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)

Changes in the intracellular reduced/oxidized glutathione ratio (GSH/GSSG) are crucial reduction-oxidation (redox) events that trigger downstream proliferation or death responses. We investigated the molecular mechanisms underlying redox-mediated cell signaling upon an oxidative insult by treating U937 cells with exogenous nonpermeable GSSG. This treatment results in a significant decrease of exofacial cell membrane thiol groups and intracellular decrement of GSH content, owing to its engagement in the formation of mixed disulfides. Changes in thioredoxin redox state were also observed, and they may be related to the activation of upstream ASK1 and selective induction of downstream p38 mitogen-activated protein kinase (MAPK) pathway, detectable by phosphorylation of MKK3/6 and p38 MAPK. Moreover, an increase in reactive oxygen species production was detected, and cells were committed to apoptosis along the mitochondrial pathway, evidenced by Bcl-2 down-regulation, cytochome c release from mitochondria, caspase-9 cleavage, and caspase-3 activation. GSH ethyl ester, a precursor of GSH, by counteracting intracellular mixed disulfide formation, canceled both p38 MAPK activation and GSSG-mediated apoptosis via inhibition of thioredoxin oxidation and stabilization of thioredoxin/ASK1 complex, whereas, blockage of p38 MAPK by specific inhibitor SB 203580 allowed apoptosis at a very reduced extent. Results suggest that kinase cascade may serve as a primary transducer of cytoplasmic oxidative signals to the nucleus before apoptosis-inducing signals are activated.
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PMID:Glutathione disulfide induces apoptosis in U937 cells by a redox-mediated p38 MAP kinase pathway. 1242 21

Imexon is an aziridine-containing iminopyrrolidone with selective growth-inhibitory potency for multiple myeloma. Our previous research indicates that imexon induces mitochondrial alterations, oxidative stress, and apoptosis. This drug represents an interesting model drug with a nonmyelosuppressive profile to study the basic mechanisms leading to antitumor activity and resistance. The major purpose of this study was to characterize an imexon-resistant RPMI8226/I cell line that was developed from RPMI8226 cells by continuous exposure to imexon. No significant differences were observed in the sensitivity to several cytotoxic drugs, including mitoxantrone, mitomycin C, melphalan, methotrexate, cytarabine, cisplatin, vincristine, and paclitaxel, in the imexon-resistant cells. However, RPMI8226/I cells were cross-resistant to arsenic trioxide, doxorubicin, fluorouracil, etoposide, irinotecan, and especially IFN-alpha. The data from DNA microarray and Western blot analyses indicated that the levels of antiapoptotic proteins Bcl-2 and thioredoxin-2, which reside mainly in the mitochondria, are increased in RPMI8226/I cells. In addition, increased levels of lung resistance protein were detected in imexon-resistant cells. Expression of P-glycoprotein was not detected in RPMI8226/I cells. No loss of mitochondrial membrane potential or increase in the levels of reactive oxygen species was observed in RPMI8226/I cells after exposure to imexon; however, the levels of glutathione are increased in the RPMI8226/I cells. Transmission electron microscopy revealed significant changes in the mitochondrial morphology of RPMI8226/I cells, whereas no ultrastructural changes were observed in other cellular compartments. Imexon-resistant RPMI8226/I myeloma cells appear to have a unique mechanism of resistance that is associated with morphological alterations of mitochondria, increased protection against oxidative stress, elevated levels of glutathione, and enhanced expression of antiapoptotic mitochondrial proteins.
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PMID:Molecular and cellular characterization of imexon-resistant RPMI8226/I myeloma cells. 1246 13

Thioredoxin reductase (TrxR) in conjunction with thioredoxin (Trx) is a ubiquitous intracellular oxidoreductase system with antioxidant and redox regulatory roles. The properties of TrxR in combination with the functions of Trx position this system at the core of cellular thiol redox control and antioxidant defense. In some human tumors, the thioredoxin system is found over-expressed. Because of its role in stimulating cancer cell growth and as an inhibitor of apoptosis, the Trx system offers a target for the development of drugs to treat and prevent cancer. In a previous research, we successfully synthesized a novel organoselenium compound BBSKE(1,2-[bis(1,2-Benzisoselenazolone-3(2H)-ketone)]ethane, BBSKE, PCT: CN02/00412) targeting the TrxR, and it has demonstrated the inhibitory effect on the growth of a variety of human cancer cells from various organs. In this study, we investigated the inhibitory effect of BBSKE on TrxR activity in PC-3 and DU145 human prostate cancer cell lines, and its antitumoral effect on these two cell lines. Treatment of BBSKE inhibited the TrxR activity in both of the cell lines in a dose-dependent manner and it also inhibited the proliferation of these two cell lines in a dose-dependent manner. Cell cycle analysis showed S phase arrest in both of the cell lines following 48 h exposure to BBSKE. During the S arrest, analysis of cell cycle regulatory proteins demonstrated that BBSKE increased the protein levels of cyclinA, cyclinE, and P21, but decreased the levels of cyclinB1, cyclinD1, and Cdk4. Furthermore, BBSKE decreased the protein level of Bcl-2 but increased the level of Bax, and induced apoptosis in PC-3 and DU145 human prostate cancer cell lines. These results suggest that this novel TrxR inhibitor inhibits the proliferation of prostate cancer cells via S phase arrest and apoptosis in association with the regulation of multiple molecules in the cell cycle.
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PMID:A novel organoselenium compound induces cell cycle arrest and apoptosis in prostate cancer cell lines. 1296 29

Reactive oxygen species (ROS) play a crucial role in the pathophysiology of ischemic heart disease by causing cardiac dysfunction and cell death. Several redox-sensitive anti- and pro-apoptotic transcription factors including NFkappaB and AP-1 progressively and steadily increase in the heart as a function of the duration of ischemia and reperfusion. When the heart is preconditioned to ischemic stress by repeated short-term ischemia and reperfusion, NFkappaB remains high while AP-1 is lowered to almost baseline value. The anti-apoptotic gene Bcl-2 is downregulated in the ischemic/reperfused heart, while it is upregulated in the adapted myocardium. Cardioprotective abilities of the preconditioning are abolished when heart is pre-perfused with N-acetyl cysteine, a scavenger for ROS, suggesting the role of ROS in redox signaling. Mammalian heart is protected by several defense systems which include among others, redox-regulated protein, thioredoxin. Reperfusion of ischemic myocardium results in the downregulation of thioredoxin 1 (Trx 1) expression, which was upregulated in the preconditioned myocardium. The increased expression of Trx 1 is completely blocked with an inhibitor of Trx 1, CDDP, which also abolished cardioprotection afforded by ischemic adaptation. The cardioprotective role of Trx 1 is confirmed further with transgenic mouse hearts overexpressing Trx 1. The Trx 1 mouse hearts displayed significantly improved post-ischemic ventricular recovery and reduced myocardial infarct size and apoptosis as compared to the corresponding wild-type mouse hearts. Taken together, preconditioning appears to potentiate redox signaling, which converts the "death signal" into "survival signal."
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PMID:Preconditioning potentiates redox signaling and converts death signal into survival signal. 1465 70

We studied the mechanism of intra-mitochondrial death initiator caspase-9 activation by a redox response, in which hydrogen peroxide (H(2)O(2)) caused a subtle decrease in the inner membrane potential (Deltapsim) with little evidence of cytochrome c release. Initiation of the intra-mitochondrial autocleavage of procaspase-9 preceded the onset of caspase cascade induction in the cytosol. Purified mitochondria demonstrated procaspase-9 processing and releasing abilities when exposed to H(2)O(2). Bcl-2 overexpression caused accumulation of the active form caspase-9 in the mitochondria, rendering the cells resistant to the redox stress. Intriguingly, disulfide-bonded dimers of autoprocessed caspase-9 were generated in the mitochondria in the pre-apoptotic phase. Using a substrate-analog inhibitor, dimer formation of procaspase-9 was also detectable inside the mitochondria. Furthermore, thiol reductant thioredoxin blocked the caspase-9 activation step and the cell death induction. Thus, redox stress-responsive thiol-disulfide converting reactions in the mitochondrion seemed to mediate procaspase-9 assembly that allows autoprocessing. This study offers an explanation for the recent observation that Apaf-1-null cells can execute apoptosis, which can be blocked by Bcl-2, and supports the proposition that the cytochrome c-Apaf-1-procaspase-9 complex functions in the caspase amplification rather than in its initiation.
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PMID:Dimerization and processing of procaspase-9 by redox stress in mitochondria. 1474 74

Reperfusion of ischemic myocardium produces reactive oxygen species (ROS) and results in apoptotic cell death and DNA fragmentation. Several redox-sensitive anti- and pro- apoptotic transcription factors including nuclear factor kappaB (NF-kappaB) and heterodimeric transcription factor AP-1 progressively and steadily increase in the heart as a function of the duration of ischemia and reperfusion. When the heart is adapted to ischemic stress by repeated short-term ischemia and reperfusion, NF-kappaB remains high, while AP-1 is lowered to almost baseline value. The anti-apoptotic gene Bcl-2 is downregulated in the ischemic/reperfused heart, while it is upregulated in the adapted myocardium. Cardioprotective abilities of the adapted myocardium are abolished when heart is pre-perfused with N-acetyl cysteine to scavenge ROS, suggesting a role of redox signaling. Mammalian heart is protected by several defense systems, which include, among others, the redox-regulated protein thioredoxin. Reperfusion of ischemic myocardium results in the downregulation of thioredoxin 1 (Trx 1) expression, which was upregulated in the adapted myocardium. The increased expression of Trx 1 is completely blocked with an inhibitor of Trx 1, cis-diammine-dichloroplatinum, which also abolished cardioprotection afforded by ischemic adaptation. The cardioprotective role of Trx 1 is further confirmed with transgenic mouse hearts overexpressing Trx 1. The Trx 1 mouse hearts displayed significantly improved post-ischemic ventricular recovery and reduced myocardial infarct size and apoptosis compared to the corresponding wild-type mouse hearts. The results of this study implicate a crucial role of redox signaling in transmitting anti-death signal.
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PMID:Conversion of death signal into survival signal by redox signaling. 1497 12

The expressions of Bcl-2, Bax and thioredoxin (Trx) mRNAs after kainic acid (KA) injection with or without melatonin pre-treatment were examined by real-time quantitative reverse transcription polymerase chain reaction in rat hippocampus. Bcl-2, Bax, and Trx mRNA expressions after KA injection were significantly increased. Additionally, it was observed that melatonin or melatonin pre-treatment had no significant effect on the regulation of Trx mRNA. Pre-treatment with melatonin at the 30th minute before KA injection resulted in a significant depletion in Bcl-2, Bax and Trx mRNA expressions. However, our results showed that melatonin pre-treatment increases the ratio of Bcl-2 to Bax mRNA in short-term period.
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PMID:Altered gene expressions in rat hippocampus after kainate injection with or without melatonin pre-treatment. 1505 Jul 13

Amyloid beta-peptide (Abeta) is a major constituent of senile plaques in the brains of Alzheimer's disease (AD) patients. We have previously demonstrated ceramide production secondary to Abeta-induced activation of neutral sphingomyelinase (nSMase) in cerebral endothelial cells and oligodendrocytes, which may contribute to cellular injury during progression of AD. In this study, we first established the "Abeta --> nSMase --> ceramide --> free radical --> cell death" pathway in primary cultures of fetal rat cortical neurons. We also provided experimental evidence showing that S-nitrosoglutathione (GSNO), a potent endogenous antioxidant derived from the interaction between nitric oxide (NO) and glutathione, caused dose-dependent protective effects against Abeta/ceramide neurotoxicity via inhibition of caspase activation and production of reactive oxygen species (ROS). This GSNO-mediated neuroprotection appeared to involve activation of cGMP-dependent protein kinase (PKG), phosphatidylinositol 3-kinase (PI3K), and extracellular signal-regulated kinase (ERK). Activation of the cGMP/PKG pathway induced expression of thioredoxin and Bcl-2 that were beneficial to cortical neurons in antagonizing Abeta/ceramide toxicity. Consistently, exogenous application of thioredoxin exerted remarkable neuroprotective efficacy in our experimental paradigm. Results derived from the present study establish a neuroprotective role of GSNO, an endogenous NO carrier, against Abeta toxicity via multiple signaling pathways.
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PMID:Protective effects of S-nitrosoglutathione against amyloid beta-peptide neurotoxicity. 1574 90

Antisense bcl-2 therapy combined with chemotherapy has been proved to be effective in various tumors. However, the role played by antisense bcl-2 therapy alone is not clear. In this study, we compared the apoptosis and the protein profiles of antisense bcl-2 transfected human neuroblastoma SK-N-MC cells to the control cells. Flow cytometric data indicated that antisense bcl-2 transfection did not lead to more extensive apoptosis in SK-N-MC cells (14.9 +/- 3.8%) than the control cells (10.3 +/- 2.3%). The above observation was confirmed by fluorescence microscopy using Hoechst 33258 staining. However, antisense bcl-2 induced changes in the expression of various proteins as shown by proteomic comparison, which included the up-regulation of the anti-apoptotic and anti-oxidant protein thioredoxin. By western blot validation, thioredoxin was found to be up-regulated by 2.9-folds with the corresponding down-regulation of Bcl-2 by 2.1-folds. The up-regulation of thioredoxin may be a compensating mechanism for cell survival in neuroblastoma when Bcl-2 expression is suppressed, and it may to some extent attenuate the effectiveness of antisense bcl-2 therapy.
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PMID:Antisense bcl-2 transfection up-regulates anti-apoptotic and anti-oxidant thioredoxin in neuroblastoma cells. 1580 70

Delayed cardio- and neuroprotection are observed following a preconditioning procedure evoked by a brief and nontoxic oxidative stress due to deprivation of oxygen, glucose, serum, trophic factors, and/or antioxidative enzymes. Preconditioning protection can be observed in vivo and is under clinical trials for preservation of cell viability following organ transplants of liver. Previous studies indicated that ischemic preconditioning increases the expression of heat-shock proteins (HSPs) and nitric oxide synthase (NOS). Our pilot studies indicate that the treatment of neuronal NOS inhibitor (7-nitroindazole) and 6Br-cGMP blocks and mimics, respectively, preconditioning protection in human neuroblastoma SH-SY5Y cells. This minireview focuses on nitric oxide-mediated cellular adaptation and the related cGMP/PKG signaling pathway in a compensatory mechanism underlying preconditioning-induced hormesis. Both preconditioning and 6Br-cGMP increase the induction of human thioredoxin (Trx) mRNA and protein for cytoprotection, which is largely prevented by transfection of cells with Trx antisense but not sense oligonucleotides. Cytosolic Trx1 and mitochondrial Trx2 suppress free radical formation, lipid peroxidation, oxidative stress, and mitochondria-dependent apoptosis; knock out/down of either Trx1 or Trx2 is detrimental to cell survival. Other recent findings indicate that a transgenic increase of Trx in mice increases tolerance against oxidative nigral injury caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Trx1 can be translocated into nucleus and phosphoactivated CREB for a delayed induction of mitochondrial anti-apoptotic Bcl-2 and antioxidative MnSOD that is known to increase vitality and survival of cells in the brain and the heart. In conclusion, preconditioning adaptation or a brief oxidative stress induces a delayed nitric oxide-mediated compensatory mechanism for cell survival and vitality in the central nervous system and the cardiovascular system. Preconditioning-induced adaptive tolerance may be signaling through a cGMP-dependent induction of cytosolic redox protein Trx1 and subsequently mitochondrial proteins such as Bcl-2, MnSOD, and perhaps Trx2 or HSP70.
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PMID:Induction of thioredoxin and mitochondrial survival proteins mediates preconditioning-induced cardioprotection and neuroprotection. 1596 87


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