Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Hyperphosphorylated tau is the major protein subunit of neurofibrillary tangles in Alzheimer's disease (AD) and related tauopathies. It is not understood, however, why the neurofibrillary tangle-containing neurons seen in the AD brains do not die of apoptosis but rather degeneration even though they are constantly awash in a proapoptotic environment. Here, we show that cells overexpressing tau exhibit marked resistance to apoptosis induced by various apoptotic stimuli, which also causes correlated tau hyperphosphorylation and glycogen synthase kinase 3 (GSK-3) activation. GSK-3 overexpression did not potentiate apoptotic stimulus-induced cell apoptosis in the presence of high levels of tau. The resistance of neuronal cells bearing hyperphosphorylated tau to apoptosis was also evident by the inverse staining pattern of PHF-1-positive tau and activated caspase-3 or fragmented nuclei in cells and the brains of rats or tau-transgenic mice. Tau hyperphosphorylation was accompanied by decreases in beta-catenin phosphorylation and increases in nuclear translocation of beta-catenin. Reduced levels of beta-catenin antagonized the antiapoptotic effect of tau, whereas overexpressing beta-catenin conferred resistance to apoptosis. These results reveal an antiapoptotic function of tau hyperphosphorylation, which likely inhibits competitively phosphorylation of beta-catenin by GSK-3beta and hence facilitates the function of beta-catenin. Our findings suggest that tau phosphorylation may lead the neurons to escape from an acute apoptotic death, implying the essence of neurodegeneration seen in the AD brains and related tauopathies.
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PMID:Phosphorylation of tau antagonizes apoptosis by stabilizing beta-catenin, a mechanism involved in Alzheimer's neurodegeneration. 1736 Jun 87

Astrocyte apoptosis occurs in acute and chronic pathological processes at the central nervous system and the prevention of astrocyte death may represent an efficacious intervention in protecting neurons against degeneration. Our research shows that rat astrocyte exposure to 100 nM staurosporine for 3h caused apoptotic death accompanied by caspase-3, p38 mitogen-ed protein kinase (MAPK) and glycogen synthase kinase-3beta (GSK3beta) activation. N(6)-chlorocyclopentyladenosine (CCPA, 2.5-75 nM), a selective agonist of A(1) adenosine receptors, added to the cultures 1h prior to staurosporine, induced a dose-dependent anti-apoptotic effect, which was inhibited by the A(1) receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine. CCPA also caused a dose- and time-dependent phosphorylation/activation of Akt, a downstream effector of cell survival promoting phosphatidylinositol 3-kinase (PI3K) pathway, which in turn led to inhibition of staurosporine-induced GSK3beta and p38 MAPK activity. Accordingly, the anti-apoptotic effect of CCPA was abolished by culture pre-treatment with LY294002, a selective PI3K inhibitor, pointing out the prevailing role played by PI3K pathway in the protective effect exerted by A(1) receptor activation. Since an abnormal p38 and GSK3beta activity is implicated in acute (stroke) and chronic (Alzheimer's disease) neurodegenerative diseases, the results of the present study provide a hint to better understand adenosine relevance in these disorders.
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PMID:Staurosporine-induced apoptosis in astrocytes is prevented by A1 adenosine receptor activation. 1740 Mar 82

Calcium ion is essential for cellular functions including signal transduction. Uncontrolled calcium stress has been linked causally to a variety of neurodegenerative diseases. Thapsigargin, which inhibits Ca(2+)-ATPase in the endoplasmic reticulum (ER) and blocks the sequestration of calcium by the ER, induced apoptotic cell death (chromatin condensation and nuclear fragmentation) accompanied by GRP78 protein expression and caspase-3 activation in rat fetal cortical neurons (days in vitro 9-10). Blockade of N-methyl-D-aspartate (NMDA) receptors with NMDA antagonists induced apoptosis without GRP78 protein expression. Apoptosis accompanied both caspase-9 and caspase-3 activation. We then examined whether GSK-3 is involved in thapsigargin-induced cell death by using GSK-3 inhibitors. We assayed the effects of selective GSK-3 inhibitors, SB216763, alsterpaullone and 1-azakenpaullone, on thapsigargin-induced apoptosis. These inhibitors completely protected cells from thapsigargin-induced apoptosis. In addition, GSK-3 inhibitors inhibited caspase-9 and caspase-3 activation accompanied by thapsigargin-induced apoptosis. These results suggest that thapsigargin induces caspase-dependent apoptosis mediated through GSK-3beta activation in rat cortical neurons.
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PMID:Caspase-dependent apoptosis induced by thapsigargin was prevented by glycogen synthase kinase-3 inhibitors in cultured rat cortical neurons. 1740 51

Apoptosis is a contributing cause of dopaminergic neuron loss in Parkinson disease. Recent work has shown that erythropoietin (EPO) offers protection against apoptosis in a wide variety of tissues. We demonstrate that exposure of PC12 cells to 1-methyl-4-phenylpyridinium ion (MPP(+)) with recombinant human EPO, significantly decreased apoptosis as measured by TUNEL and caspase-3 activity when compared to MPP(+) treatment alone. EPO induced sustained phosphorylation of Akt and its substrate, GSK-3beta, reduced caspase-3 activities in PC12 cells. The anti-apoptotic effect of EPO was abrogated by co-treatment with LY294002, the specific blocker of phosphatidylinositol 3-kinase (PI3K). The effects of EPO on GSK-3beta and caspase-3 activities were also blocked by LY294002. LiCl, the inhibitor of GSK-3beta, downregulated the caspase-3 activity and blocked the apoptosis induced by MPP(+). Finally, we determined that EPO transiently activated the ERK signaling pathway, but PD98059, a specific inhibitor of ERK, does not alter the survival effect of EPO in this model system. Thus, these findings indicate that EPO protects against apoptosis in PC12 cells exposed to MPP(+), through the Akt/GSK-3beta/caspase-3 signaling pathway, but the ERK pathway is not involved in the EPO-dependent survival enhancing effect in this model system.
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PMID:Erythropoietin prevents PC12 cells from 1-methyl-4-phenylpyridinium ion-induced apoptosis via the Akt/GSK-3beta/caspase-3 mediated signaling pathway. 1750 73

N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine (PCP) can induce positive and negative symptoms of schizophrenia in humans and related effects in rodents. PCP treatment of developing rats induces apoptotic neurodegeneration and behavioral deficits later in life that mimic some symptoms of schizophrenia. The precise mechanism of PCP-induced neural degeneration is unknown. This study used selective antagonists, siRNA, and Western analysis to investigate the role of the Akt-glycogen synthase kinase-3beta (GSK-3beta) pathway in PCP-induced neuronal apoptosis in both neuronal culture and postnatal day 7 rats. PCP administration in vivo and in vitro reduced the phosphorylation of Akt Ser427 and GSK-3beta Ser9, decreasing Akt activity and increasing GSK-3beta activity. The alteration of Akt-GSK-3beta signaling parallels the temporal profile of caspase-3 activation by PCP. Reducing GSK-3beta activity by application of selective inhibitors or depletion of GSK-3beta by siRNA attenuates caspase-3 activity and blocks PCP-induced neurotoxicity. Moreover, increasing synaptic strength by either activation of L-type calcium channels with BAY K8644 or potentiation of synaptic NMDA receptors with either a low concentration of NMDA or bicuculline plus 4-aminopyridine completely blocks PCP-induced cell death by increasing Akt phosphorylation. These neuroprotective effects are associated with activation of phosphoinositide-3-kinase-Akt signaling, and to a lesser extent, the MAPK signaling pathway. Overall, these data suggest that PCP-induced hypofunction of synaptic NMDA receptors impairs the Akt-GSK-3beta cascade, which is necessary for neuronal survival during development, and that interference with this cascade by PCP or natural factors may contribute to neural pathologies, perhaps including schizophrenia.
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PMID:The role of Akt-GSK-3beta signaling and synaptic strength in phencyclidine-induced neurodegeneration. 1763 6

High mobility group box 1 (HMGB1) is a chromatin protein that acts as an immunomodulatory cytokine upon active release from myeloid cells. HMGB1 is also an alarmin, an endogenous molecule released by dying cells that acts to initiate tissue repair. We have previously reported that osteoclasts and osteoblasts release HMGB1 and release by the latter is regulated by parathyroid hormone (PTH), an agent of bone remodeling. A recent study suggests that HMGB1 acts as a chemotactic agent to osteoclasts and osteoblasts during endochondral ossification. To explore the potential impact of HMGB1 in the bone microenvironment and its mechanism of release by osseous cells, we characterized the effects of recombinant protein (rHMGB1) on multiple murine bone cell preparations that together exhibit the various cell phenotypes present in bone. We also inquired whether apoptotic bone cells release HMGB1. rHMGB1 enhanced the RANKL/OPG steady state mRNA ratio and dramatically augmented the release of tumor necrosis factor-alpha (TNFalpha) and interleukin-6 (IL6) in osteoblastogenic bone marrow stromal cell (BMSC) cultures but not in the calvarial-derived MC3T3-E1 cells. Interestingly, rHMGB1 promoted GSK-3beta phosphorylation in MC3T3-E1 cells but not in BMSCs. Apoptotic bone cells released HMGB1, including MLO-Y4 osteocyte-like cells. MLO-Y4 release of HMGB1 was coincident with caspase-3 cleavage. Furthermore, the anti-apoptotic action of PTH on MC3T3-E1 cells correlated with the observed decrease in HMGB1 release. Our data suggest that apoptotic bone cells release HMGB1, that within the marrow HMGB1 is a bone resorption signal, and that intramembraneous and endochondral osteoblasts exhibit differential responses to this cytokine.
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PMID:HMGB1 is a bone-active cytokine. 1778 58

Chronic administration of glucagon-like peptide-2 (GLP-2) induces intestinal growth and crypt cell proliferation through an indirect mechanism requiring IGF-I. However, the intracellular pathways through which IGF-I mediates GLP-2-induced epithelial tropic signaling remain undefined. Because beta-catenin and Akt are important regulators of crypt cell proliferation, we hypothesized that GLP-2 activates these signaling pathways through an IGF-I-dependent mechanism. In this study, fasted mice were administered Gly(2)-GLP-2 or LR(3)-IGF-I (positive control) for 0.5-4 h. Nuclear translocation of beta-catenin in non-Paneth crypt cells was assessed by immunohistochemistry and expression of its downstream proliferative markers, c-myc and Sox9, by quantitative RT-PCR. Akt phosphorylation and activation of its targets, glycogen synthase kinase-3beta and caspase-3, were determined by Western blot. IGF-I receptor (IGF-IR) and IGF-I signaling were blocked by preadministration of NVP-AEW541 and through the use of IGF-I knockout mice, respectively. We found that GLP-2 increased beta-catenin nuclear translocation in non-Paneth crypt cells by 72 +/- 17% (P < 0.05) and increased mucosal c-myc and Sox9 mRNA expression by 90 +/- 20 and 376 +/- 170%, respectively (P < 0.05-0.01), with similar results observed with IGF-I. This effect of GLP-2 was prevented by blocking the IGF-IR as well as ablation of IGF-I signaling. GLP-2 also produced a time- and dose-dependent activation of Akt in the intestinal mucosa (P < 0.01), most notably in the epithelium. This action was reduced by IGF-IR inhibition but not IGF-I knockout. We concluded that acute administration of GLP-2 activates beta-catenin and proliferative signaling in non-Paneth murine intestinal crypt cells as well as Akt signaling in the mucosa. However, IGF-I is required only for the GLP-2-induced alterations in beta-catenin.
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PMID:Glucagon-like peptide-2 activates beta-catenin signaling in the mouse intestinal crypt: role of insulin-like growth factor-I. 1788 45

Doxorubicin (DOX) is an effective antineoplastic agent whose use has been limited by its cardiotoxic side effects. Recent studies have established that erythropoietin (EPO), a cytokine essential for red blood cell production, protects against ischemic injury in the heart and other organs. The purpose of this study was to assess whether EPO protects the heart against cardiotoxicity induced by DOX. We found that DOX-induced apoptosis and impaired heart function in mice were largely prevented by EPO administration. To investigate the mechanism of protection by EPO, cultured neonatal mouse ventricular myocytes were treated with EPO at therapeutic levels (i.e., 1 U/ml), before application of DOX (0.1-1.0 microM). EPO protected against DOX-induced cardiomyocyte death (by approximately 50%) and apoptosis assessed by annexin-V labeling, DNA fragmentation, and caspase-3 activity. DOX-mediated increases in reactive oxygen species, which trigger cardiotoxicity, were also reversed by preconditioning with EPO. These functional effects of EPO correlated with increased Akt/protein kinase B ( approximately 2-fold) and glycogen synthase kinase 3 (GSK-3; approximately 1.3-fold) phosphorylations, suggesting protection by EPO was mediated by phosphatidylinositol 3-kinase activation. Indeed, preventing Akt and GSK-3beta phosphorylations by phosphatidylinositol 3-kinase (PI3K) inhibition abolished protection by EPO against cardiomyocyte loss, apoptosis, and oxidative stress. Thus, pretreatment with therapeutic levels of EPO can protect the myocardium against DOX-induced impaired heart function and cardiomyocyte apoptosis by activating PI3K-Akt cell survival pathways.
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PMID:Erythropoietin protects against doxorubicin-induced cardiomyopathy via a phosphatidylinositol 3-kinase-dependent pathway. 1792 71

Erythropoietin (EPO) prevents neuronal cell death through the activation of cell survival signals and the inhibition of apoptotic signals in models of neurodegenerative diseases. Here we investigated the neuroprotective effect of EPO in ketamine-induced neurotoxicity in primary cortical neurons. EPO in combination with ketamine greatly increased the cell viability and reduced the number of TUNEL-positive cells. To elucidate a possible mechanism by which EPO exerts its neuroprotective effect, we investigated the phosphoinositide3-kinase pathway using LY294002. The neuroprotection of EPO was prevented by LY294002. Immunoblotting revealed that EPO induced the phosphorylation/activation of Akt and phosphorylation/inactivation of glycogen synthase kinase-3beta (GSK-3beta). Moreover, the caspase-3-like activity was increased by addition of ketamine, and decreased by administration of ketamine with EPO. Decreased caspase-3-like activity by administration of ketamine with EPO was restored by LY294002. Our results suggest that PI3K/Akt and GSK-3beta pathway are involved in the neuroprotective effect of EPO.
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PMID:Protective effect of erythropoietin against ketamine-induced apoptosis in cultured rat cortical neurons: involvement of PI3K/Akt and GSK-3 beta pathway. 1795 4

The phosphatidylinositol-3-kinase (PI3-K) pathway has been suggested to play a pivotal role in neuronal survival. Although PI3-K has been recently identified as a neuroprotectant, there are no reports regarding the effect of a direct PI3-K activator on Abeta-induced neurotoxicity. We investigated whether direct PI3-K activation prevents Abeta-induced neurotoxicity. To evaluate the effect of Abeta on neuronal cells, we treated primary cultured cortical neurons with several doses of Abeta for 72 h. To investigate the protective effect that PI3-K activation has on Abeta-induced neurotoxicity, cells were simultaneously treated with several doses of a PI3-K activator for 72 h. An MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, trypan blue staining, and DAPI staining showed that Abeta decreased neuronal cell viability in a concentration-dependent manner and also that PI3-K activation effectively prevented Abeta-induced neuronal cell death. Abeta significantly decreased survival signals, including phosphorylated Akt, glycogen synthase kinase-3beta, and heat shock transcription factor-1. Abeta also increased death signals, such as phosphorylated tau (pThr231) and activated caspase-3. Treatment with a PI3-K activator restored the survival signals and inhibited the death signals. These results suggest that the neurotoxic effect of Abeta can be partially prevented by PI3-K activation.
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PMID:Phosphatidylinositol-3-kinase activation blocks amyloid beta-induced neurotoxicity. 1798 Apr 76


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