Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CED-4, a pro-apoptotic factor in Caenorhabditis elegans, activates the cell death protease CED-3. CED-9 directly binds to CED-4 and represses this. However, it has remained unclear whether a mammalian CED-9 homologue, Bcl-XL, inhibits the function of the mammalian CED-4 homologue, Apaf-1, by direct binding. To analyze the interaction, we adopted a yeast two-hybrid system. Since Bcl-XL and the CED-4-like portion of Apaf-1 failed to exhibit a positive result in the assay, we prepared "fragment libraries" of bcl-XL or apaf-1 cDNA. By screening of the apaf-1 "fragment library," we obtained nine clones interacting with Bcl-XL, all containing the same region within the ATPase domain, designated BBR: the Bcl-XL binding region. Binding of BBR to Bcl-XL was also confirmed by immunoprecipitation assays. Bcl-2, Bcl-w, A1/Bfl-1, and Boo/Diva failed to show the same capacity for binding to BBR as Bcl-XL. These results indicate that Bcl-XL directly binds to a specific region in Apaf-1.
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PMID:Identification of a Bcl-XL binding region within the ATPase domain of Apaf-1. 1296 20

Selection of tumor cell lines with anticancer drugs has led to the appearance of multidrug-resistant (MDR) subclones with P-glycoprotein 1 (P-gp1) expression. These cells are cross-resistant to several structurally and functionally dissimilar drugs. Interestingly, in the process of gaining resistance, MDR cells become hypersensitive or collaterally sensitive to membrane-active agents, such as calcium channel blockers, steroids, and local anaesthetics. In this report, hypersensitivity to the calcium channel blocker, verapamil, was analyzed in sensitive and resistant CHO cell lines. Our results show that treatment with verapamil preferentially induced apoptosis in MDR cells compared to drug-sensitive cells. This effect was independent of p53 activity and could be inhibited by overexpression of the Bcl-2 gene. The induction of apoptosis by verapamil had a biphasic trend in which maximum cell death occurred at 10 microM, followed by improved cell survival at higher concentrations (50 microM). We correlated this effect to a similar biphasic trend in P-gp1 ATPase activation by verapamil in which low concentrations of verapamil (10 microM) activated ATPase, followed by inhibition at higher concentrations. To confirm the relationship between apoptosis and ATPase activity, we used two inhibitors of P-gp1 ATPase, PSC 833 and ivermectin. These ATPase inhibitors reduced hypersensitivity to verapamil in MDR cells. In addition, low concentrations of verapamil resulted in the production of reactive oxygen species (ROS) in MDR cells. Taken together, these results show that apoptosis was preferentially induced by P-gp1 expressing cells exposed to verapamil, an effect that was mediated by ROS, produced in response the high ATP demand by P-gp1.
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PMID:A mechanism for P-glycoprotein-mediated apoptosis as revealed by verapamil hypersensitivity. 1456 77

A multidrug resistant (MDR) cell line, derived from the human leukaemic cell K562 and selected for its resistance to Vincristine, was shown to be resistant to Thapsigargin (TG). A concentration of 50 nM TG was toxic to K562 cells whereas the MDR cell line, known as Lucena I cells, survived unaffected for up to seven days in culture. Similarly, no intracellular Ca2+ mobilization was observed in the MDR cell line treated with TG. This effect was not a result of TG extrusion by P glycoprotein (Pgp), as no mobilization was observed even in the presence of the Pgp inhibitors Verapamil (5 microM) and Cyclosporin A (0.16 microM). In the present study, both cell lines expressed comparable levels of Bcl-2 making it unlikely that Bcl-2 was involved in this process. Similarly, no overexpression of the endoplasmic reticulum Ca2+ ATPase (SERCA) could be detected in the MDR cell line and Ca2+ uptake by vesicles of the two cell types were equally sensitive to TG. These results confirm that MDR cells do not mobilize Ca2+ in the presence of TG but go against the possibility that this might be due to TG extrusion or to the overexpression of a resistant SERCA isoform.
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PMID:Resistance to thapsigargin-induced intracellular calcium mobilization in a multidrug resistant tumour cell line. 1457 83

Neuroendocrine (NE) differentiation is a hallmark of advanced, androgen-independent prostate cancer, for which there is no successful therapy. NE tumor cells are nonproliferating and escape apoptotic cell death; therefore, an understanding of the apoptotic status of the NE phenotype is imperative for the development of new therapies for prostate cancer. Here, we report for the first time on alterations in intracellular Ca(2+) homeostasis, which is a key factor in apoptosis, caused by NE differentiation of androgen-dependent prostate cancer epithelial cells. NE-differentiating regimens, either cAMP elevation or androgen deprivation, resulted in a reduced endoplasmic reticulum Ca(2+)-store content due to both SERCA 2b Ca(2+) ATPase and luminal Ca(2+) binding/storage chaperone calreticulin underexpression, and to a downregulated store-operated Ca(2+) current. NE-differentiated cells showed enhanced resistance to thapsigargin- and TNF-alpha-induced apoptosis, unrelated to antiapoptotic Bcl-2 protein overexpression. Our results suggest that targeting the key players determining Ca(2+) homeostasis in an attempt to enhance the proapoptotic potential of malignant cells may prove to be a useful strategy in the treatment of advanced prostate cancer.
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PMID:Ca2+ homeostasis and apoptotic resistance of neuroendocrine-differentiated prostate cancer cells. 1468 64

Solid-state NMR spectroscopy is being used to determine the structures of membrane proteins involved in the regulation of apoptosis and ion transport. The Bcl-2 family includes pro- and anti-apoptotic proteins that play a major regulatory role in mitochondrion-dependent apoptosis or programmed cell death. The NMR data obtained for (15)N-labeled anti-apoptotic Bcl-xL in lipid bilayers are consistent with membrane association through insertion of the two central hydrophobic alpha-helices that are also required for channel formation and cytoprotective activity. The FXYD family proteins regulate ion flux across membranes, through interaction with the Na(+), K(+)-ATPase, in tissues that perform fluid and solute transport or that are electrically excitable. We have expressed and purified three FXYD family members, Mat8 (mammary tumor protein), CHIF (channel-inducing factor) and PLM (phospholemman), for structure determination by NMR in lipids. The solid-state NMR spectra of Bcl-2 and FXYD proteins, in uniaxially oriented lipid bilayers, give the first view of their membrane-associated architectures.
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PMID:Structural studies of apoptosis and ion transport regulatory proteins in membranes. 1474 97

We reported that the endoplasmic reticulum (ER) stress pathway involving CHOP, a member of the C/EBP transcription factor family, plays a key role in nitric oxide (NO)-mediated apoptosis of macrophages and pancreatic beta cells. We also showed that the cytosolic chaperone pair of hsp70 and dj1 (hsp40/hdj-1) or dj2 (HSDJ/hdj-2) prevents NO-mediated apoptosis upstream of cytochrome c release from mitochondria. To analyze roles of the chaperone pair in preventing apoptosis, RAW 264.7 macrophages stably expressing hsp70 and dj1 or dj2 were established. The chaperone pair prevented LPS/IFN-gamma-induced and NO-mediated apoptosis downstream of CHOP induction. hsp70 mutant protein lacking the ATPase domain or the C-terminal EEVD sequence were not effective in preventing CHOP-induced apoptosis. A mutant dj2 lacking the C-terminal prenylation CaaX motif, was also not effective. When wild-type RAW 264.7 cells were treated with LPS/IFN-gamma, NO-mediated apoptosis was induced, and proapoptotic Bcl-2 family protein Bax was translocated from cytosol to mitochondria. This translocation was prevented in cells stably expressing hsp70/dj2, and in CHOP knockout cells. Overexpression of CHOP in wild-type cells also induced translocation of Bax and this translocation was prevented in cells expressing hsp70/dj2. CHOP-induced apoptosis was prevented by Bax knock-down. Coimmunoprecipitation experiments showed that Bax interacts with both hsp70 and dj1/dj2. ATPase domain of hsp70 was necessary for the binding with Bax. These findings indicate that CHOP-induced apoptosis is mediated by translocation of Bax from the cytosol to the mitochondria, and hsp70/dj1 or dj2 chaperone pair prevents apoptosis by interacting with Bax and preventing translocation to the mitochondria.
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PMID:hsp70-DnaJ chaperone pair prevents nitric oxide- and CHOP-induced apoptosis by inhibiting translocation of Bax to mitochondria. 1475 10

Nitric oxide (NO) is a potent inducer of apoptosis, and its cytotoxicity is closely related to mitochondrial dysfunction. In this study we investigated the effects of a F0F1-ATPase inhibitor, oligomycin, and a mitochondrial respiratory chain complex III inhibitor, antimycin A, on NO-induced apoptosis. We used a normal rat gastric-epithelium cell line, RGM-1, treated with a pure NO donor, NOC-1 -1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene - in the presence or absence of oligomycin or antimycin A. Changes in the expressions of Bax or Bcl-2 proteins, release of cytochrome C from mitochondria into the cytosol, activation of caspase-3, and changes in the mitochondrial membrane potential (DeltaPsi) were measured with the use of Western blotting, c43 lorimetric assays, and a mitochondrial potential sensor, JC-1 dye. Treatment with NOC-18 induced dose-dependent apoptotic cell death in RGM-1 cells. Cell death was accompanied by mitochondrial depolarization, increases in Bax protein expression and cytochrome C leakage, and, subsequently, caspase-3 activation. Oligomycin and antimycin A prevented NO-induced apoptosis in a dose-dependent fashion by preventing cytochrome C release independent of Bcl-2 expression. However, neither compound affected the up-regulation of Bax protein. On the one hand, oligomycin treatment was not accompanied by a decline in DeltaPsi. On the other hand, antimycin A treatment decreased DeltaPsi regardless of NOC-18 treatment. The findings of this study suggest that various functional molecules that constitute the mitochondrial respiratory chain may contribute to cytochrome C release that occurs during NO-induced apoptosis.
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PMID:Oligomycin and antimycin A prevent nitric oxide-induced apoptosis by blocking cytochrome C leakage. 1500 3

The antiapoptotic protein Bcl-2 is targeted to the mitochondria, but it is uncertain whether Bcl-2 affects only myocyte survival after ischemia, or whether it also affects metabolic functions of mitochondria during ischemia. Hearts from mice overexpressing human Bcl-2 and from their wild-type littermates (WT) were subjected to 24 minutes of global ischemia followed by reperfusion. During ischemia, the decrease in pH(i) and the initial rate of decline in ATP were significantly reduced in Bcl-2 hearts compared with WT hearts (P<0.05). The reduced acidification during ischemia was dependent on the activity of mitochondrial F1F0-ATPase. In the presence of oligomycin (Oligo), an F1F0-ATPase inhibitor, the decrease in pH(i) was attenuated in WT hearts, but in Bcl-2 hearts, Oligo had no additional effect on pH(i) during ischemia. Likewise, addition of Oligo to WT hearts slowed the rate of decline in ATP during ischemia to a level similar to that observed in Bcl-2 hearts, but addition of Oligo had no significant effect on the rate of decline in ATP in Bcl-2 hearts during ischemia. These data are consistent with Bcl-2-mediated inhibition of consumption of glycolytic ATP. Furthermore, mitochondria from Bcl-2 hearts have a reduced rate of consumption of ATP on uncoupler addition. This could be accomplished by limiting ATP entry into the mitochondria through the voltage-dependent anion channel, and/or the adenine nucleotide transporter, or by direct inhibition of the F1F0-ATPase. Immunoprecipitation showed greater interaction between Bcl-2 and voltage-dependent anion channel during ischemia. These data indicate that Bcl-2 modulation of metabolism contributes to cardioprotection.
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PMID:Transgenic expression of Bcl-2 modulates energy metabolism, prevents cytosolic acidification during ischemia, and reduces ischemia/reperfusion injury. 1534 51

Neuron viability and defense against neurodegenerative disease can be achieved by targeting mitochondrial function to reduce oxidative stress, increase mitochondrial defense mechanisms, or promote energetic metabolism and Ca2+ homeostasis. Exposure to estrogen prior to contact with toxic agents can protect neurons against a wide range of degenerative insults. The proactive defense state induced by estrogen is mediated by complex mechanisms ranging from chemical to biochemical to genomic but which converge upon regulation of mitochondria function. Estrogen preserves ATP levels via increased/enhanced oxidative phosphorylation and reduced ATPase activity thereby increasing mitochondrial respiration efficiency, resulting in a lower oxidative load. In addition, estrogen increases antiapoptotic proteins, Bcl-2 and Bcl-xL, which prevents activation of the permeability transition pore protecting against estrogen-induced increase in mitochondrial Ca2+ sequestration. These effects are likely to be enhanced by antioxidant effects of estrogen, preventing the initiation of the deleterious "mitochondrial spiral". The extent to which each of these mechanisms contribute to the overall proactive defense state induced by estrogen remains to be determined. However, each aspect of the cascade appears to make a significant if not obligatory impact on the neuroprotective effects of estrogens. Moreover each component of the cascade is required for estrogen regulation of mitochondrial function. Mechanisms of estrogen action and results of the clinical efficacy of estrogen therapy for prevention or treatment of Alzheimer's disease are considered in the context of clinical use of estrogen therapy and the design of brain selective estrogens or NeuroSERMs.
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PMID:Mitochondria as therapeutic targets of estrogen action in the central nervous system. 1537 6

Heat stress results in cardiac dysfunction and even cardiac failure. To elucidate the cellular and molecular mechanism of cardiomyocyte injury induced by heat stress, the changes of structure and function in cardiac mitochondria of heat-exposed Wistar rats and its role in cardiomyocyte injury were investigated. Heat stress induced apoptosis and necrosis of cardiomyocytes in a time- and dose-dependent fashion. In the mitochondria of heat-stressed cardiomyocytes, the respiratory control rate and oxidative phosphorylation efficiency (P:O) were decreased gradually with the rise of rectal temperature. The Ca2+ -adenosine triphosphatase activity and Ca2+ content were also reduced. Exposing isolated mitochondria to the heat stress induced special internal environmental states including Ca2+ overload, oxidative stress, and altered mitochondrial membrane permeability transition (MPT). In vivo, the heat stress-induced mitochondrial MPT alteration was also found. The changes of mitochondrial MPT resulted in the release of cytochrome c from mitochondria into the cytosol, and in turn, caspase-3 was activated. Transfection of bcl-2 caused Bcl-2 overexpression in cardiomyocyte, which protected the mitochondria and reduced the heat stress-induced cardiomyocyte injury. In conclusion, it appears that the destruction of mitochondrial structure and function not only resulted in the impairment of physiological function of cardiomyocytes under heat stress but may also further lead to severe cellular injury and even cell death. These findings underline the contribution of mitochondria to the injury process in cardiomyocytes under heat stress.
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PMID:Mitochondrial mechanism of heat stress-induced injury in rat cardiomyocyte. 1554 66


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