UNIPROT:P10415 - FACTA Search

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Query: UNIPROT:P10415 (Bcl-2)
33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cardiotonic steroids (CTS) like ouabain are not only specific inhibitors of the sodium pump (Na(+),K(+)-ATPase), they also can influence various cytosolic signaling events in a hormone-like manner. In the neuroblastoma cell line SH-SY5Y ouabain triggers multiple signaling pathways. Within 30 min of incubation with 1 or 10 microM ouabain, SH-SY5Y cells generate reactive oxygen species to a level approximately 50% above control and show a modest but significant elevation in cytosolic [Ca(2+)] of about 25%. After 6 h of exposure, ouabain stimulates a series of anti-apoptotic actions in SH-SY5Y cells, including concentration-dependent phosphorylation of Erk1/2, Akt, and Bad. Nevertheless, at the same time this CTS also induces a series of events that inhibit retinoic acid-induced neuritogenesis and promote cell death. Both of these latter phenomena are possibly associated with the observed ouabain-induced reduction in the abundance of the anti-apoptotic proteins Bcl-XL and Bcl-2. In addition, ouabain treatment results in cytochrome c release into the cytosol and induces activation of caspase 3, events that point towards the stimulation of apoptotic pathways that are probably enhanced by the stimulation of p53 phosphorylation at Ser15 also observed in this study. These pathways may eventually lead to cell death: treatment with 10 nM ouabain results in a 20% decrease in cell number after 4 days of incubation and treatment with 1 microM ouabain decreases cells number by about 75%. The results obtained here emphasize the importance of further research in order to elucidate the various signalling cascades triggered by ouabain and possibly other CTS that are used in the treatment of heart failure and to identify their primary receptor(s).
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PMID:Ouabain activates signaling pathways associated with cell death in human neuroblastoma. 1752 49

Sodium supplementation given for 1 wk to nonpregnant rats induces changes that are adequate to maintain renal and circulatory homeostasis as well as arterial blood pressure. However, in pregnant rats, proteinuria, fetal growth restriction, and placental oxidative stress are observed. Moreover, the decrease in blood pressure and expansion of circulatory volume, normally associated with pregnancy, are prevented by high-sodium intake. We hypothesized that, in these pregnant rats, a loss of the balance between prooxidation and antioxidation, particularly in kidneys and heart, disturbs the normal course of pregnancy and leads to manifestations such as gestational hypertension. We thus investigated the presence of oxidative/nitrosative stress in heart and kidneys following high-sodium intake in pregnant rats. Markers of this stress [8-isoprostaglandin F(2alpha) (8-iso-PGF(2alpha)) and nitrotyrosine], producer of nitric oxide [nitric oxide synthases (NOSs)], and antioxidants [superoxide dismutase (SOD) and catalase] were measured. Then, molecules (Na(+)-K(+)-ATPase and aconitase) or process [apoptosis (Bax and Bcl-2), inflammation (monocyte chemoattractant protein-1, connective tissue growth factor, and TNF-alpha)] susceptible to free radicals was determined. In kidneys from pregnant rats on 1.8% NaCl-water, NOSs, apoptotic index, and nitrotyrosine expression were increased, whereas Na(+)-K(+)-ATPase mRNA and activity were decreased. In the left cardiac ventricle of these rats, heightened nitrotyrosine, 8-iso-PGF(2alpha), and catalase activity together with reduced endothelial NOS protein expression and SOD and aconitase activities were observed. These findings suggest that oxidative/nitrosative stress in kidney and left cardiac ventricle destabilizes the normal course of pregnancy and could lead to gestational hypertension.
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PMID:Renal and cardiac oxidative/nitrosative stress in salt-loaded pregnant rat. 1765 67

We have shown that hypoxia results in increased influx of nuclear Ca++ and increased expression of nuclear apoptotic proteins. The present study tests the hypothesis that hypoxia alters the distribution of pro-apoptotic proteins Bad and Bax, and the anti-apoptotic proteins Bcl-xl, and Bcl-2 in the nuclear, mitochondrial and cytosolic compartments of the cerebral cortex of newborn piglets and the administration of Clonidine, an inhibitor of high affinity nuclear Ca++ -ATPase, will prevent the hypoxia-induced increase in apoptotic proteins' expression. Studies were conducted in 19 newborn piglets, 6 normoxic (Nx), 7 hypoxic and 6 Clonidine-treated hypoxic (Hx-Clo). Tissue hypoxia was documented biochemically by measuring cerebral tissue ATP and phosphocreatine (PCr) levels. Bax and Bad protein expression increased in all the three compartments during hypoxia, while there was no significant change in the expression of anti-apoptotic proteins Bcl-2 and Bcl-xl. In Clonidine pretreated hypoxic group, the hypoxia-induced increased expression of pro-apoptotic proteins Bad and Bax was prevented in all the three fractions. We conclude that hypoxia results in increased expression of pro-apoptotic proteins in nuclear, mitochondrial and cytosolic compartments and that the increased expression of pro-apoptotic proteins during hypoxia is nuclear Ca++ -influx-dependent. We propose that during hypoxia the increased ratio of (pro-apoptotic Bad and Bax/anti-apoptotic Bcl-xl and Bcl-2) in all the three compartments, will lead to altered mitochondrial and nuclear membrane permeability as well as caspase-9 activation in the cytosolic compartment.
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PMID:Effect of hypoxia on expression of apoptotic proteins in nuclear, mitochondrial and cytosolic fractions of the cerebral cortex of newborn piglets: the role of nuclear Ca++ -influx. 1829 86

BI-1 (Bax inhibitor-1) is an evolutionarily conserved multitransmembrane protein that resides in the endoplasmic reticulum (ER) and that has documented cytoprotective functions in both animals and plants. Recent studies indicate that BI-1 shares in common with Bcl-2/Bax family proteins the ability to regulate the amounts of Ca(2+) that can be released from the ER by agents, such as the ER-Ca(2+)-ATPase (SERCA) inhibitor thapsigargin (TG). Using an ER-targeted, Ca(2+) indicator (cameleon), with characteristics optimized for measuring ER Ca(2+) ([Ca(2+)](er)), we studied the effects of BI-1 on [Ca(2+)](er) in resting and TG-treated cells. Similar to cells overexpressing antiapoptotic Bcl-2 or Bcl-X(L), overexpression of BI-1 resulted in lower resting [Ca(2+)](er), with concomitantly less Ca(2+) released into the cytosol upon stimulation by TG and with a higher rate of Ca(2+) leakage from the ER. Co-expression of SERCA restored levels of [Ca(2+)](er) to normal, showing opposing actions of the ER-Ca(2+)ATPase and BI-1 on ER Ca(2+) homeostasis. Conversely, cells with deficient BI-1 have increased [Ca(2+)](er), and release more Ca(2+) into the cytosol when challenged with TG. In BI-1-deficient cells, Bcl-X(L) fails to reduce [Ca(2+)](er), indicating that BI-1 functions downstream of Bcl-X(L). In bax(-/-)bak(-/-) double knock-out cells, both BI-1 and Bcl-X(L) retained their ability to reduce [Ca(2+)](er), suggesting that BI-1 and Bcl-X(L) operate downstream of or parallel to Bax/Bak. The findings reveal a hierarchy of functional interactions of BI-1 with Bcl-2/Bax family proteins in regulating ER Ca(2+) homeostasis.
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PMID:BI-1 regulates endoplasmic reticulum Ca2+ homeostasis downstream of Bcl-2 family proteins. 1829 29

Intracellular calcium is a major coordinator of numerous aspects of cellular physiology, including muscle contractility and cell survival. In cardiac muscle, aberrant Ca(2+) cycling has been implicated in a range of pathological conditions including cardiomyopathies and heart failure. The sarco(endo)plasmic reticulum Ca(2+) transport adenosine triphosphatase (SERCA2a) and its regulator phospholamban (PLN) have a central role in modulating Ca(2+) homeostasis and, therefore, cardiac function. Herein, we discuss the mechanisms through which SERCA2a and PLN control cardiomyocyte function in health and disease. Emphasis is placed on our newly identified PLN-binding partner HS-1-associated protein X-1 (HAX-1), which has an anti-apoptotic function and presents with numerous similarities to Bcl-2. Recent evidence indicates that proteins of the Bcl-2 family can influence ER Ca(2+) content, a critical determinant of cellular sensitivity to apoptosis. The discovery of the PLN/HAX-1 interaction therefore unveils an important new link between Ca(2+) homeostasis and cell survival, with significant therapeutic potential.
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PMID:The role of SERCA2a/PLN complex, Ca(2+) homeostasis, and anti-apoptotic proteins in determining cell fate. 1841 21

A wave of beta cell apoptosis occurs around 2 weeks of age in rats and mice. We have previously reported that exposure in utero to bafilomycin, a plecomacrolide antibiotic that inhibits the vacuolar (v)ATPase enzyme and contaminates the human diet, delays this neonatal wave and accelerates diabetes in non-obese diabetic (NOD) mice. Here we exposed C57BL/6J mice in utero to bafilomycin and assessed the effects on islet morphology, apoptosis and activation of cell survival signaling in beta cells. The neonatal wave of beta cell apoptosis was associated with high expression and low phosphorylation of the pro-apoptotic Bcl-2 family protein Bad, whereas after weaning (3 weeks of age) Bad was down-regulated and beta cell apoptosis was low. In contrast, in bafilomycin-exposed mice the frequency of apoptotic beta cells and the expression of Bad remained high after weaning. Bafilomycin exposure also inactivated the insulin/IGF signaling pathway intermediate, FoxO1, and increased the insulin content in neonatal islets. Thus, exposure in utero to bafilomycin disrupts the regulation of Bad in neonatal beta cells, increases cell survival signaling and delays the neonatal wave of apoptosis. Increased expression of Bad in adult beta cells provides an explanation for accelerated diabetes in bafilomycin-exposed NOD mice, whereby disruption of neonatal islet-cell turnover may render the adult beta cells more susceptible to induced cell death.
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PMID:Transplacental exposure to the vacuolar-ATPase inhibitor bafilomycin disrupts survival signaling in beta cells and delays neonatal remodeling of the endocrine pancreas. 1848 61

Bz-423 is a proapoptotic 1,4-benzodiazepine with potent therapeutic properties in murine models of lupus and psoriasis. Bz-423 modulates the F(1)F(0)-ATPase, inducing the formation of superoxide within the mitochondrial respiratory chain, which then functions as a second messenger initiating apoptosis. Herein, we report the signaling pathway activated by Bz-423 in mouse embryonic fibroblasts containing knockouts of key apoptotic proteins. Bz-423-induced superoxide activates cytosolic ASK1 and its release from thioredoxin. A mitogen-activated protein kinase cascade follows, leading to the specific phosphorylation of JNK. JNK signals activation of Bax and Bak which then induces mitochondrial outer membrane permeabilization to cause the release of cytochrome c and a commitment to apoptosis. The response of these cells to Bz-423 is critically dependent on both superoxide and JNK activation as antioxidants and the JNK inhibitor SP600125 prevents Bax translocation, cytochrome c release, and cell death. These results demonstrate that superoxide generated from the mitochondrial respiratory chain as a consequence of a respiratory transition can signal a sequential and specific apoptotic response. Collectively, these data suggest that the selectivity of Bz-423 observed in vivo results from cell-type specific differences in redox balance and signaling by ASK1 and Bcl-2 proteins.
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PMID:Bz-423 superoxide signals apoptosis via selective activation of JNK, Bak, and Bax. 1871 27

Na,K-ATPase is a ubiquitous transmembrane protein that regulates and maintains the intracellular Na(+) and K(+) gradient necessary for cell homeostasis. Recently, the importance of this pump in external stimuli-induced leukemia cell apoptosis has been increasingly appreciated, however, the exact role of Na,K-ATPase in mitochondrial apoptotic pathway still remains little understood. In this study, we found mitochondrial toxin rotenone caused a rapid mitochondrial membrane potential (MMP) collapse in Jurkat cells followed by plasma membrane depolarization (PMP). Similar results were also obtained in human U937 cells and non-cancerous mouse primary T cells. Rotenone-induced PMP depolarization occurred before apoptosis and well correlated with Na,K-ATPase impairment. To understand the mechanisms, Jurkat cells with mtDNA depletion and catalase overexpression were used. The results demonstrated that both PMP depolarization and Na,K-ATPase impairment induced by rotenone were regulated by mitochondrial H(2)O(2) and Bcl-2. Finally, Na,K-ATPase suppression by ouabain greatly accelerated and enhanced mitochondrial toxins-induced cells apoptosis in Jurkat, U937 and primary T cells. In sum, by using leukemia cells and mouse primary T cells, we confirmed that mitochondria-to-Na,K-ATPase and PMP depolarization might represent a novel mechanism for mitochondria to amplify death signals in the initiation stage of cells apoptosis induced by mitochondrial toxins.
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PMID:Plasma membrane depolarization and Na,K-ATPase impairment induced by mitochondrial toxins augment leukemia cell apoptosis via a novel mitochondrial amplification mechanism. 1944 64

The anti-apoptotic oncoproteins Bcl-2 and Bcl-xL play crucial roles in tumorigenesis and chemoresistance, and are thus therapeutic cancer targets. We searched for small molecules that disturbed the anti-apoptotic function of Bcl-2 or Bcl-xL, and found vacuolar H(+)-ATPase (V-ATPase) inhibitors, such as bafilomycin A1 (BMA), that showed such activity. Bcl-xL-overexpressing Ms-1 cells displayed resistance to anticancer drugs, but underwent apoptosis following treatment with a combination of V-ATPase inhibitors at doses similar to those that caused inhibitory activities of V-ATPase. We investigated the apoptosis mechanism induced by cotreatment of Bcl-xL-overexpressing Ms-1 cells with BMA as a V-ATPase inhibitor and taxol (TXL) as an anticancer drug. With BMA, TXL triggered mitochondrial membrane potential loss and cytochrome c release, whereas downstream caspase activation was not observed. In contrast, pronounced nuclear translocation of mitochondrial apoptosis-inducing factor and endonuclease G, known as effectors of caspase-independent apoptosis, was observed with BMA and TXL cotreatment. Moreover, depletion of apoptosis-inducing factor and endonuclease G using each siRNA significantly rescued cells from BMA- and TXL-induced apoptosis. Hence, the apoptosis-inducing factor- and endonuclease G-dependent pathway was critical for apoptosis induction by BMA and TXL cotreatment. Our data suggest that V-ATPase inhibitors could not only suppress anti-apoptotic Bcl-2 nor Bcl-xL but could also facilitate the caspase-independent apoptotic pathway. V-ATPase inhibition will be a promising therapeutic approach for Bcl-2- or Bcl-xL-overexpressing malignancies.
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PMID:Vacuolar H+-ATPase inhibitors overcome Bcl-xL-mediated chemoresistance through restoration of a caspase-independent apoptotic pathway. 1945 57

Accumulating evidence suggests that endoplasmic reticulum (ER) stress by mechanisms that include ER Ca(2+) depletion via NO-dependent down-regulation of sarcoendoplasmic reticulum Ca(2+) ATPase 2b (SERCA2b) contributes to beta-cell death in type 1 diabetes. To clarify whether the molecular pathways elicited by NO and ER Ca(2+) depletion differ, we here compare the direct effects of NO, in the form of the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP), with the effects of SERCA2 inhibitor thapsigargin (TG) on MAPK, nuclear factor kappaB (NFkappaB), Bcl-2 proteins, ER stress, and apoptosis. Exposure of INS-1E cells to TG or SNAP caused caspase-3 cleavage and apoptosis. Both TG and SNAP induced activation of the proapoptotic transcription factor CCAAT/enhancer-binding protein homologous protein (CHOP). However, other classical ER stress-induced markers such as up-regulation of ER chaperone Bip and alternative splicing of the transcription factor Xbp-1 were exclusively activated by TG. TG exposure caused NFkappaB activation, as assessed by IkappaB degradation and NFkappaB DNA binding. Inhibition of NFkappaB or the Bcl-2 family member Bax pathways protected beta-cells against TG- but not SNAP-induced beta-cell death. These data suggest that NO generation and direct SERCA2 inhibition cause two quantitative and qualitative different forms of ER stress. In contrast to NO, direct ER stress induced by SERCA inhibition causes activation of ER stress signaling pathways and elicit proapoptotic signaling via NFkappaB and Bax.
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PMID:Inhibition of nuclear factor-kappaB or Bax prevents endoplasmic reticulum stress- but not nitric oxide-mediated apoptosis in INS-1E cells. 1955 21

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