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)

Approximately half of the neurons produced during embryogenesis normally die before adulthood. Although target-derived neurotrophic factors are known to be major determinants of programmed cell death--apoptosis--the molecular mechanisms by which trophic factors interfere with cell death regulation are largely unknown. Overexpression of the bcl-2 proto-oncogene in cultured sympathetic neurons has now been shown to prevent apoptosis normally induced by deprivation of nerve growth factor. This finding, together with the previous demonstration of bcl-2 expression in the nervous system, suggests that the Bcl-2 protein may be a major mediator of the effects of neurotrophic factors on neuronal survival.
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PMID:Prevention of programmed cell death of sympathetic neurons by the bcl-2 proto-oncogene. 141 28

The bcl2 protooncogene was originally discovered because of its involvement in t(14;18) chromosomal translocations frequently found in non-Hodgkin's lymphomas. The expression of this gene is reported to be highly tissue specific, with bcl2 mRNAs being readily detectable only in hematolymphoid tissues and brain. To explore the possible involvement of bcl2 in neural tumors, we surveyed a variety of tumor cell lines for the presence of the p26-BCL2 protein by immunoprecipitation and immunoblotting methods. Very high levels of BCL2 protein were found in three of nine neuroblastoma (NB) cell lines examined; these levels of p26-BCL2 were comparable to lymphoma cell lines that contain a t(14;18). Despite the impressive relative amounts of BCL2 protein, however, no structural alterations or changes in the methylation status of bcl2 genes were detected in these NB cell lines by conventional Southern blotting. Of the other NB cell lines surveyed, three contained intermediate levels of BCL2 and another three cell lines had little or no detectable BCL2 protein, raising the possibility that determination of relative levels of BCL2 protein may help to segregate neuroblastomas into groups with different biological and clinical characteristics. BCL2 protein levels were not influenced by induction of neuronal differentiation with nerve growth factor in two of the two cell lines examined [SH-SY5Y (high BCL2); GICAN (low BCL2)] and did not correlate with N-MYC gene amplification or expression of nerve growth factor receptors. NB cell lines that contained little or no detectable BCL2 protein, however, tended to contain significant proportions of flat epithelioid cells, whereas bcl2-expressing cell lines were composed primarily of neuronal-like cells, suggesting that expression of this protooncogene correlates with the differentiation characteristics of these tumor cell lines. In addition to NBs, lower levels of BCL2 protein were also found in a variety of other neural crest-derived tumors and tumor cell lines, including some neuroepitheliomas, Ewing's sarcomas, neurofibromas, and melanomas. With regard to tumors of central nervous system origin, bcl2 expression was absent from most medulloblastomas but was detected at moderate to low levels in a retinoblastoma and some glioblastoma multiforme cell lines. Taken together, these findings imply that bcl2 protooncogene expression is differentially regulated within the various lineages of cells that give rise to the nervous system.
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PMID:Differential expression of bcl2 protooncogene in neuroblastoma and other human tumor cell lines of neural origin. 174 26

Selective induction of programmed cell death, apoptosis, may represent a new approach to the treatment of cancer. Apoptosis can be induced by the monoclonal antibody anti-APO-1 directed against the cell surface receptor APO-1, a member of the nerve growth factor (NGF) receptor/tumor necrosis factor (TNF) receptor superfamily. We determined APO-1 expression and sensitivity to anti-APO-1 mediated apoptosis in childhood acute lymphoblastic leukemia cells of T lymphocyte precursor phenotype (T-ALL). APO-1 was constitutively expressed by 21 of 30 T-ALL and by all T-ALL cell lines investigated. However, most APO-1 positive T-ALL were resistant to anti-APO-1 mediated apoptosis. Sensitivity to anti-APO-1 mediated apoptosis was independent of the density of APO-1 expression on the cell surface and independent of the amount of Bcl-2. Incubation of resistant T-ALL with the protein synthesis inhibitor cycloheximide reversed resistance and induced sensitivity to anti-APO-1 mediated apoptosis in most T-ALL. These data suggest that resistance to anti-APO-1 mediated apoptosis in T-ALL is maintained by an active cellular program. Reversion of resistance to sensitivity towards induction of apoptosis in tumors may provide a new basis for successful therapeutic intervention.
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PMID:Resistance to APO-1 (CD95) induced apoptosis in T-ALL is determined by a BCL-2 independent anti-apoptotic program. 753 14

Developing neurons die if they fail to obtain an adequate supply of neurotrophins from their targets but how neurotrophins suppress cell death is not known. Although over-expression of exogenous Bcl-2 can prevent the death of cultured neurons deprived of members of the nerve growth factor family of neurotrophins it is not known if this effect is physiologically relevant. To determine if Bcl-2 participates in the neurotrophin survival response we used antisense bcl-2 RNA to inhibit endogenous Bcl-2 expression. Here we show that brain-derived neurotrophic factor (BDNF)-dependent neurons are killed by antisense bcl-2 RNA in the presence of BDNF. However, when these neurons were supported with ciliary neurotrophic factor (CNTF) their survival was not affected by antisense bcl-2 RNA. Likewise, the survival of CNTF-dependent ciliary neurons was not affected by antisense bcl-2 RNA. Our findings suggest that Bcl-2 is required for the BDNF survival response and that alternative, Bcl-2-independent survival mechanisms operate in sensory and parasympathetic neurons exposed to CNTF.
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PMID:Role of Bcl-2 in the brain-derived neurotrophic factor survival response. 758 99

A number of DNA viruses carry apoptosis-inhibiting genes which enable the virus to escape from the host response. The adenovirus E1B 19K protein can inhibit apoptosis induced by E1A, tumour-necrosis factor-alpha, FAS antigen and nerve growth factor deprivation. The molecular basis of this inhibition remains poorly understood, but the fact that protection is seen in the absence of other viral proteins suggests that E1B 19K targets cellular proteins. We report here the identification of three cellular proteins that bind E1B 19K. One of these is a new member of the bcl-2 family, which we have called bak (for bcl-2 homologous antagonist/killer). This protein, which is expressed in a wide variety of cell types, binds to E1B 19K and to the Bcl-2 homologue Bcl-XL (ref. 17) in yeast. In addition, overexpression of bak in sympathetic neurons deprived of nerve growth factor accelerates apoptosis and blocks the protective effect of co-injected E1B 19K.
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PMID:Cloning of a bcl-2 homologue by interaction with adenovirus E1B 19K. 771 29

Previous studies have implicated the bcl-2 protooncogene as a potential regulator of neuronal survival. However, mice lacking functional bcl-2 exhibited normal development and maintenance of the central nervous system (CNS). Since bcl-2 appears dispensable for neuronal survival, we have examined the expression and function of bcl-x, another member of the bcl-2 family of death regulatory genes. Bcl-2 is expressed in neuronal tissues during embryonic development but is down-regulated in the adult CNS. In contrast, Bcl-xL expression is retained in neurons of the adult CNS. Two different forms of bcl-x mRNA and their corresponding products, Bcl-xL and Bcl-x beta, were expressed in embryonic and adult neurons of the CNS. Microinjection of bcl-xL and bcl-x beta cDNAs into primary sympathetic neurons inhibited their death induced by nerve growth factor withdrawal. Thus, Bcl-x proteins appear to play an important role in the regulation of neuronal survival in the adult CNS.
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PMID:bcl-x is expressed in embryonic and postnatal neural tissues and functions to prevent neuronal cell death. 775 2

The bcl-2 protooncogene, which protects various cell types from apoptotic cell death, is expressed in the developing and adult nervous system. To explore its role in regulation of neuronal cell death, we generated transgenic mice expressing Bcl-2 under the control of the neuron-specific enolase promoter, which forced expression uniquely in neurons. Sensory neurons isolated from dorsal root ganglia of newborn mice normally require nerve growth factor for their survival in culture, but those from the bcl-2 transgenic mice showed enhanced survival in its absence. Furthermore, apoptotic death of motor neurons after axotomy of the sciatic nerve was inhibited in these mice. The number of neurons in two neuronal populations from the central and peripheral nervous system was increased by 30%, indicating that Bcl-2 expression can protect neurons from cell death during development. The generation of these transgenic mice suggests that Bcl-2 may play an important role in survival of neurons both during development and throughout adult life.
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PMID:bcl-2 transgene expression can protect neurons against developmental and induced cell death. 775 17

To study molecular mechanisms underlying neuronal cell death, we have used sympathetic neurons from superior cervical ganglia which undergo programmed cell death when deprived of nerve growth factor. These neurons have been microinjected with expression vectors containing cDNAs encoding selected proteins to test their regulatory influence over cell death. Using this procedure, we have shown previously that sympathetic neurons can be protected from NGF deprivation by the protooncogene Bcl-2. We now report that the E1B19K protein from adenovirus and the p35 protein from baculovirus also rescue neurons. Other adenoviral proteins, E1A and E1B55K, have no effect on neuronal survival. E1B55K, known to block apoptosis mediated by p53 in proliferative cells, failed to rescue sympathetic neurons suggesting that p53 is not involved in neuronal death induced by NGF deprivation. E1B19K and p35 were also coinjected with Bcl-Xs which blocks Bcl-2 function in lymphoid cells. Although Bcl-Xs blocked the ability of Bcl-2 to rescue neurons, it had no effect on survival that was dependent upon expression of E1B19K or p35.
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PMID:Viral proteins E1B19K and p35 protect sympathetic neurons from cell death induced by NGF deprivation. 782 15

Bcl-2 is a mitochondrial- and perinuclear-associated protein that prolongs the lifespan of a variety of cell types by interfering with programmed cell death (apoptosis). Bcl-2 seems to function in an antioxidant pathway, and it is believed that membrane attachment mediated by a COOH-terminal hydrophobic tail is required for its full activity. To identify critical regions in bcl-2 alpha for subcellular localization, activity, and/or interaction with other proteins, we created, by site-directed mutagenesis, various deletion, truncation, and point mutations. We show here that membrane attachment is not required for the survival activity of bcl-2 alpha. A truncation mutant of bcl-2 alpha lacking the last 33 amino acids (T3.1) including the hydrophobic COOH terminus shows full activity in blocking apoptosis of nerve growth factor-deprived sympathetic neurons or TNF-alpha-treated L929 fibroblasts. Confocal microscopy reveals that the T3 mutant departs into the extremities of neurites in neurons and filopodias in fibroblasts. Consistently, T3 is predominantly detected in the soluble fraction by Western blotting, and is not inserted into microsomes after in vitro transcription/translation. We further provide evidence for motifs (S-N and S-II) at the NH2 and COOH terminus of bcl-2, which are crucial for its activity.
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PMID:The protein bcl-2 alpha does not require membrane attachment, but two conserved domains to suppress apoptosis. 805 Dec 5

Production of nerve growth factor (NGF) was assessed in cultures of human T and B lymphocytes and macrophages. NGF was constitutively produced by B cells only, which also expressed surface p140trk-A and p75NGFR molecules and hence efficiently bound and internalized the cytokine. Neutralization of endogenous NGF caused disappearance of Bcl-2 protein and apoptotic death of resting lymphocytes bearing surface IgG or IgA, a population comprising memory cells, while surface IgM/IgD "virgin" B lymphocytes were not affected. In vivo administration of neutralizing anti-NGF antibodies caused strong reduction in the titer of specific IgG in mice immunized with tetanus toxoid, nitrophenol, or arsonate and reduced numbers of surface IgG or IgA B lymphocytes. Thus, NGF is an autocrine survival factor for memory B lymphocytes.
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PMID:Nerve growth factor is an autocrine survival factor for memory B lymphocytes. 861 90


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