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: EC:3.4.22.60 (caspase-7)
920 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alterations in Ca(2+) homeostasis and accumulation of unfolded proteins in the endoplasmic reticulum (ER) lead to an ER stress response. Prolonged ER stress may lead to cell death. Glucose-regulated protein (GRP) 78 (Bip) is an ER lumen protein whose expression is induced during ER stress. GRP78 is involved in polypeptide translocation across the ER membrane, and also acts as an apoptotic regulator by protecting the host cell against ER stress-induced cell death, although the mechanism by which GRP78 exerts its cytoprotective effect is not understood. The present study was carried out to determine whether one of the mechanisms of cell death inhibition by GRP78 involves inhibition of caspase activation. Our studies indicate that treatment of cells with ER stress inducers causes GRP78 to redistribute from the ER lumen with subpopulations existing in the cytosol and as an ER transmembrane protein. GRP78 inhibits cytochrome c-mediated caspase activation in a cell-free system, and expression of GRP78 blocks both caspase activation and caspase-mediated cell death. GRP78 forms a complex with caspase-7 and -12 and prevents release of caspase-12 from the ER. Addition of (d)ATP dissociates this complex and may facilitate movement of caspase-12 into the cytoplasm to set in motion the cytosolic component of the ER stress-induced apoptotic cascade. These results define a novel protective role for GRP78 in preventing ER stress-induced cell death.
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PMID:Coupling endoplasmic reticulum stress to the cell death program: role of the ER chaperone GRP78. 1194 37

Caspase-3 is a major cell death effector protease in the adult and neonatal nervous system. We found a greater number and higher density of cells in the cortex of caspase-3(-/-) adult mice, consistent with a defect in developmental cell death. Caspase-3(-/-) mice were also more resistant to ischemic stress both in vivo and in vitro. After 2 h of ischemia and 48 h of reperfusion, cortical infarct volume was reduced by 55%, and the density of terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling-positive cells was decreased by 36% compared with wild type. When subjected to oxygen-glucose deprivation (2 h), cortical neurons cultured from mice deficient in caspase-3 expression were also more resistant to cell death by 59%. Mutant brains showed caspase-specific poly(ADP-ribose) polymerase cleavage product (85-kDa fragment) in vivo and in vitro, suggesting redundant mechanisms and persistence of caspase-mediated cell death. In the present study, we found that caspase-8 mediated poly(ADP-ribose) polymerase cleavage in caspase-3(-/-) neurons in vivo and in vitro. In addition, mutant neurons showed no evidence of compensatory activation by caspase-6 or caspase-7 after ischemia. Taken together, these data extend the pharmacological evidence supporting an important role for caspase-3 and caspase-8 as cell death mediators in mammalian cortex and indicate the potential advantages of targeting more than a single caspase family member to treat ischemic cell injury.
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PMID:Caspase activation and neuroprotection in caspase-3- deficient mice after in vivo cerebral ischemia and in vitro oxygen glucose deprivation. 1241 17

A large number of correlative studies have established that the activation of the unfolded protein response (UPR) alters the cell's sensitivity to chemotherapeutic agents. Although the induction of the glucose-regulated proteins (GRPs) is commonly used as an indicator for the UPR, the direct role of the GRPs in conferring resistance to DNA damaging agents has not been proven. We report here that without the use of endoplasmic reticulum (ER) stress inducers, specific overexpression of GRP78 results in reduced apoptosis and higher colony survival when challenged with topoisomerase II inhibitors, etoposide and doxorubicin, and topoisomerase I inhibitor, camptothecin. While investigating the mechanism for the GRP78 protective effect against etoposide-induced cell death, we discovered that in contrast to the UPR, GRP78 overexpression does not result in G1 arrest or depletion of topoisomerase II. Caspase-7, an executor caspase that is associated with the ER, is activated by etoposide. We show here that specific expression of GRP78 blocks caspase-7 activation by etoposide both in vivo and in vitro, and this effect can be reversed by addition of dATP in a cell-free system. Recently, it was reported that ectopically expressed GRP78 and caspases-7 and -12 form a complex, thus coupling ER stress to the cell death program. However, the mechanism of how GRP78, a presumably ER lumen protein, can regulate cytosolic effectors of apoptosis is not known. Here we provide evidence that a subpopulation of GRP78 can exist as an ER transmembrane protein, as well as co-localize with caspase-7, as confirmed by fluorescence microscopy. Co-immunoprecipitation studies further reveal endogenous GRP78 constitutively associates with procaspase-7 but not with procaspase-3. Lastly, a GRP78 mutant deleted of its ATP binding domain fails to bind procaspase-7 and loses its protective effect against etoposide-induced apoptosis.
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PMID:Endoplasmic reticulum chaperone protein GRP78 protects cells from apoptosis induced by topoisomerase inhibitors: role of ATP binding site in suppression of caspase-7 activation. 1266 8

After birth, constriction of the full-term ductus arteriosus produces ischemic hypoxia, caspase activation, DNA fragmentation (>70% of cell nuclei are positive by the terminal deoxynucleotidyl transferase nick-end labeling [TUNEL] technique), and permanent ductus closure. In contrast, the preterm ductus frequently fails to develop these changes. We used the TUNEL technique to examine rings of fetal ductus arteriosus (incubated for 24 h at different oxygen and glucose concentrations) to determine the roles of 1) constriction and shortening, 2) hypoxia, and 3) hypoglycemia in producing cell death. Under controlled conditions, late-gestation ductus rings had a low rate of TUNEL-positive staining (0.6 +/- 0.9%) that did not change during muscle shortening. Although hypoxia (6.9 +/- 3.5%) and hypoglycemia (2.4 +/- 1.9%) increased the incidence of TUNEL-positive staining, only the combination of hypoxia-plus-hypoglycemia increased the incidence to the range found in vivo (83 +/- 9.5%). The combination of hypoxia-plus-hypoglycemia was associated with an oligonucleosomal pattern of DNA fragmentation. Under the same experimental conditions, the preterm ductus was capable of developing a similar degree of TUNEL-positive staining as found at term. Although caspase-3 and caspase-7 were activated in rings exposed to hypoxia-plus-hypoglycemia, a nonselective caspase inhibitor, Z-VAD.FMK (which inhibited caspase-3 and caspase-7 cleavage in the rings), did not diminish the degree of TUNEL-positive staining. We hypothesize that the preterm ductus is capable of developing an extensive degree of cell death, if it can develop the same degree of hypoxia and hypoglycemia found in the full-term newborn ductus. We also hypothesize that cell death in the ductus wall may involve pathways that are not dependent on caspase-3 or -7 activation.
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PMID:Effects of hypoxia, hypoglycemia, and muscle shortening on cell death in the sheep ductus arteriosus. 1273 84

Several evidences suggest that cell death after cerebral ischemia involves both necrosis and apoptosis. However, it is still unknown which is the relative contribution of both types of cell death. Exposing rat cortical cultures to oxygen-glucose deprivation (OGD), we show the simultaneous presence of necrotic and apoptotic cells. The relative contribution of necrosis and apoptosis was dependent on the duration of the OGD. OGD-mediated apoptotic cell death is caspase-dependent because the addition of a pan-caspase inhibitor specifically blocked the apoptotic component of the OGD-mediated cell death. Moreover, we observed the activation of caspase-3, -7, and -9 after OGD in neurons and microglial cells. No activation of these caspases was observed in GFAP positive cells. Our results also show that calpain is related to OGD-mediated proteolysis of caspase-3 and -9 but not of caspase-7. These data suggest that different pathways could be involved in OGD-mediated caspase activation.
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PMID:Contribution of caspase-mediated apoptosis to the cell death caused by oxygen-glucose deprivation in cortical cell cultures. 1613 64

The endoplasmic reticulum (ER) is the principal organelle for the biosynthesis of proteins, steroids and many lipids, and is highly sensitive to alterations in its environment. Perturbation of Ca(2+) homeostasis, elevated secretory protein synthesis, deprivation of glucose or other sugars, altered glycosylation and/or the accumulation of misfolded proteins may all result in ER stress, and prolonged ER stress triggers cell death. Studies from multiple laboratories have identified the roles of several ER stress-induced cell-death modulators and effectors through the use of biochemical, pharmacological and genetic tools. In the present work, we describe the role of p23, a small chaperone protein, in preventing ER stress-induced cell death. p23 is a highly conserved chaperone protein that modulates HSP90 activity and is also a component of the steroid receptors. p23 is cleaved during ER stress-induced cell death; this cleavage, which occurs close to the carboxy-terminus, requires caspase-3 and/or caspase-7, but not caspase-8. Blockage of the caspase cleavage site of p23 was associated with decreased cell death induced by ER stress. Immunodepletion of p23 or inhibition of p23 expression by siRNA resulted in enhancement of ER stress-induced cell death. While p23 co-immunoprecipitated with the BH3-only protein PUMA (p53-upregulated modulator of apoptosis) in untreated cells, prolonged ER stress disrupted this interaction. The results define a protective role for p23, and provide further support for a model in which ER stress is coupled to the mitochondrial intrinsic apoptotic pathway through the activities of BH3 family proteins.
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PMID:Coupling endoplasmic reticulum stress to the cell-death program: a novel HSP90-independent role for the small chaperone protein p23. 1619 41

In the present study, we have found evidence for ER stress occurring during development of the central nervous system in the mouse. Several ER-resident stress-regulated chaperones, such as calreticulin, glucose regulated protein 78, glucose regulated protein 94, ER protein 57 and protein disulfide isomerase, were expressed at higher levels in embryonic brain and retina, compared with adult tissues. In contrast, calnexin, a chaperone that is not regulated by stress was equally abundant in embryonic and adult tissues. We also detected unfolded protein response during embryonic development. Both eukaryotic translation initiation factor 2 alpha and its phosphorylated form were more abundant in embryonic brain and retina than in adult tissues. Spliced X-box binding protein-1 mRNA was detected in embryonic brain and retina, while it was absent in adult counterparts. Partially glycosylated form of activating transcription factor 6 alpha, another ER stress indicator, was detected predominantly in embryonic brain. Finally, apoptotic pathway components, caspase-7 and -12, were more abundant in embryonic brain than in adult. The pattern of expression of chaperones together with activation of the unfolded protein response factors suggests the presence of ER stress during development of brain and retina. Furthermore, our data suggest that ER stress-like mechanism may induce apoptosis via activation of the caspases during embryonic development of the central nervous system.
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PMID:Endoplasmic reticulum stress during the embryonic development of the central nervous system in the mouse. 1791 37

Glucose deprivation, a pathophysiological cell condition, causes up-regulation of GRP78 and induction of etoposide resistance in human cancer cells. The induction of drug resistance can be partly explained by the fact that GRP78 can block activation of caspase-7 induced by treatment with etoposide. Therefore, downregulating GRP78 expression may be a novel strategy anticancer drug development. Based on that premise, we established a screening program for anticancer agents that exhibit preferential cytotoxic activity for etoposide-resistant cancer cells under glucose-deprived conditions. We recently isolated an active compound, AR-054, from the culture broth of Streptomyces sp., which prevents stress-induced etoposide resistance in vitro. AR-054 was identified as piericidin A, a prototypical compound, by ESI-MS analysis and various NMR spectroscopic methods. Here, we showed that piericidin A suppressed the accumulation of GRP78 protein and was also highly toxic to etoposide-resistant HT-29 cells, with IC50 values for colony formation of 6.4 and 7.7 nM under 2-deoxyglucose supplemented and glucose-deprived conditions, respectively. Interestingly, piericidin A had no effect under normal growth conditions. Therefore, we suggest that piericidin A prevents up-regulation of GRP78, and exhibits cytotoxicity in glucose-deprived HT-29 cells that are resistant to etoposide.
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PMID:Etoposide-resistant HT-29 human colon carcinoma cells during glucose deprivation are sensitive to piericidin A, a GRP78 down-regulator. 1794 Oct 90

During recombinant Chinese hamster ovary (rCHO) cell culture, various events, such as feeding with concentrated nutrient solutions or the addition of base to maintain an optimal pH, increase the osmolality of the medium. To determine the effect of hyperosmotic stress on two types of programmed cell death (PCD), apoptosis and autophagy, of rCHO cells, two rCHO cell lines, producing antibody and erythropoietin, were subjected to hyperosmotic stress resulting from NaCl addition (310-610 mOsm/kg). For both rCHO cell lines, hyperosmolality up to 610 mOsm/kg increased cleaved forms of PARP, caspase-3, caspase-7, and fragmentation of chromosomal DNA, confirming the previous observation that apoptosis was induced by hyperosmotic stress. Concurrently, hyperosmolality increased the level of accumulation of LC3-II, a widely used autophagic marker, which was determined by Western blot analysis and confocal microscopy. When glucose and glutamine concentrations were measured during the cultures, glucose and glutamine concentrations in the culture medium at various osmolalities (310-610 mOsm/kg) showed no significant differences. This result suggests that induction of PCD by hyperosmotic stress occurred independently of nutrient depletion. Taken together, autophagy as well as apoptosis was observed in rCHO cells subjected to hyperosmolality.
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PMID:Hyperosmotic stress induces autophagy and apoptosis in recombinant Chinese hamster ovary cell culture. 2001 38

Upon nutrient depletion during recombinant Chinese hamster ovary (rCHO) cell batch culture, cells are subjected to apoptosis, type I programmed cell death (PCD), and autophagy which can be type II PCD or a cell survival mechanism. To investigate the effect of nutrient supplementation on the two PCDs and protein production in rCHO cells, an antibody-producing rCHO cell line was cultivated in batch and fed-batch modes. The feed medium containing glucose, amino acids, and vitamins was determined through flask culture tests and used in bioreactor cultures. In the bioreactor cultures, the nutrient feedings extended the culture longevity and enhanced antibody production. In addition, cells in the fed-batch culture showed delayed onset of both apoptosis and autophagy, compared with those in the batch culture. The inhibition of apoptosis was demonstrated by a decreased amount of cleaved caspase-7 protein and less fragmentation of chromosomal DNA. Concurrently, reduced LC3 conversion, from LC3-I to LC3-II, was observed in cells that received the feeds. Cultivation with pharmacological autophagy inducer (rapamycin) or inhibitor (bafilomycin A1) indicated that autophagy is necessary for the cells to survive under nutrient depletion. Taken together, the delayed and relieved cell death by nutrient supplementation could improve antibody production.
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PMID:Autophagy and apoptosis of recombinant Chinese hamster ovary cells during fed-batch culture: effect of nutrient supplementation. 2149 16


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