Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study, we examined how the cell survival signaling via cyclic AMP-responsive element binding protein (CREB) and Akt, and the cell death signaling via cystein proteases, calpain and caspase-3, are involved in oxygen-glucose deprivation (OGD) followed by reoxygenation (OGD/reoxygenation)-induced cell death in nerve growth factor (NGF)-differentiated PC12 cells. OGD/reoxygenation-induced cell death was evaluated by LDH release into the culture medium. The level of LDH release was low (9.0% +/- 4.1%) immediately after 4 hr of OGD (0 hr of reoxygenation), was significantly increased to 28.6% +/- 6.6% at 3 hr of reoxygenation, and remained at similar levels at 6 and 20 hr of reoxygenation, suggesting that reoxygenation at least for 3 hr resulted in the loss of cell membrane integrity. After 4 hr of OGD followed by 3 hr of reoxygenation, dephosphorylation of phosphorylated CREB (pCREB), but not phosphorylated Akt (pAkt), was induced. Under these conditions, calpain- but not caspase-3-mediated alpha-spectrin breakdown product was increased, indicating that OGD/reoxygenation also induced an increase in calpain activity. The restoration of pCREB by protein phosphatase (PP)-1/2A inhibitors or the inhibition of excessive activation of calpain by calpain inhibitor did not reduce OGD/reoxygenation-induced LDH release. Cotreatment with PP-1/2A and calpain inhibitors reduced OGD/reoxygenation-induced LDH release. The present study suggests that a balance in the phosphorylation and proteolytic signaling is involved in the survival of NGF-differentiated PC12 cells.
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PMID:Dual inhibition of protein phosphatase-1/2A and calpain rescues nerve growth factor-differentiated PC12 cells from oxygen-glucose deprivation-induced cell death. 1638 61

In view of the known involvement of oxidative stress and calcineurin (Ca(2+)-calmodulin dependent protein phosphatase) in beta-Adrenergic stimulated events, we examined the influence of eugenol (an antioxidant generally regarded as safe by the Food and Agricultural Organization of the United Nations) on isoproterenol-induced apoptosis in neonatal cardiomyocytes. In comparison to unstimulated controls, cardiomyocytes stimulated with 50 microM isoproterenol for 48 h demonstrated (a) increased intracellular Ca(2+) levels (b) oxidative stress involving enhanced reactive oxygen species, decreased GSH/GSSG ratio, enhanced lipid peroxidation, increased activities of superoxide dismutase and glutathione peroxidase (c) apoptosis, evidenced by increased number of annexin V/TUNEL positive cells, enhanced membrane fluidity, decreased mitochondrial membrane potential, increased activities of caspase 3 and 9 along with (d) increased calcineurin activity. Pre-incubation of cardiomyocytes with 100 microM eugenol for 1 h, followed by isoproterenol treatment for 48 h, led to reversal of enhanced intracellular Ca(2+) levels, oxidative stress, calcineurin activation and apoptosis caused by isoproterenol. In addition, similar treatment of cardiomyocytes with 10 nM FK506, a calcineurin inhibitor, could also attenuate isoproterenol-induced apoptosis. These results indicate the beneficial effects of eugenol in preventing cardiomyocyte apoptosis.
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PMID:Interrelations between oxidative stress and calcineurin in the attenuation of cardiac apoptosis by eugenol. 1644 93

Calpain activation has been implicated in the pathogenesis of Alzheimer's disease. Okadaic acid, a protein phosphatase-2A inhibitor, has been used in Alzheimer's disease research models to increase tau phosphorylation and induce neuronal death. We previously reported that okadaic acid induced predominant activation of caspase-3 in immature neurons, but less activation in mature neurons. We found here that, in okadaic-acid-treated mature neurons, levels of an inactive form of m-calpain decreased and levels of calpain-cleaved spectrin and synapsin-I fragments increased, suggestive of calpain activation. Pretreatment with calpain inhibitor decreased lactate dehydrogenase release by 20% and increased average dendritic branch length by 50% compared with neurons treated with okadaic acid alone. These findings suggest that calpain is activated during okadaic-acid-induced neurodegeneration and calpain inhibition can be protective against it.
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PMID:Calpain activation in okadaic-acid-induced neurodegeneration. 1664 70

Glucocorticoid excess induces hyperglycemia, which may result in diabetes. The present experiments explored whether glucocorticoids trigger apoptosis in insulin-secreting cells. Treatment of mouse beta-cells or INS-1 cells with the glucocorticoid dexamethasone (0.1 micromol/l) over 4 days in cell culture increased the number of fractionated nuclei from 2 to 7 and 14%, respectively, an effect that was reversed by the glucocorticoid receptor antagonist RU486 (1 micromol/l). In INS-1 cells, dexamethasone increased the number of transferase-mediated dUTP nick-end labeling-staining positive cells, caspase-3 activity, and poly-(ADP-) ribose polymerase protein cleavage; decreased Bcl-2 transcript and protein abundance; dephosphorylated the proapoptotic protein of the Bcl-2 family (BAD) at serine155; and depolarized mitochondria. Dexamethasone increased PP-2B (calcineurin) activity, an effect abrogated by FK506. FK506 (0.1 micromol/l) and another calcineurin inhibitor, deltamethrin (1 micromol/l), attenuated dexamethasone-induced cell death. The stable glucagon-like peptide 1 analog, exendin-4 (10 nmol/l), inhibited dexamethasone-induced apoptosis in mouse beta-cells and INS-1 cells. The protective effect of exendin-4 was mimicked by forskolin (10 micromol/l) but not mimicked by guanine nucleotide exchange factor with the specific agonist 8CPT-Me-cAMP (50 micromol/l). Exendin-4 did not protect against cell death in the presence of cAMP-dependent protein kinase (PKA) inhibition by H89 (10 micromol/l) or KT5720 (5 micromol/l). In conclusion, glucocorticoid-induced apoptosis in insulin-secreting cells is accompanied by a downregulation of Bcl-2, activation of calcineurin with subsequent dephosphorylation of BAD, and mitochondrial depolarization. Exendin-4 protects against glucocorticoid-induced apoptosis, an effect mimicked by forskolin and reversed by PKA inhibitors.
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PMID:Dexamethasone induces cell death in insulin-secreting cells, an effect reversed by exendin-4. 1664 95

Serine/threonine phosphatase regulation of phosphorylation-mediated intracellular signaling controls a number of important processes in mammalian cells. In this study, we show that constitutively active protein phosphatase 2A (PP2A), which is a serine/threonine phosphatase, is essential for T leukemia cell survival. Jurkat and CCRF-CEM T leukemia cells treated with the PP2A-selective inhibitor okadaic acid (OA) showed a dose- and time-dependent induction of apoptosis, as indicated by loss of mitochondrial transmembrane potential (delta psi(m)), cleavage-induced activation of caspase-3, -8, and -9, and DNA fragmentation. In addition, caspase-8 or caspase-9 inhibition with z-IETD-fmk or z-LEHD-fmk, respectively, largely prevented OA-induced apoptosis. Although OA treatment did not affect constitutive Bcl-2 expression, overexpression of Bcl-2 prevented both OA-induced DNA fragmentation and dissipation of delta psi(m). Furthermore, inhibition of caspase-3, -8, or -9 partially protected against OA-induced loss of delta psi(m). In addition, caspase-9 and caspase-3 inhibition largely prevented procaspase-3 and procaspase-8 cleavage, respectively, while caspase-8 inhibition partially interfered with procaspase-9 cleavage in OA-treated T leukemia cells. Thus, PP2A inhibition triggered the intrinsic pathway of apoptosis, which was enhanced by a mitochondrial feedback amplification loop. PP2A has also been implicated in the regulation of p38 mitogen-activated protein kinase (MAPK). Co-immunoprecipitation analysis revealed a physical association between the catalytic subunit of PP2A and p38 MAPK in T leukemia cells. Moreover, OA treatment caused p38 MAPK to be phosphorylated in a dose- and time-dependent fashion, indicating that PP2A prevented p38 MAPK activation. Although p38 MAPK activation usually promotes apoptosis, pharmacologic inhibition of p38 MAPK exacerbated OA-induced DNA fragmentation and loss of delta psi(m) in T leukemia cells, suggesting that, in this instance, the p38 MAPK signaling pathway promoted cell survival. Collectively, these findings indicate that PP2A and p38 MAPK have coordinate effects on signaling pathways that regulate the survival of T leukemia cells.
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PMID:Apoptosis induced by protein phosphatase 2A (PP2A) inhibition in T leukemia cells is negatively regulated by PP2A-associated p38 mitogen-activated protein kinase. 1684 42

Reactive oxygen species are believed to be the central mediators of beta-cell destruction that leads to type 1 and 2 diabetes, and calcium has been reported to be an important mediator of beta cell death. In the present study, the authors investigated whether Ca(2+) plays a role in hydrogen peroxide (H(2)O(2))-induced MIN6N8a mouse beta cell death. Treatment with low concentration H(2)O(2) (50 microM) was found to be sufficient to reduce MIN6N8a cell viability by 55%, largely via apoptosis. However, this H(2)O(2)-induced cell death was near completely blocked by pretreatment with BAPTA/AM (5 microM), a chelator of intracellular Ca(2+). Moreover, the intracellular calcium store channel blockers, such as, xestospongin c and ryanodine, significant protected cells from 50 microM H(2)O(2)-induced cell death and under extracellular Ca(2+)-free conditions, 50 microM H(2)O(2) elicited transient [Ca(2+)](i) increases. In addition, pharmacologic inhibitors of calpain, calcineurin, and calcium/calmodulin-dependent protein kinase II were found to have a protective effect on H(2)O(2)-induced death. Moreover, H(2)O(2)-induced apoptotic signals, such as c-JUN N-terminal kinase activation, cytochrome c release, caspase 3 activation, and poly (ADP-ribose) polymerase cleavage were all down-regulated by the intracellular Ca(2+) chelation. These findings show that [Ca(2+)](i) elevation, possibly due to release from intracellular calcium stores and the subsequent activation of Ca(2+)-mediated apoptotic signals, critically mediates low concentration H(2)O(2)-induced MIN6N8a cell death. These findings suggest that a breakdown of calcium homeostasis by low level of reactive oxygen species may be involved in beta cell destruction during diabetes development.
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PMID:Involvement of calcium-mediated apoptotic signals in H2O2-induced MIN6N8a cell death. 1693 99

Sulfur mustard (SM) causes blisters in the skin through a series of cellular changes that we are beginning to identify. We earlier demonstrated that SM toxicity is the result of induction of both death receptor and mitochondrial pathways of apoptosis in human keratinocytes (KC). Because of its importance in apoptosis in the skin, we tested whether calmodulin (CaM) mediates the mitochondrial apoptotic pathway induced by SM. Of the three human CaM genes, the predominant form expressed in KC was CaM1. RT-PCR and immunoblot analysis revealed upregulation of CaM expression following SM treatment. To delineate the potential role of CaM1 in the regulation of SM-induced apoptosis, retroviral vectors expressing CaM1 RNA in the antisense (AS) orientation were used to transduce and derive stable CaM1 AS cells, which were then exposed to SM and subjected to immunoblot analysis for expression of apoptotic markers. Proteolytic activation of executioner caspases-3, -6, -7, and the upstream caspase-9, as well as caspase-mediated PARP cleavage were markedly inhibited by CaM1 AS expression. CaM1 AS depletion attenuated SM-induced, but not Fas-induced, proteolytic processing and activation of caspase-3. Whereas control KC exhibited a marked increase in apoptotic nuclear fragmentation after SM, CaM1 AS cells exhibited normal nuclear morphology up to 48h after SM, indicating that suppression of apoptosis in CaM1 AS cells increases survival and does not shift to a necrotic death. CaM has been shown to activate the phosphatase calcineurin, which can induce apoptosis by Bad dephosphorylation. Interestingly, whereas SM-treated CaM1-depleted KC expressed the phosphorylated non-apoptotic sequestered form of Bad, Bad was present in the hypophosphorylated apoptotic form in SM-exposed control KC. To determine if pharmacological CaM inhibitors could attenuate SM-induced apoptosis via Bad dephosphorylation, KC were pretreated with the CaM-specific antagonist W-13 or its less active structural analogue W-12. Following SM exposure, KC exhibited Bad dephosphorylation, which was inhibited in the presence of W-13, but not with W-12. Consequently, W-13 but not W-12 markedly suppressed SM-induced proteolytic processing and activation of caspase-3, as well as apoptotic nuclear fragmentation. Finally, while the CaM antagonist W-13 and the calcineurin inhibitor cyclosporin A attenuated SM-induced caspase-3 activation, inhibitors for CaM-dependent protein kinase II (KN62 and KN93) did not. These results indicate that CaM, calcineurin, and Bad also play a role in SM-induced apoptosis, and may therefore be targets for therapeutic intervention to reduce SM injury.
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PMID:Calmodulin mediates sulfur mustard toxicity in human keratinocytes. 1693 4

Visceral leishmaniasis (VL) produced in BALB/c mice through intracardial administration of Leishmania donovani amastigotes was accompanied by hepatosplenomegaly with high organ parasite load and lymphadenopathy when followed up to 4-months or so. To elucidate the mechanism of immunosuppression associated with VL, we report here progressive impairment of the proliferative response of lymph node cells (lymphocytes) from infected animals (I-LNC) to in vitro stimulation with the combination of phorbol 12-myristate 13-acetate (PMA) and ionomycin (Io) that could be related to the downregulation of PKC and MAP kinase (ERK 1/2) activation process. Further, pretreatment of I-LNC with the protein phosphatase inhibitor okadaic acid (OA), but not with calyculin A or sodium orthovanadate, significantly restored their proliferative response as well as PMA-induced activation of PKC. A population of LNC (primarily T-lymphocytes) from chronically infected animals was shown to undergo apoptosis, the number of which increased considerably following PMA+ Io stimulation. The apoptotic pathway, which was followed through binding of cells to Annexin V, activation of caspase-3 and fragmentation of DNA, involved destabilization of mitochondria, probably as a result of downregulation of PKC and Bcl-2. Interestingly, prior incubation of I-LNC with OA reversed the state of cell cycle arrest (anergy) and apoptosis through progression of cells from G0/G1 to S and G2/M phases with transcriptional activation of IL-2 and IL-2R genes. Our results suggest that the cellular (immune) dysfunction in VL could be attributed to dephosphorylation of key molecules in the T-lymphocyte signaling pathway by Ser/Thr phosphatase leading to their inactivation.
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PMID:Lymph node cells from BALB/c mice with chronic visceral leishmaniasis exhibiting cellular anergy and apoptosis: involvement of Ser/Thr phosphatase. 1701 55

The present study focused on mechanisms involved in the anti-apoptotic effect of cyclosporin A (CsA) towards ischemic injured astrocytes in vitro [under combined oxygen glucose deprivation (OGD)]. We investigated whether this action might be mediated through activation of extracellular signal regulated kinases 1 and 2 (Erk1/2) or attenuation of calcineurin (CaN) by immunosuppressant in ischemic astrocytes. Additionally, the influence of CsA on phosphorylation of Akt kinase was determined. After 21 days of in vitro culture, astrocytes were subjected to OGD (for 8 h) and CsA (0.25-10 microM); 0.25 microM CsA distinctly stimulated the Erk1/2 pathway in astrocytes exposed to OGD. This protective effect of CsA was strongly associated with CaN inhibition, increased expression of anti-apoptotic factors such as Bcl-X(L) and NF-kappaB, as well as suppression of caspase-3 activity. Maximum p-Akt kinase expression was observed following treatment with 1 microM CsA. Finally, we also demonstrated that the beneficial effect of CsA at a concentration of 10 microM is related mainly to strong CaN inhibition. The results obtained suggest that, depending on the concentration used, CsA might act as a protective agent towards ischemia-injured astroglial cells through alternative intracellular pathways associated with increased p-Erk1/2 and p-Akt expression or CaN inactivation.
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PMID:Calcineurin and Erk1/2-signaling pathways are involved in the antiapoptotic effect of cyclosporin A on astrocytes exposed to simulated ischemia in vitro. 1702 52

Short chain fatty acids including butyrate exhibit wide variety of biological effects towards cell growth, morphology and gene expression. In this report, we study the mechanism by which butyrate (BuA) modulates the expression of protein phosphatase when treated to the cells. As a model system, we used Ehrlich Ascites Tumor (EAT) cells in which BuA-treatment induces expression of a protein phosphatase enzyme. Subsequently, BuA-induced protein phosphatase has been biochemically purified and characterized. Further, pretreatment of caspase-3 inhibitor abolished the activity of BuA-induced protein phosphatase indicating the involvement of caspase-3 in the activation of BuA-induced protein phosphatase. In addition, the relationship between BuA-induced protein phosphatase and apoptosis has been verified. Activation of endonuclease-II has been shown in BuA-treated EAT cells and that activity was completely inhibited by sodium orthovanadate, a tyrosine phosphatase inhibitor suggesting that endonuclease-II may serve as a possible down-stream target for BuA-induced protein phosphatase. Together, the data suggest that activation of protein phosphatase may be an early and essential step in BuA-mediated apoptotic signaling pathway in EAT cells.
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PMID:Purification and characterization of butyrate-induced protein phosphatase involved in apoptosis of Ehrlich ascites tumor cells. 1702 93


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