Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have attempted to elucidate the precise mechanism of nitric oxide (NO)-induced apoptotic neuronal cell death. Enzymatic cleavages of DEVD-AFC, VDVAD-AFC, and LEHD-AFC (specific substrates for caspase-3-like protease (caspase-3 and -7), caspase-2, and caspase-9, respectively) were observed by treatment with NO. Western blot analysis showed that pro-forms of caspase-2, -3, -6, and -7 are decreased during apoptosis. Interestingly, Ac-DEVD-CHO, a caspase-3-like protease inhibitor, blocked not only the decreases in caspase-2 and -7, but also the formation of p17 from p20 in caspase-3 induced by NO, suggesting that caspase-3 exists upstream of caspase-2 and -7. Bongkrekic acid, a potent inhibitor of mitochondrial permeability transition, specifically blocked both the loss of mitochondrial membrane potential and subsequent DNA fragmentation in response to NO. Thus, NO results in neuronal apoptosis through the sequential loss of mitochondrial membrane potential, caspase activation, and degradation of inhibitor of caspase-activated DNase (CAD) (CAD activation).
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PMID:Mechanism of nitric oxide-induced apoptosis in human neuroblastoma SH-SY5Y cells. 1107 88

Apoptosis is an important process in normal animal development as well as in diseases, and inhibitor of apoptosis protein (IAP) is one of the important factors that regulate apoptotic cell death. We found that lipopolysaccharide (LPS) enhances the expression of mRNA and protein of cellular IAP-2 (cIAP2) in human monoblastic U937 cells differentiated by phorbol ester pretreatment. cIAP2 mRNA was not detected in undifferentiated U937 cells. mRNAs of cIAP1 and X-chromosome-linked IAP (XIAP) were expressed constitutively and not affected by LPS in both undifferentiated and differentiated cells. LPS stimulated the expression of cIAP2 mRNA and protein in time- and concentration-dependent manners. LPS enhanced the expression of cIAP2 mRNA and protein in human monocyte-derived macrophages, which was associated with the inhibition of the caspase-3 activation, i.e., decrease in active p17 fragment of caspase-3 with simultaneous accumulation of precursor p20 fragment. We conclude that LPS may inhibit apoptosis of macrophages, at least in part, through the induction of cIAP2.
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PMID:Lipopolysaccharide induces the expression of cellular inhibitor of apoptosis protein-2 in human macrophages. 1111 65

Myelodysplastic syndromes (MDS) are characterized by abnormal growth of committed progenitors in clonogenic assay, with reduced number of colonies and decreased colony/cluster ratio. It has been suggested that excessive apoptosis is the cause of marrow failure in MDS. We studied the expression of caspase-1 (interleukin-1beta-converting enzyme, ICE) and caspase-3 (CPP32/apopain) in marrow mononuclear cells, and the growth pattern of committed progenitors in a series of 83 MDS cases. The percentage of apoptotic cells as detected by TUNEL technique, and the percentage of caspase-3-positive cells were significantly higher in refractory anemia (RA) and RA with ringed sideroblasts (RAS) than in chronic myelomonocytic leukemia (CMML), refractory anemia with excess of blasts (RAEB) and RAEB in transformation (RAEB-T). Spontaneous growth of CFU-GM was associated with a higher percentage of blasts, and with a lower expression of caspase-3 and caspase-1. The yield of CFU-E, BFU-E, and CFU-GM (in the presence of growth factors) was decreased by comparison to normal marrow, but large individual differences were observed in all cytological categories. Inhibition of caspase-1 and caspase-3 activities by specific inhibitors resulted in a significant increase of the production of all types of colonies (up to 50-fold of control). In the presence of caspase-3 inhibitor, the number of BFU-E and CFU-E was in the range of normal values in most cases of RA and RAS. In addition, caspase-1 and -3 protease activities were detectable by fluorogenic assay in all cases studied. Western blot analysis confirmed the expression of caspase-3, including the cleaved (activated)-p17 form in most cases of RA/RAS analyzed. It is concluded that caspase-3 is implicated in the increased apoptosis observed in MDS and that inhibition of its activity can restore at least partially the growth of committed progenitors.
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PMID:Expression and activity of caspases 1 and 3 in myelodysplastic syndromes. 1118 88

Divalent cations, including Zinc and Manganese ions, are important modulators of cell activation. We investigated the ability of these two divalent cations to modulate apoptosis in human Burkitt lymphoma B cells line (Ramos). We found that Zinc (from 10 to 50 microM) inhibited Manganese-induced caspase-3 activation and apoptosis of Ramos cells. Higher concentration of Zinc (50 to 100 microM) did not prevent Manganese-mediated apoptosis but rather increased cell death among Ramos cells. This Zinc-mediated cell death was associated with apoptotic features such as cell shrinkage, the presence of phosphatidylserine residues on the outer leaflet of the cells, chromatin condensation, DNA fragmentation and decrease of mitochondrial transmembrane potential. Zinc-mediated apoptosis was associated with caspase-9 and caspase-3 activation as revealed by the appearance of active p35 fragment of caspase-9 and p19 and p17 of caspase-3 as well as in vivo cleavage of PARP and of a cell-permeable fluorogenic caspase-3 substrate (Phiphilux-G(1)D(2)). Both Zinc-mediated apoptosis and caspase-3 activation were prevented by the cell-permeable, broad-spectrum inhibitor of caspases (zVAD-fmk) or overexpression of bcl-2. In addition, we show that Zinc-induced loss of transmembrane mitochondrial potential is a caspase-independent event, since it is not modified by the presence of zVAD-fmk, which is inhibited by overexpression of bcl-2. These results indicate that depending on its concentration, Zinc can exert opposite effects on caspase-3 activation and apoptosis in human B lymphoma cells: concentrations below 50 microM inhibit caspase-3 activation and apoptosis whereas higher concentrations of Zinc activate a death pathway associated with apoptotic-like features and caspase-3 activation.
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PMID:Zinc-mediated regulation of caspases activity: dose-dependent inhibition or activation of caspase-3 in the human Burkitt lymphoma B cells (Ramos). 1131 17

Bisphosphonates inhibit osteoclast-mediated bone resorption by mechanisms that have only recently become clear. Whereas nitrogen-containing bisphosphonates affect osteoclast function by preventing protein prenylation (especially geranylgeranylation), non-nitrogen-containing bisphosphonates have a different molecular mechanism of action. In this study, we demonstrate that nitrogen-containing bisphosphonates (risedronate, alendronate, pamidronate, and zoledronic acid) and non-nitrogen-containing bisphosphonates (clodronate and etidronate) cause apoptosis of rabbit osteoclasts, human osteoclastoma-derived osteoclasts, and human osteoclast-like cells generated in cultures of bone marrow in vitro. Osteoclast apoptosis was shown to involve characteristic morphological changes, loss of mitochondrial membrane potential, and the activation of caspase-3-like proteases capable of cleaving peptide substrates with the sequence DEVD. Caspase-3-like activity could be visualized in unfixed, dying osteoclasts and osteoclast-like cells using a cell-permeable, fluorogenic substrate. Bisphosphonate-induced osteoclast apoptosis was dependent on caspase activation, because apoptosis resulting from alendronate, clodronate, or zoledronic acid treatment was suppressed by zVAD-fmk, a broad-range caspase inhibitor, or by SB-281277, a specific isatin sulfonamide inhibitor of caspase-3/-7. Furthermore, caspase-3 (but not caspase-6 or caspase-7) activity could be detected and quantitated in lysates from purified rabbit osteoclasts, whereas the p17 fragment of active caspase-3 could be detected in human osteoclast-like cells by immunofluorescence staining. Caspase-3, therefore, appears to be the major effector caspase activated in osteoclasts by bisphosphonate treatment. Caspase activation and apoptosis induced by nitrogen-containing bisphosphonates are likely to be the consequence of the loss of geranylgeranylated rather than farnesylated proteins, because the ability to cause apoptosis and caspase activation was mimicked by GGTI-298, a specific inhibitor of protein geranylgeranylation, whereas FTI-277, a specific inhibitor of protein farnesylation, had no effect on apoptosis or caspase activity.
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PMID:Visualization of bisphosphonate-induced caspase-3 activity in apoptotic osteoclasts in vitro. 1134 45

Nitric oxide (NO) plays an important role in the regulation of the functional integrity of the endothelium. The intracellular reaction of NO with reactive cysteine groups leads to the formation of S-nitrosothiols. To investigate the regulation of S-nitrosothiols in endothelial cells, we first analyzed the composition of the S-nitrosylated molecules in endothelial cells. Gel filtration revealed that more than 95% of the detected S-nitrosothiols had a molecular mass of more than 5000 Da. Moreover, inhibition of de novo synthesis of glutathione using N-butyl-sulfoximine did not diminish the overall cellular S-NO content suggesting that S-nitrosylated glutathione quantitatively plays only a minor role in endothelial cells. Having demonstrated that most of the S-nitrosothiols are proteins, we determined the regulation of the S-nitrosylation by pro-inflammatory and pro-atherogenic factors, such as TNFalpha and mildly oxidized low density lipoprotein (oxLDL). TNFalpha and oxLDL induced denitrosylation of various proteins as assessed by Saville-Griess assay, by immunostaining with an anti-S-nitrosocysteine antibody, and by a Western blot approach. Furthermore, the caspase-3 p17 subunit, which has previously been shown to be S-nitrosylated and thereby inhibited, was denitrosylated by TNFalpha treatment suggesting that S-nitrosylation and denitrosylation are important regulatory mechanisms in endothelial cells contributing to the integrity of the endothelial cell monolayer.
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PMID:TNFalpha and oxLDL reduce protein S-nitrosylation in endothelial cells. 1152 31

Bcl-2 and Bcl-x(L) are reported to inhibit CD95-mediated apoptosis in "type II" but not in "type I" cells. In the present studies, we found that stimulation of CD95 receptors, with either agonistic antibody or CD95 ligand, resulted in the activation of caspase-8, which in turn processed caspase-3 between its large and small subunits. However, in contrast to control cells, those overexpressing either Bcl-2 or Bcl-x(L) displayed a distinctive pattern of caspase-3 processing. Indeed, the resulting p20/p12 caspase-3 was not active and did not undergo normal autocatalytic processing to form p17/p12 caspase-3, because it was bound to and inhibited by endogenous X-linked inhibitor-of-apoptosis protein (XIAP). Importantly, Bcl-2 and Bcl-x(L) inhibited the release of both cytochrome c and Smac from mitochondria. However, since Smac alone was sufficient to promote caspase-3 activity in vitro by inactivating XIAP, we proposed the existence of a death receptor-induced, Smac-dependent and apoptosome-independent pathway. This type II pathway was subsequently reconstituted in vitro using purified recombinant proteins at endogenous concentrations. Thus, mitochondria and associated Bcl-2 and Bcl-x(L) proteins may play a functional role in death receptor-induced apoptosis by modulating the release of Smac. Our data strongly suggest that the relative ratios of XIAP (and other inhibitor-of-apoptosis proteins) to active caspase-3 and Smac may dictate, in part, whether a cell exhibits a type I or type II phenotype.
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PMID:Bcl-2 and Bcl-xL inhibit CD95-mediated apoptosis by preventing mitochondrial release of Smac/DIABLO and subsequent inactivation of X-linked inhibitor-of-apoptosis protein. 1180 95

We have assessed the distribution of caspase-3 in subcellular fractions from rabbit brain hippocampus and find that in controls the pro-caspase-3 form is distributed mainly in the cytoplasm. In animals treated intracisternally with the neurotoxin aluminum-maltolate, although pro-caspase-3 levels are higher in the cytosolic fractions, p17, the active caspase-3, is localized mainly in the endoplasmic reticulum. This distribution is confirmed by immunohistochemistry which demonstrates the co-localization of p17 with calnexin, a specific marker of the endoplasmic reticulum. Based on the apparent translocation into the endoplasmic reticulum of active caspase-3, an executioner of cell death, the results suggest that this organelle is an important site in the caspase-3 mediated apoptosis cascade. Inhibition of the latter enzyme by directly targeting its main site of activation could represent a strategy to prevent this adverse event.
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PMID:The endoplasmic reticulum is the main site for caspase-3 activation following aluminum-induced neurotoxicity in rabbit hippocampus. 1200 27

Previous experiments indicated that caspase-3 was a mediator of ionizing radiation(IR)-induced apoptosis in U937 cells. In present study the caspase-3 activity in IR-induced apoptosis was further measured by analyzing the Ac-DEVD-p-nitroanilide cleaving activity and results showed that caspase-3 activity increased in accordance to the development of apoptosis and reached peak at 6 h post-irradiation. However northern blot analysis showed that the expression of caspase-3 was not changed while Western blot found that the active P20 subunit concentration increased and from 3 h post-irradiation active P17 subunit also increased. These findings demonstrate that the increase of caspase-3 activity observed during IR-induced apoptosis depends on the activation of inactive pre-caspase rather than the change in gene expression.
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PMID:Caspase-3 Gene Activity in Radiation-induced Apoptosis. 1213 1

A caspase-3-activated DNase produces internucleosomal DNA cleavage (DNA laddering). We determined whether caspase-3 is activated by lithium-pilocarpine-induced status epilepticus in six brain regions with necrosis-induced DNA laddering. The thymuses of adult rats given methamphetamine or normal saline were used as controls for apoptosis. Some 6-8 h after methamphetamine treatment, thymocytes showed apoptosis by electron-microscopic examination, positive terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), DNA laddering, cleavage of caspase-3 into its active p17 subunit, active caspase-3 immunoreactivity, and a 25-fold increase in caspase-3-like activity. Six hours after SE, necrotic neurons by electron-microscopic examination in hippocampus, amygdala and piriform, entorhinal and frontal cortices showed no TUNEL and no DNA laddering. Twenty-four hours after seizures, most necrotic neurons were negative for TUNEL, some were positive, but all regions showed DNA laddering. However, 6 and 24 h after seizures, active caspase-3 immunoreactivity was negative, caspase-3-like activity did not increase, and western blot analysis failed to show the p17 subunit. In addition, 24 h after seizures,microdialytic perfusion of carbobenzoxy-valyl-alanyl-aspartyl (O-methylester) fluoromethylketone was not neuroprotective. Thus, caspase-3 is not activated in brain regions with seizure-induced neuronal necrosis with DNA laddering. Either caspase-activated DNase is activated by another enzyme, or a caspase-independent DNase is responsible for the DNA cleavage.
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PMID:Caspase-3 is not activated in seizure-induced neuronal necrosis with internucleosomal DNA cleavage. 1235 47


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