40

Bcl-2 is an anti-apoptotic gene important in B cell development. In order to study how apoptosis regulates somatic hypermutation and selection of B cell clones in the germinal center, we examined the antibody response to phosphorylcholine (PC) in transgenic mice overexpressing bcl-2 in the B cell compartment. The anti-PC antibody response is dominated by the S107V1 variable region heavy chain gene. We, therefore, analyzed S107V1-encoded heavy chains from germinal center cells. The proportion of germinal center sequences that were mutated, and the frequency of mutations did not differ significantly between the two groups of mice. No significant differences were found in the clustering of replacement mutations in the complementarity determining regions (CDRs) and in replacement to silent (R:S) mutation ratios. A significant difference between bcl-2 transgenic mice and controls, however, was found in the targeting of mutations to oligonucleotide motifs presumed to be mutational "hot spots." While non-transgenic mice displayed the expected clustering of mutations in hot spots, mutations from bcl-2 transgenic mice lacked this pattern. This observation suggests that the mechanism for somatic hypermutation includes two distinct functions, a non-specific mutational apparatus and a mechanism to target mutation to hot spots, and that in certain circumstances these functions may be uncoupled.
Mol Immunol 1997 Oct
PMID:Overexpression of bcl-2 alters usage of mutational hot spots in germinal center B cells. 948 52

The expression of the Bcl-2 family proteins Bax, Mcl-1, Bcl-2, and Bcl-xL, was examined in human peripheral blood eosinophils or in umbilical-cord-blood-derived eosinophils. Immunoblot analysis disclosed high amounts of the proapoptotic factor Bax in freshly purified eosinophils of both types. Although cord-blood-derived eosinophils expressed easily detectable levels of Mcl-1, Bcl-2, and Bcl-xL, only traces or no expression of these three antiapoptotic proteins were found in peripheral blood eosinophils. Incubation of both eosinophil types for 1 to 3 days in a cytokine-deprived medium led to apoptosis, without changes in the expression of Bax, Mcl-1, Bcl-2, or Bcl-xL. Although addition of interleukin-5 or interferon-gamma (IFN-gamma) to the culture medium increased the survival of both eosinophil types, a rise in the levels of Mcl-1 was observed only in IFN-gamma-treated cord-blood eosinophils. Together, these results indicate that human eosinophils have a specific profile of Bcl-2-family protein expression that depends on their maturation status and may be modulated by stimuli that influence their survival.
Am J Respir Cell Mol Biol 1998 Mar
PMID:Human eosinophils express bcl-2 family proteins: modulation of Mcl-1 expression by IFN-gamma. 949 Jun 49

Myocyte apoptosis increases with age in Fischer 344 rats, but the multiple molecular events implicated in this phenomenon remain to be identified. Several defects involving Ca2+ homeostasis, pH, and the expression of p53 and genes of the Bcl-2 protein family may contribute to the activation of myocyte death. Therefore, changes in intracellular pH, cytosolic Ca2+, DNase I and DNase II were measured in myocytes isolated by enzymatic digestion from rats of different ages. Moreover, the expression of p53, Bcl-2 and Bax in these cells was determined. Measurements of intracellular pH by BCECF fluorescence at 3, 12 and 24 months showed that this parameter did not change with age: 3 months, 7.20+/-0.05; 12 months, 7.21+/-0.07; 24 months, 7.18+/-0.09. In contrast, diastolic Ca2+ determined by the Fura 2-AM method increased progressively from 99.8+/-1.9 nm at 3 months to 136.3+/-9.6 nm at 24 months (P<0.001). Concurrently, DNase I activity evaluated by plasmid digestion assay in myocytes increased 3.2-fold from 3 to 24 months (P<0.02). Conversely, pH-dependent-DNase II remained essentially constant with age. Western blotting performed on ventricular myocytes did not detect significant changes in p53, Bax and Bcl-2 proteins with age. Similarly, immunocytochemically, the fraction of myocytes labeled by p53, Bax and Bcl-2 did not change from 3 to 24 months. In conclusion, myocyte aging is characterized by an increase in diastolic calcium which may activate DNase I triggering apoptosis, independently from the expression of p53, Bax and Bcl-2 in the cells.
J Mol Cell Cardiol 1998 Mar
PMID:Intracellular calcium, DNase activity and myocyte apoptosis in aging Fischer 344 rats. 951 29

Phosphatidylinositol (PI) 3-kinase has been suggested to mediate cell survival. Consistent with this possibility, apoptosis of conditionally (simian virus 40 Tts) immortalized rat hippocampal H19-7 neuronal cells was increased in response to wortmannin, an inhibitor of PI 3-kinase. Downstream effectors of PI 3-kinase include Rac1, protein kinase C, and the serine-threonine kinase Akt (protein kinase B). Here, we show that activation of Akt is one mechanism by which PI 3-kinase can mediate survival of H19-7 cells during serum deprivation or differentiation. While ectopic expression of wild-type Akt (c-Akt) does not significantly enhance survival in H19-7 cells, expression of activated forms of Akt (v-Akt or myristoylated Akt) results in enhanced survival which can be comparable to that conferred by Bcl-2. Conversely, expression of a dominant-negative mutant of Akt accelerates cell death upon serum deprivation or differentiation. Finally, the results indicate that Akt can transduce a survival signal for differentiating neuronal cells through a mechanism that is independent of induction of Bcl-2 or Bcl-XL or inhibition of Jun kinase activity.
Mol Cell Biol 1998 Apr
PMID:Akt, a target of phosphatidylinositol 3-kinase, inhibits apoptosis in a differentiating neuronal cell line. 952 86


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