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 pathway to cell death in Caenorhabditis elegans is well established. In cells undergoing apoptosis, the Bcl-2 homology domain 3 (BH3)-only protein EGL-1 binds to CED-9 at the mitochondrial membrane to cause the release of CED-4, which oligomerises and facilitates the activation of the caspase CED-3. However, despite many studies, the biophysical features of the CED-4/CED-9 complex have not been fully characterised. Here, we report the purification of a soluble and stable 2 : 2 heterotetrameric complex formed by recombinant CED-4 and CED-9 coexpressed in bacteria. Consistent with previous studies, synthetic peptides corresponding to the BH3 domains of worm BH3-only proteins (EGL-1, CED-13) dissociate CED-4 from CED-9, but not from the gain-of-function CED-9 (G169E) mutant. Surprisingly, the ability of worm BH3 domains to dissociate CED-4 was specific since mammalian BH3-only proteins could not do so.
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PMID:CED-4 forms a 2 : 2 heterotetrameric complex with CED-9 until specifically displaced by EGL-1 or CED-13. 1616 70

Bcl-2 family proteins include anti- and proapoptotic factors that play important roles in regulating apoptosis in diverse species. Identification of compounds that can modulate the activities of Bcl-2 family proteins will facilitate development of drugs for treatment of apoptosis-related human diseases. We used an in vitro selection method named systematic evolution of ligands by exponential enrichment (SELEX) to isolate RNA aptamers that bind the Caenorhabditis elegans Bcl-2 homolog CED-9 with high affinity and specificity and tested whether these aptamers modulate programmed cell death in C. elegans. Five CED-9 aptamers were isolated and classified into three groups based on their predicted secondary structures. Biochemical analyses indicated that two of these aptamers, R9-2 and R9-7, and EGL-1, an endogenous CED-9-binding proapoptotic protein, bound to distinct regions of CED-9. However, these two aptamers shared overlapping CED-9 binding sites with CED-4, another CED-9-binding proapoptotic factor. Importantly ectopic expression of these two aptamers in touch receptor neurons induced efficient killing of these neurons largely in a CED-3 caspase-dependent manner. These findings suggest that RNA aptamers can be used to modulate programmed cell death in vivo and can potentially be used to develop drugs to treat human diseases caused by abnormal apoptosis.
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PMID:RNA aptamers targeting the cell death inhibitor CED-9 induce cell killing in Caenorhabditis elegans. 1646 3

Bcl-2 family proteins play central roles in apoptosis by regulating the release of mitochondrial intermembrane space proteins such as cytochrome c. Death-promoting Bcl-2 family members, such as Bax, can promote cytochrome c release and fragmentation of the mitochondrial network, whereas apoptosis-inhibitory members, such as Bcl-2 and Bcl-xL, can antagonize these events. It remains unclear whether CED-9, the worm Bcl-2 relative, can regulate mitochondrial fission/fusion dynamics or the release of proteins from the mitochondrial intermembrane space. Here, we show that CED-9 interacts with Mitofusin-2/fuzzy onions and can promote mitochondrial clustering and dramatic reorganization of mitochondrial networks. Consistent with its ability to neutralize CED-9 function, EGL-1 antagonized CED-9-dependent remodeling of the mitochondrial network. However, CED-9 failed to inhibit mitochondrial cytochrome c release or apoptosis induced by diverse triggers in mammalian cells. These data suggest that the ability to regulate mitochondrial fission/fusion dynamics is an evolutionarily conserved property of the Bcl-2 family.
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PMID:Role for CED-9 and Egl-1 as regulators of mitochondrial fission and fusion dynamics. 1654 41

A novel transferrin receptor (TfR)-targeted liposomal formulation was synthesized and evaluated for the delivery of a phosphorothioate antisense oligodeoxyribonucleotide (ODN) (G3139, oblimerson sodium, or Genasense) to Bcl-2 in K562 leukemia cells. Liposomes composed of DC-Chol/egg PC/PEG-DSPE (25:73.5:1.5, mol/mol/mol) were loaded with G3139 with high efficiency (70-80%). To prepare targeted liposomes, transferrin was first coupled to PEG-DSPE and then incorporated into the bilayer by post-insertion. The liposomes had a mean diameter of 100 to 150 nm and exhibited colloidal stability for up to 8 weeks. Uptake of Tf-conjugated G3139-containing liposomes in TfR positive K562 cells was found to be more efficient than that of the non-targeted control formulation and could be blocked by excess free Tf. Treatment with Tf-conjugated liposomes resulted in Bcl-2 protein downregulation in K562 cells that was approximately 2-fold greater than with non-targeted liposomes (p<0.05) and 10-fold greater than with free G3139. Treatment with 2 microM G3139 in Tf-conjugated liposomes resulted in >80% reduction in Bcl-2 transcript. In addition, Tf-conjugated liposomal G3139-sensitized K562 cells to daunorubicin, lowering IC50 from 1.8 microM to 0.18 microM. In conclusion, Tf-conjugated liposomes are effective delivery vehicles for G3139 antisense oligos in TfR positive K562 cells and warrant further investigation as an in vivo oligo delivery vehicle.
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PMID:Efficient delivery of a Bcl-2-specific antisense oligodeoxyribonucleotide (G3139) via transferrin receptor-targeted liposomes. 1656 96

Although the anti-apoptotic activity of Bcl-2 has been extensively studied, its mode of action is still incompletely understood. In the nematode Caenorhabditis elegans, 131 of 1090 somatic cells undergo programmed cell death during development. Transgenic expression of human Bcl-2 reduced cell death during nematode development, and partially complemented mutation of ced-9, indicating that Bcl-2 can functionally interact with the nematode cell death machinery. Identification of the nematode target(s) of Bcl-2 inhibition would help clarify the mechanism by which Bcl-2 suppresses apoptosis in mammalian cells. Exploiting yeast-based systems and biochemical assays, we analysed the ability of Bcl-2 to interact with and regulate the activity of nematode apoptosis proteins. Unlike CED-9, Bcl-2 could not directly associate with the caspase-activating adaptor protein CED-4, nor could it inhibit CED-4-dependent yeast death. By contrast, Bcl-2 could bind the C. elegans pro-apoptotic BH3-only Bcl-2 family member EGL-1. These data prompt us to hypothesise that Bcl-2 might suppress nematode cell death by preventing EGL-1 from antagonising CED-9, rather than by inhibiting CED-4.
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PMID:Human Bcl-2 cannot directly inhibit the Caenorhabditis elegans Apaf-1 homologue CED-4, but can interact with EGL-1. 1673 40

Temporal control of programmed cell death is necessary to ensure that cells die at only the right time during animal development. How such temporal regulation is achieved remains poorly understood. In some Caenorhabditis elegans somatic cells, transcription of the egl-1/BH3-only gene promotes cell-specific death. The EGL-1 protein inhibits the CED-9/Bcl-2 protein, resulting in the release of the caspase activator CED-4/Apaf-1. Subsequent activation of the CED-3 caspase by CED-4 leads to cell death. Despite the important role of egl-1 transcription in promoting CED-3 activity in cells destined to die, it remains unclear whether the temporal control of cell death is mediated by egl-1 expression. Here, we show that egl-1 and ced-9 play only minor roles in the death of the C. elegans tail-spike cell, demonstrating that temporal control of tail-spike cell death can be achieved in the absence of egl-1. We go on to show that the timing of the onset of tail-spike cell death is controlled by transcriptional induction of the ced-3 caspase. We characterized the developmental expression pattern of ced-3, and show that, in the tail-spike cell, ced-3 expression is induced shortly before the cell dies, and this induction is sufficient to promote the demise of the cell. Both ced-3 expression and cell death are dependent on the transcription factor PAL-1, the C. elegans homolog of the mammalian tumor suppressor gene Cdx2. PAL-1 can bind to the ced-3 promoter sites that are crucial for tail-spike cell death, suggesting that it promotes cell death by directly activating ced-3 transcription. Our results highlight a role that has not been described previously for the transcriptional regulation of caspases in controlling the timing of cell death onset during animal development.
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PMID:Timing of the onset of a developmental cell death is controlled by transcriptional induction of the C. elegans ced-3 caspase-encoding gene. 1732 62

In order to overcome the problems of enzymatic degradation and short plasma half life, which can limit the delivery of antisense oligonucleotides, and the potential immuno-stimulatory effects of CpG motifs, we utilized a polyethylene glycol (PEG) technology that employed various releasable linkers (rPEG). 5'-20 kDa-PEGylation of an anti-Bcl-2 5'-aminoalkyl-oligonucleotide with the same sequence as G3139 (Compound 1) did not alter its binding to the heparin-binding protein bFGF, nor the release of cytochrome c from isolated mitochondria treated with the conjugates. However, in 518A2 melanoma cells in vitro, PEGylation resulted in greatly diminished cellular uptake. In striking contrast, PEGylation of 1 resulted in dramatically improved pharmacokinetic profiles in vivo, with a prolonged half-life (t1/2), increased plasma concentration, and increased area under the plasma concentration-time curve (AUC). In an in vivo melanoma 518A2 xenograft mouse model, treatment with either 5'-20 kDa-PEG-1 or 1 demonstrated similar tumor growth inhibition. Furthermore, in an in vitro mouse splenocyte culture system, attachment of a PEG moiety to 1 through releasable linkers abolished the immunostimulatory response that was observed for G3139. Our results demonstrate the potential of the in vivo use of PEGylated oligonucleotides, and point out the profound differences between in vitro and in vivo models of oligonucleotide activity.
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PMID:Delivery of G3139 using releasable PEG-linkers: impact on pharmacokinetic profile and anti-tumor efficacy. 1739 60

The anti-apoptotic proteins Bcl-2 and Bcl-X(L) bind and inhibit Beclin-1, an essential mediator of autophagy. Here, we demonstrate that this interaction involves a BH3 domain within Beclin-1 (residues 114-123). The physical interaction between Beclin-1 and Bcl-X(L) is lost when the BH3 domain of Beclin-1 or the BH3 receptor domain of Bcl-X(L) is mutated. Mutation of the BH3 domain of Beclin-1 or of the BH3 receptor domain of Bcl-X(L) abolishes the Bcl-X(L)-mediated inhibition of autophagy triggered by Beclin-1. The pharmacological BH3 mimetic ABT737 competitively inhibits the interaction between Beclin-1 and Bcl-2/Bcl-X(L), antagonizes autophagy inhibition by Bcl-2/Bcl-X(L) and hence stimulates autophagy. Knockout or knockdown of the BH3-only protein Bad reduces starvation-induced autophagy, whereas Bad overexpression induces autophagy in human cells. Gain-of-function mutation of the sole BH3-only protein from Caenorhabditis elegans, EGL-1, induces autophagy, while deletion of EGL-1 compromises starvation-induced autophagy. These results reveal a novel autophagy-stimulatory function of BH3-only proteins beyond their established role as apoptosis inducers. BH3-only proteins and pharmacological BH3 mimetics induce autophagy by competitively disrupting the interaction between Beclin-1 and Bcl-2 or Bcl-X(L).
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PMID:Functional and physical interaction between Bcl-X(L) and a BH3-like domain in Beclin-1. 1743 66

Terminal prostate cancer is refractory to conventional anticancer treatments because of frequent overexpression of antiapoptotic proteins Bcl-2 and/or Bcl-x(L). Adenovirus-mediated delivery of melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24), a secreted cytokine having cancer-selective apoptosis-inducing properties, profoundly inhibits prostate cancer cell growth. However, forced overexpression of Bcl-2 or Bcl-x(L) renders prostate cancer cells resistant to Ad.mda-7. We constructed a conditionally replication-competent adenovirus in which expression of the adenoviral E1A gene, necessary for replication, is driven by the cancer-specific promoter of progression elevated gene-3 (PEG-3) and which simultaneously expresses mda-7/IL-24 in the E3 region of the adenovirus (Ad.PEG-E1A-mda-7), a cancer terminator virus (CTV). This CTV generates large quantities of MDA-7/IL-24 as a function of adenovirus replication uniquely in cancer cells. Infection of Ad.PEG-E1A-mda-7 (CTV) in normal prostate epithelial cells and parental and Bcl-2- or Bcl-x(L)-overexpressing prostate cancer cells confirmed cancer cell-selective adenoviral replication, mda-7/IL-24 expression, growth inhibition, and apoptosis induction. Injecting Ad.PEG-E1A-mda-7 (CTV) into xenografts derived from DU-145-Bcl-x(L) cells in athymic nude mice completely eradicated not only primary tumors but also distant tumors (established in the opposite flank), thereby implementing a cure. These provocative findings advocate potential therapeutic applications of this novel virus for advanced prostate cancer patients with metastatic disease.
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PMID:Eradication of therapy-resistant human prostate tumors using a cancer terminator virus. 1754 25

Transient focal ischemia caused by middle cerebral artery occlusion (MCAo) produces apoptotic cell death in the penumbra area. Bcl-2 is a protooncogene that plays a major antiapoptotic role, at the cellular level, by counteracting the activation of apoptosis effectors, that is, caspases. It has been suggested that nitroglycerin (NTG), a nitric oxide donor, reduces ischemia/reperfusion-induced brain damage via the inhibition of caspase activity and NMDA receptor. In this chapter, we evaluated the protective effects of NTG against cerebral damage caused by transient (2h) MCAo (tMCAo) focusing our interest on the potential effects on Bcl-2 expression. Male Wistar rats were administered intraperitoneally (i.p.) with NTG (10mg/kg) or vehicle (PEG, 1ml/kg) 20min before the induction of MCAo by intraluminal silicon-coated filament (0.37-mm diameter). Cerebral infarct volume was measured 22h after reperfusion, while cortical Bcl-2 expression was evaluated at the end of 2-h MCAo (without reperfusion) and at 5h of reperfusion. The results show significant reduction of the infarct volume in rats preinjected with NTG, as compared to the vehicle group. After 2h of occlusion, no significant difference was seen in Bcl-2 expression in the ipsilateral and contralateral cortex of either experimental groups (NTG and vehicle). However, 5h after reperfusion, a significant increase of Bcl-2 expression was detected in the damaged cortex of control rats, probably reflecting a compensatory response aiming at counteracting the cell death process; this increase was absent in the NTG-treated rats. These data, while confirming the neuroprotective effect of NTG in an in vivo ischemia/reperfusion model, seem to suggest that the drug may act by downsizing the complex chain of events underlying apoptosis activation and consequent activation of antiapoptotic responses.
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PMID:Neuroprotective effect of nitroglycerin in a rodent model of ischemic stroke: evaluation of Bcl-2 expression. 1767 76


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