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)

Cell death is generally believed to occur either by accidental, lytic necrosis or by programmed cell death, that is, apoptosis. The initiation and execution of cell death, however, is far more complex and includes pathways like caspase-independent apoptosis or actively triggered necrosis. In this study, we investigated the mechanisms of cell death induced by arsenic trioxide (arsenite, As2O3), a clinically efficient agent in anticancer therapy. As2O3-induced cell death coincides with cytochrome c release, facilitates mitochondrial permeability transition and is sensitive to inhibition by Bcl-x(L), indicating that cell demise is regulated through the mitochondrial apoptosis pathway. Nevertheless, only little caspase-3 activation was observed and As2O3-induced cell death was only weakly obstructed by the broad spectrum caspase inhibitor z-VAD-fmk. Moreover, disruption of caspase-9 or -2 failed to decrease the amount of As2O3-mediated cell death. Interestingly, As2O3-induced cell death had a predominantly necrosis-like phenotype as assessed by Annexin-V/propidium iodide staining and LDH release. Finally, blocking glutathione synthetase by buthionine sulfoximine enhanced the As2O3-mediated necrosis-like cell death without increasing caspase-3 cleavage. As2O3 does, however, not directly inhibit caspases, but appears to interfere with caspase activation. Altogether, our data clearly delineate a mode of As2O3-triggered cell death that differs considerably from that induced by conventional anticancer drugs. These findings may explain the capability of As2O3 to efficiently kill even chemoresistant tumor cells with disturbed apoptosis signaling and caspase activation, a frequent finding in malignancy.
 ...
PMID:Arsenic trioxide triggers a regulated form of caspase-independent necrotic cell death via the mitochondrial death pathway. 1567 46

The mechanism of ricin-induced apoptosis in human cervical cancer cell line HeLa was studied. The present study demonstrated that ricin induces apoptosis of human cervical cancer cells (HeLa) in a time dependent manner with an IC(50) for cell viability of 1 microg/ml. Ricin treatment resulted in a time dependent increase in LDH leakage, DNA fragmentation, percent apoptotic cells, generation of reactive oxygen species and depletion of intracellular glutathione levels. DNA agarose gel electrophoresis showed typical oligonucleosomal length DNA fragmentation. Additionally, DNA diffusion assay was performed to confirm DNA damage and apoptosis. Ricin activated caspase-3 as evidenced by both proteolytic cleavage of procaspase-3 into 20 and 18 kDa subunits, and increased protease activity. Caspase activity was maximum at 4h and led to the cleavage of 116 kDa poly(ADP-ribose) polymerase (PARP), resulting in the 85 kDa cleavage product. Ricin-induced caspase-3 activation also resulted in cleavage of DNA fragmentation factor-45 (DFF45/ICAD) and DFF40 or caspase-activated DNase in HeLa cells. Activation of caspase-3, cleavage of PARP and DNA fragmentation was blocked by pre-treatment with caspase-3 specific inhibitor Ac-DEVD-CHO (100 microM) and broad-spectrum caspase inhibitor Z-VAD-FMK (40 microM). Ricin-induced DNA fragmentation was inhibited by pre-treatment with PARP inhibitors 3-aminobenzamide (100 microM) and DPQ (10 microM). Our results indicate that ricin-induced cell death was mediated by generation of reactive oxygen species and subsequent activation of caspase-3 cascade followed by down stream events leading to apoptotic mode of cell death.
 ...
PMID:Mechanism of ricin-induced apoptosis in human cervical cancer cells. 1571 Mar 62

Enteric gram-negative bacilli, such as Escherichia coli are the most common cause of nosocomial pneumonia. In this study a wild-type extraintestinal pathogenic strain of E. coli (ExPEC)(CP9) and isogenic derivatives deficient in hemolysin (Hly) and cytotoxic necrotizing factor (CNF) were assessed in vitro and in a rat model of gram-negative pneumonia to test the hypothesis that these virulence factors induce neutrophil apoptosis and/or necrosis/lysis. As ascertained by in vitro caspase-3/7 and LDH activities and neutrophil morphology, Hly mediated neutrophil apoptosis at lower E. coli titers (1 x 10(5-6) cfu) and necrosis/lysis at higher titers (> or =1 x 10(7) cfu). Data suggest that CNF promotes apoptosis but not necrosis or lysis. We also demonstrate that annexin V/7-amino-actinomycin D staining was an unreliable assessment of apoptosis using live E. coli. The use of caspase-3/7 and LDH activities and neutrophil morphology supported the notion that necrosis, not apoptosis, was the primary mechanism by which neutrophils were affected in our in vivo gram-negative pneumonia model using live E. coli. In addition, in vivo studies demonstrated that Hly mediates lung injury. Neutrophil necrosis was not observed when animals were challenged with purified lipopolysaccharide, demonstrating the importance of using live bacteria. These findings establish that Hly contributes to ExPEC virulence by mediating neutrophil toxicity, with necrosis/lysis being the dominant effect of Hly on neutrophils in vivo and by lung injury. Whether Hly-mediated lung injury is due to neutrophil necrosis, a direct effect of Hly, or both is unclear.
 ...
PMID:E. coli virulence factor hemolysin induces neutrophil apoptosis and necrosis/lysis in vitro and necrosis/lysis and lung injury in a rat pneumonia model. 1580 36

Isolated hepatocytes in suspension express most of the functional activities of the intact liver and offer an easy-to-handle in vitro system for investigating both the biotransformation and damaging effects induced after a single exposure to xenobiotics upto 3-4h. There is, however, a general lack of consensus with respect to the choice of a suitable suspension medium. This motivated us to perform a comparative study of the effects of five frequently used bicarbonate-based media (Ca(2+)-containing Krebs-Henseleit buffer (KHB) with or without 25mM HEPES, 10mM glucose and 2% (g/v) BSA supplements, and Williams' E culture medium) on the viability (LDH leakage, caspase-3 processing and activity, Bid/Bax expression) and functionality (energy status, glutathione content, phases I and II biotransformation) of freshly isolated rat hepatocytes in suspension upto 3h. Also included was the bicarbonate-free HEPES buffer that does not require carbogen gassing, and is therefore handled more easily. The results clearly demonstrated that the type of incubation medium profoundly affected the functionality of the suspended hepatocytes, changing their sensitivity and response to exogenous damaging effects. While HEPES buffer and Williams' E medium offered the lowest background of spontaneous cell death, bicarbonate-based buffers and media seemed more suitable for obtaining both phases I and II biotransformation. Williams' E medium ensured a constant glutathione content of the cells and a lower level of oxidative stress.
 ...
PMID:Spontaneous apoptosis, necrosis, energy status, glutathione levels and biotransformation capacities of isolated rat hepatocytes in suspension: effect of the incubation medium. 1593 51

Reversible protein phosphorylation regulates the biological activities of many human proteins involved in crucial cellular processes, e.g., protein-protein interactions, cell signaling, gene transcription, cell growth, and death. A malfunction of cellular homeostasis in retinal pigment epithelial (RPE) cells is involved in the age-related retinal degeneration. In this study, we examined cytotoxicity in human RPE cells subjected to the protein phosphatase inhibitor, okadaic acid (OA). Moreover, the influence of Hsp90 inhibitor geldanamycin (GA), a benzoquinone ansamycin, in cytoprotection was assessed. Hsp70 protein levels were analyzed by Western blot. Cellular viability was determined by LDH and MTT assays. To study apoptotic cell death, caspase-3 enzyme activity was measured by assaying the cleavage of a fluorescent peptide substrate and Hoechst dye was used to visualize nuclear morphology. OA treatment caused morphological changes and induced cytotoxicity by caspase-3-independent manner in the RPE cells. No evidence of nuclear fragmentation was observed in response to OA. Interestingly, GA treatment accumulated Hsp70 protein and attenuated OA-induced cytotoxicity. This study suggests that Hsp70 and Hsp90 are closely related to cytoprotection of RPE cells in response to protein phosphatase inhibition.
 ...
PMID:Geldanamycin activates Hsp70 response and attenuates okadaic acid-induced cytotoxicity in human retinal pigment epithelial cells. 1595 Jul 70

The alpha-ketoglutarate dehydrogenase complex (KGDHC) is a mitochondrial enzyme in the TCA cycle. Inhibition of KGDHC activity by alpha-keto-beta-methyl-n-valeric acid (KMV) is associated with neuron death. However, the effect of KMV in microglia is unclear. Therefore, we investigated the effect of KMV on BV-2 microglial cells exposed to hypoxia or oxidative stress. The results showed that KMV (1-20 mM) enhanced the cell viability under hypoxia. KMV dose-dependently reduced ROS and LDH releases from hypoxic BV-2 cells. KMV also reduced ROS production and enhanced the cell viability under H2O2 but failed to reduce the SIN-1 and sodium nitroprusside (SNP) toxicity. KMV also reduced caspase-3 and -9 activation under stress. These results suggest that KMV protects BV-2 cells from stress and acts by reducing ROS production through inhibition of KDGHC.
 ...
PMID:Protective effect of alpha-keto-beta-methyl-n-valeric acid on BV-2 microglia under hypoxia or oxidative stress. 1596 72

Icariin is a flavonoid isolated from Epimedium and is considered to be the major pharmacological active component of Epimedii Herba. In the present investigation, we studied and confirmed the protective activity of icariin on H2O2-induced injury in human umbilical vein endothelial cell line: ECV-304. Eighteen-hour treatment with 750 micromol l(-1) H2O2 significantly decreased the viability of ECV-304 cells, which was accompanied with apparent apoptotic features, including distinct cell morphological alteration and the increase of caspase-3 expression. In addition, it is observed that H2O2 increased the amounts of malondialdenhyde (MDA) and the dehydrogenase (LDH), and decreased the content of nitric oxide (NO) in ECV-304 cells. However, pretreatment with 0.1-50 micromol l(-1) icariin resulted in a significant recovery from H2O2-induced cell apoptosis. Also, it decreased other H2O2-induced damage in a concentration-dependent manner. Furthermore, pretreatment with icariin decreased the expression of caspase-3, which was known to be involved as a key role executor in H2O2-induced cell apoptosis. The endothelial cells apoptosis were detected by acridine orange/ethidium bromide (AO/EB) dual staining as well as flow cytometry, and the expression of pro-apoptotic factor caspase-3 were detected by immunocytochemical method. Taken together, these data suggest that protective effects of icariin against oxidative injuries of ECV-304 cells may be achieved via decreasing of caspase expression.
 ...
PMID:Protective effects of icariin on human umbilical vein endothelial cell injury induced by H2O2 in vitro. 1596 84

In the present study the role of endothelin (ET) and its receptors (ETA-R and ETB-R) in cellular mechanisms underlying the resistance of astroglial cells to low oxygen level and development of hypoxia has been investigated. To define the influences of ET and its receptors on survival and on antigenic as well as morphologic differentiation of rat astroglial cells in normoxic (NC) and hypoxic culture (HC) the selective antagonists of ETA-R (BQ-123) and ETB-R (BQ-788) were used. Treatment of HC with BQ-123 caused an increase in cell number and inhibited the hypoxia-induced apoptosis by 37%. BQ-123 decreased the hypoxia-induced cytotoxicity in HC. These effects of BQ-123 were abolished in cultures simultaneously treated with BQ-123 and BQ-788. Administration of BQ-788 alone decreased the number of living cells in NC, but not in HC. The activity of caspase-3/-7 was not changed by exposure of NC and HC to BQ-788. The protection provided by BQ-123 to astroglial cells against cytotoxicity in NC and HC was similar to that of erythropoietin (EPO), a cytokine with established neuroprotective effects. The functional improvement of astroglial cells and slowing down of their differentiation under exposure to BQ-123, or EPO, or BQ-123 + EPO has been evidenced by an increased number of nestin+/glial fibrillary acidic protein-positive (GFAP+) astrocytes accompanied by decrease of nestin-/GFAP+ cells. The simultaneous treatment with BQ-123 and EPO additionally decreased the activities of caspase-3/-7 (64%) and release of LDH into the medium (94%). The benefits in the functional states of astrocytes obtained by combined treatment of HC with BQ-123 and EPO suggest a new therapeutic strategy in treatment of hypoxic brain injury.
 ...
PMID:The blockade of endothelin A receptor protects astrocytes against hypoxic injury: common effects of BQ-123 anderythropoietin on the rejuvenation of the astrocyte population. 1600 10

This study was carried out to investigate apoptotic effects of the glycoprotein (SNL glycoprotein, 150 kDa) isolated from Solanum nigrum Linne, which has been used as an anti-pyretic and anti-cancer agent in folk medicine. We found that the SNL glycoprotein consists of carbohydrate (69.74%) and protein content (30.26%), which has >50% hydrophobic amino acids containing glycine and proline. LDH assay indicated that the SNL glycoprotein has obvious cytotoxic and apoptotic effects (>50% cell death) at 40 microg/ml SNL glycoprotein for 2 h in HT-29 cells. The results showed that the SNL glycoprotein has a stimulatory effect on the release of mitochondrial cytochrome c, cleavages of pro-caspase-9, pro-caspase-3, and poly(ADP-ribose) polymerase (PARP) proteins in HT-29 cells. However, the SNL glycoprotein did not significantly stimulate or change the levels of intracellular reactive oxygen species (ROS). The results of this experiment suggest that the SNL glycoprotein activates caspase-3 in HT-29 cells, independent of ROS.
 ...
PMID:Glycine- and proline-rich glycoprotein isolated from Solanum nigrum Linne activates caspase-3 through cytochrome c in HT-29 cells. 1607 93

Oxidative injury induces cellular and nuclear damages that lead to cell injury. Agents or antioxidants that can inhibit production of reactive oxygen species can prevent injury. We tested the hypothesis that silybin can inhibit H2O2-induced injury in human umbilical vein endothelial cells. Eighteen hours of treatment with 750 micromol l(-1) H2O2 significantly stimulated expression of caspase-3 and cell apoptosis. In addition, it is observed that H2O2 increased the amounts of malondialdenhyde (MDA), the dehydrogenase (LDH) leakage, and decreased the activity of GSH-Px and NO contents in ECV-304 cells. In the H2O2 apoptosis model, the addition of 6.25-25 mg/L of silybin, which has in vitro radical scavenging activity, partially restored cell viability with a reduction in H2O2-induced apoptotic DNA damage, and decreased the expression of caspase-3. Moreover, it decreased other H2O2-induced damage in a concentration-dependent manner. The endothelial cell apoptosis was detected by AO/EB dual staining as well as flow cytometry, and the activity of pro-apoptotic factor caspase-3 was detected by immunocytochemical method. Our results suggest that the antioxidant, silybin, protects ECV-304 cells against H2O2-induced injury probably through its antioxidant activity, increasing the NO content, the activity GSH-Px and inhibiting signaling pathways mediated by caspase-3.
 ...
PMID:Protective effects of silybin on human umbilical vein endothelial cell injury induced by H2O2 in vitro. 1611 23


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>