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)

A substantial body of data from clinical and laboratory studies indicates that reactive oxygen intermediates are implicated in the pathogenesis of diverse human diseases, including cancer, diabetes, and neurodegenerative disorders. Oxidative stress induced by reactive oxygen intermediates often causes cell death via apoptosis that is regulated by a plenty of functional genes and their protein products. Bcl-2, which is an integral intermitochondrial membrane protein, blocks apoptosis induced by a wide array of death signals. In spite of extensive research, the molecular milieu that characterizes the antiapoptotic function of Bcl-2 is complex and not fully identified. Recently, there are several lines of evidence that Bcl-2 functions via antioxidant pathways to prevent apoptosis. Thus, bcl-2-overexpressing cells exhibit elevated expression of antioxidant enzymes and higher levels of cellular GSH compared with the control cells transfected with the vector alone. There has been increasing evidence supporting that the redox-sensitive transcription factor nuclear factor kappaB regulates the activity and/or expression of antioxidative and antiapoptotic target genes and promotes cell survival against oxidative cell death. This commentary focuses on the antioxidative functions of Bcl-2 and underlying molecular mechanisms in relation to its antiapoptotic property. The role of Bcl-2 in regulation of nuclear factor kappaB signaling pathways and possible cross-talk with mitogen-activated protein kinases are also discussed.
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PMID:Potentiation of cellular antioxidant capacity by Bcl-2: implications for its antiapoptotic function. 1455 11

Bax is a pro-apoptotic member of the Bcl-2 family of proteins, which is present in the cytosol of various types of cells in full-length form (p21 Bax). During apoptosis, the N-terminal truncated version of Bax (p18 Bax) is often formed via cleavage of the p21 Bax by the calcium-dependent enzyme, calpain. p18 Bax is a membrane protein found primarily in the mitochondrial fraction of apoptotic cells. Although noticeable amounts of p18 Bax appear relatively late in apoptosis, it may still play a role in the apoptotic cascade. The role of p18 Bax in the apoptotic cascade, particularly, in the release of cytochrome c from mitochondria has not been studied. The goal of this study was to produce reasonable amounts of p18 Bax and study its effect on isolated mitochondria. The expression and purification of membrane proteins such as p18 Bax represents a substantial challenge due to insolubility. We report here that the apoptotic form of Bax, p18 Bax, is highly soluble in the absence of detergents upon fusion with maltose-binding protein (MBP). We describe a scheme for expression and simple metal-affinity based purification of MBP-p18Bax. The MBP-p18Bax triggers the release of cytochrome c from isolated mitochondria in a concentration-dependent, Bcl-2-sensitive manner. The MBP tag of the MBP-p18Bax can be cleaved off with 3C protease to produce pure p18 Bax, although the solubility of p18 Bax becomes very limited. The highly soluble, MBP-fused form of p18 Bax provides a convenient tool to study this apoptotic form of Bax protein.
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PMID:High-yield expression and purification of p18 form of Bax as an MBP-fusion protein. 1513 94

Apoptosis plays a critical role in many neurologic diseases, including stroke. Cytochrome c release and activation of various caspases are known to occur after focal and global ischemia. However, recent reports indicate that caspase-independent pathways may also be involved in ischemic damage. Apoptosis-inducing factor (AIF) is a novel flavoprotein that helps mediate caspase-independent apoptotic cell death. AIF translocates from mitochondria to nuclei where it induces caspase-independent DNA fragmentation. Bcl-2, a mitochondrial membrane protein, protects against apoptotic and necrotic death induced by different insults, including cerebral ischemia. In the present study, Western blots confirmed that AIF was normally confined to mitochondria but translocated to nuclei or cytosol 8, 24, and 48 hours after onset of ischemia. Overall, AIF protein levels also increased after stroke. Confocal microscopy further demonstrated that nuclear AIF translocation occurred in the peri-infarct region but not in the ischemic core where only some cytosolic AIF release was observed. Our data also suggest that AIF translocated into nuclei after cytochrome c was released into the cytosol. Bcl-2 transfection in the peri-infarct region blocked nuclear AIF translocation and improved cortical neuron survival.
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PMID:Bcl-2 transfection via herpes simplex virus blocks apoptosis-inducing factor translocation after focal ischemia in the rat. 1518 76

To investigate the possible mechanisms of nitric oxide (NO)-induced apoptosis in leukemia cell line HL-60, HL-60 cells in vitro were incubated with sodium nitroprusside (SNP), the in situ cell apoptosis quantitatively was assayed by TdT-mediated dUTP nick end labeling (TUNEL), the cell cycle DNA and proteins expression of Bcl-2, Bax, mitochondrial membrane protein (APO2.7) were analyzed by flow cytometry. The results showed that SNP induced HL-60 cell apoptosis in a dosage- and time-dependent manner. After exposure to SNP at the concentration of 1.0 mmol/L for 48 hours, the percentage of apoptosis HL-60 was (42.2 +/- 3.5)% for subG1 and (52.5 +/- 7.6)% for TUNEL respectively, and they are significantly higher than those in control and potassium ferricyanide (PFC) groups as same concentration. During the apoptosis process, it showed a decrease of Bcl-2 protein and an increase of Bax protein and mitochondrial membrane protein in HL-60 cell, proteins of Bcl-2, Bax and mitochondrial membrane were expressed in a dosage- and time-dependent manner too. In conclusion, during the process of SNP induced apoptosis in HL-60 cell, the expression of mitochondrial membrane protein was increased, Bcl-2 and Bax proteins may be important regulators.
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PMID:[Change of Bcl-2, Bax proteins and mitochondrial membrane protein on nitric oxide induced apoptosis in HL-60 cells]. 1536 28

Previous studies have shown that cerebral hypoxia results in increased tyrosine phosphorylation of cerebral cortical cell membrane proteins as well as nuclear membrane anti-apoptotic protein, Bcl-2. The present study tests the hypothesis that hypoxia results in increased protein tyrosine kinase activity in cortical cell membranes of newborn piglets and that the inhibition of neuronal NOS by administration of 7-nitroindazole sodium salt (7-NINA), a selective inhibitor of nitric oxide synthase (NOS), will prevent the hypoxia-induced increase in protein tyrosine kinase activity. To test this hypothesis, protein tyrosine kinase activity was determined in cerebral cortical membranes of 2- to 4-day-old newborn piglets divided into normoxic (n=6), hypoxic (n=5) and 7-NINA-treated hypoxic (n=5) (7-NINA, 1mg/kg, i.p., prior to hypoxia) groups. Tissue hypoxia was achieved by exposing the animals to an FiO(2) of 0.07 for 60 min and was documented biochemically by determining tissue ATP and phosphocreatine (PCr) levels. Cortical P(2) membranes were isolated and protein tyrosine kinase activity determined by (33)P incorporation into a specific peptide substrate for 15 min at 37 degrees C in a medium containing 100 mM HEPES, pH 7.0, 1mM EDTA, 125 mM MgCl(2), 25 mM MnCl(2), 2mM DTT, 0.2 mM sodium orthovanadate, 2mM EGTA, 150 microM tyrosine kinase peptide substrate [Lys 19] cdc2(6-20)-NH(2), (33)P-ATP, and 10 microg of membrane protein. Protein tyrosine kinase activity was determined by the difference between (33)P incorporation in the presence and absence of specific peptide substrate and expressed as pmol/mg protein/h. The ATP values in the normoxic, hypoxic and 7-NINA-treated hypoxic animals were ATP: 4.57+/-0.45 micromol/g, 1.29+/-0.23 micromol/g (p<0.05 versus normoxic) and 1.50+/-0.14 micromol/g brain (p<0.05 versus normoxic), respectively. The PCr values in the normoxic, hypoxic and 7-NINA-treated hypoxic animals were: 3.77+/-0.36 micromol/g, 0.77+/-0.13 micromol/g (p<0.05 versus normoxic) and 1.02+/-0.24 micromol/g brain (p<0.05 versus normoxic), respectively. Protein tyrosine kinase activity in the normoxic, hypoxic and the 7-NINA-treated groups was 378+/-77 pmol/mg protein/h, 854+/-169 pmol/mg protein/h (p<0.05 versus normoxic) and 464+/-129 pmol/mg protein/h (p<0.05 versus hypoxic), respectively. The data show that cerebral tissue hypoxia results in increased protein tyrosin kinase activity in cortical membranes of newborn piglets and pretreatment with 7-NINA prevents the hypoxia-induced increase in protein tyrosine kinase activity. We conclude that the hypoxia-induced increase in protein tyrosine kinase activity is NO-mediated. We propose that the hypoxia-induced increase in protein tyrosine kinase activity leading to increased phosphorylation of Bcl-2 is a critical link to hypoxic neuronal injury pathway.
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PMID:Effect of hypoxia on protein tyrosine kinase activity in cortical membranes of newborn piglets--the role of nitric oxide. 1553 Oct 99

Photodynamic therapy (PDT) is a novel cancer therapy inducing irreversible photodamage to tumor tissue via photosensitizer-mediated oxidative cytotoxicity. The cellular and molecular responses associated with PDT are only partially understood. We have reported previously the generation of several photosensitizer-specific PDT-resistant cell variants of HT29 human colon adenocarcinoma cells by selecting cells from sequential PDT treatment using different photosensitizers. In this report, we describe the use of messenger RNA (mRNA) differential display to identify genes that were differentially expressed in the parental HT29 cells compared with their resistant variants. In comparison with parental HT29 cells, mRNA expression was increased in the PDT-resistant cell variants for BNIP3, estrogen receptor-binding fragment-associated gene 9, Myh-1c, cytoplasmic dynein light chain 1, small membrane protein I and differential dependent protein. In contrast, expression in the PDT-resistant variants was downregulated for NNX3, human HepG2 3' region Mbol complementary DNA, glutamate dehydrogenase, hepatoma-derived growth factor and the mitochondrial genes coding for 16S ribosomal RNA (rRNA) and nicotinamide adenine dinucleotide (NADH) dehydrogenase subunit 4. The reduction for mitochondrial 16S rRNA in the PDT-resistant variants was confirmed by Northern blotting, and the elevated expression of the proapoptotic BNIP3 in the PDT-resistant variants was confirmed by Northern and Western blotting analysis. We also examined the expression of some additional apoptosis-regulating genes using Western blotting. We show an increased expression of Bcl-2 and heat shock protein 27 and a downregulation of Bax in the PDT-resistant variants. In addition, the mutant p53 levels in the parental HT29 cells were reduced substantially in the PDT-resistant variants. We suggest that the altered expression in several mitochondrial and apoptosis-regulating genes contributes to PDT resistance.
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PMID:Alterations in mitochondrial and apoptosis-regulating gene expression in photodynamic therapy-resistant variants of HT29 colon carcinoma cells. 1556 Jul 38

An Escherichia coli plasmid vector for the high-level expression of hydrophobic membrane proteins is described. The plasmid, pBCL, directs the expression of a target polypeptide fused to the C terminus of a mutant form of the anti-apoptotic Bcl-2 family protein, Bcl-XL, where the hydrophobic C terminus has been deleted, and Met residues have been mutated to Leu to facilitate CNBr cleavage after a single Met inserted at the beginning of the target sequence. Fusion protein expression is in inclusion bodies, simplifying the protein purification steps. Here we report the high-level production of PLM, a membrane protein that is a member of the FXYD family of tissue-specific and physiological-state-specific auxiliary subunits of the Na,K-ATPase, expressed abundantly in heart and skeletal muscle. We demonstrate that milligram quantities of pure, isotopically labeled protein can be obtained easily and in little time with this system.
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PMID:Bcl-XL as a fusion protein for the high-level expression of membrane-associated proteins. 1574 45

Apoptosis-inducing factor (AIF) is a mitochondrial intermembrane flavoprotein that is translocated to the nucleus in response to proapoptotic stimuli, where it induces nuclear apoptosis. Here we show that AIF is synthesized as an approximately 67-kDa preprotein with an N-terminal extension and imported into mitochondria, where it is processed to the approximately 62-kDa mature form. Topology analysis revealed that mature AIF is a type-I inner membrane protein with the N-terminus exposed to the matrix and the C-terminal portion to the intermembrane space. Upon induction of apoptosis, processing of mature AIF to an approximately 57-kDa form occurred caspase-independently in the intermembrane space, releasing the processed form into the cytoplasm. Bcl-2 or Bcl-XL inhibited both these events. These findings indicate that AIF release from mitochondria occurs by a two-step process: detachment from the inner membrane by apoptosis-induced processing in the intermembrane space and translocation into the cytoplasm. The results also suggest the presence of a unique protease that is regulated by proapoptotic stimuli in caspase-independent cell death.
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PMID:Export of mitochondrial AIF in response to proapoptotic stimuli depends on processing at the intermembrane space. 1577 70

The latent membrane protein (LMP1) encoded by Epstein-Barr virus (EBV) has been suggested to be one of the major oncogenic factors in EBV-mediated carcinogenesis. RNA-cleaving DNA enzymes are catalytic nucleic acids that bind and cleave a target RNA in a highly sequence-specific manner. In this study, we explore the potential of using DNAzymes as a therapeutic approach to EBV-associated carcinomas by targeting the LMP1 gene. In all, 13 different phosphorothioate-modified "10-23" deoxyribozymes (DNAzymes) were designed and synthesized against the LMP1 mRNA and transfected into B95-8 cells, which constitutively express the LMP1. Fluorescence microscopy was used to examine the cellular uptake and distribution in B95-8 cells. As demonstrated in Western blots, three out of 13 deoxyribozymes significantly downregulated the expression of LMP1 in B95-8 cells. These DNAzymes were shown to markedly inhibit B95-8 cell growth compared with a disabled DNAzyme and untreated controls, as determined by an alamarBlue Assay. It was further demonstrated that these DNAzymes arrested the B95-8 cells in G0/G1 using flow cytometry. Interestingly, the active DNAzymes could also downregulate the expression of Bcl-2 gene in treated cells, suggesting a close association between the LMP1 and Bcl-2 genes and their involvement in apoptosis. This was further confirmed with the result that the DNAzymes could induce the release of cytochrome c from mitochondria, which is the hallmark of the apoptosis. The present results suggest that the LMP1 may present a potential target for DNAzymes towards the EBV-associated carcinoma through cell proliferation and apoptosis pathways.
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PMID:Effect of EBV LMP1 targeted DNAzymes on cell proliferation and apoptosis. 1580 42

The aim of this study was to discuss the relevance of the Epstein-Barr virus (EBV) in the nasopharyngeal carcinoma (NPC), analyzing the variations of several molecules potentially involved in the pathogenesis of this cancer. EBV was detected in all the NPC samples by several techniques including PCR, in situ hybridization, and immunohistochemical methodologies. CD21 membrane receptor was absent after EBV infection, being a differential morphological feature of the tumoral cells. Latent membrane protein-1 (LMP1), an oncogenic viral product, was detected in a high percentage of samples, supporting a role for EBV in the pathogenesis of NPC. Bcl-2, an anti-apoptotic protein up-regulated by LMP1, was also overexpressed, coinciding with the majority of samples positive for LMP1. Finally, p53 presented abnormalities only in a low percentage of samples. These results reinforce the role of the EBV in the NPC discussing several potential mechanisms of pathogenesis in this neoplasia.
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PMID:Involvement of the Epstein-Barr virus in the nasopharyngeal carcinoma pathogenesis. 1596 73


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