Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.62 (caspase-9)
 7,507 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidative stress and mitochondrial dysfunction are important aspects of pathogenesis, particularly in the brain, which is highly dependent on oxygen, and the protection of astrocytes is essential for neuroprotection. In this context, imidazoline drugs have been reported to be neuroprotective. Our recent study showed that imidazoline drugs, including guanabenz, inhibit the naphthazarin-induced oxidative cytotoxicity associated with lysosomal destabilization. We now report on a study into the protective effects of rilmenidine and AGN 192403, which have affinity for imidazoline-1 receptors, on the cytotoxicity induced by naphthazarin and inhibitors of mitochondrial respiration in astrocytes. Cytotoxicity was measured grossly by LDH release and by measuring changes in lysosomal membrane stability and features of mitochondrial membrane permeabilization. Naphthazarin-induced cytotoxicity was evidenced by the ordered development of lysosomal acridine orange relocation, decrease in mitochondrial potential, cytochrome c release, and caspase-9 activation, and was inhibited by guanabenz, rilmenidine, and AGN 192403. Antimycin A and rotenone induced mitochondrial dysfunction primarily, and their cytotoxicities were inhibited only by AGN 192403. Rilmenidine and guanabenz may have a lysosomal stabilizing effect, which underlies their protective effects. AGN 192403 might affect the mitochondrial cell death cascades, and had a novel protective effect on the cytotoxicity associated with mitochondrial dysfunction.
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PMID:Protective effects of rilmenidine and AGN 192403 on oxidative cytotoxicity and mitochondrial inhibitor-induced cytotoxicity in astrocytes. 1241 64

Beta-amyloid (Abeta) peptide has been suggested to play important roles in the pathogenesis of Alzheimer's disease (AD). Abeta peptide neurotoxicity was shown to induce disturbance of cellular calcium homeostasis. However, whether modulation of calcium release from the endoplasmic reticulum (ER) can protect neurons from Abeta toxicity is not clearly defined. In the present study, Abeta peptide-triggered ER calcium release in primary cortical neurons in culture is modulated by Xestospongin C, 2-aminoethoxydiphenyl borate or FK506. Our results showed that reduction of ER calcium release can partially attenuate Abeta peptide neurotoxicity evaluated by LDH release, caspase-3 activity and quantification of apoptotic cells. While stress signals associated with perturbations of ER functions such as up-regulation of GRP78 was significantly attenuated, other signaling machinery such as activation of caspase-7 transmitting death signals from ER to other organelles could not be altered. We further provide evidence that molecular signaling in mitochondria play also a significant role in determining neuronal apoptosis because Abeta peptide-triggered activation of caspase-9 was not significantly reduced by attenuating ER calcium release. Our results suggest that neuroprotective strategies aiming at reducing Abeta toxicity should include molecular targets linked to ER perturbations associated with ER calcium release as well as mitochondrial stress.
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PMID:Reduction of calcium release from the endoplasmic reticulum could only provide partial neuroprotection against beta-amyloid peptide toxicity. 1471 97

Two diterpenoids, oridonin (1) and ponicidin (2), were isolated from the 95% ethanol extract of Rabdosia rubescens and were evaluated for antiproliferative activity on cancer cells and human peripheral blood mononuclear cells (PBMC) in vitro. Oridonin has much more potent cytotoxic effects on four tumor cells (human melanoma A375-S2, human cervical cancer HeLa, human breast adenocarcinoma MCF-7, murine fibrosarcoma L929) than does ponicidin. The growth-inhibitory activity of oridonin for A375-S2 cells was more potent than that for the other cell lines, with an IC50 of 15.1 +/- 1.2 micromol L(-1). Treatment with oridonin (34.3 micromol L(-1)) for 12 h significantly inhibited A375-S2 cell growth, and showed weaker cytotoxicity against PBMC. By contrast, ponicidin markedly inhibited the growth of PBMC under the same conditions. When caspases-3 and -8 were activated at early stages after treatment of A375-S2 cells with oridonin (34.3 micromol L(-1)), apoptotic bodies were formed, nuclear damage was observed by Hoechst 33258 staining and DNA fragmentation was exhibited. In addition, oridonin increased the expression of the apoptosis inducer, Bax, promoted the release of cytochrome c without affecting Bcl-2 expression, and activated down-stream caspase-9 in the mitochondrial pathway. These observations indicated that an appropriate dose of oridonin gave an initial premitochondrial phase that involved the Bcl-2 family of the pro-apoptotic protein Bax that required the participation of caspase-9 and caspase-3. However, on treatment with oridonin (137.4 micromol L(-1)) for 12 h, the majority of A375-S2 cells underwent necrosis as measured by an LDH activity-based assay. Our results suggest that oridonin induces A375-S2 cell death on the balance of apoptosis and necrosis.
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PMID:Oridonin induced A375-S2 cell apoptosis via bax-regulated caspase pathway activation, dependent on the cytochrome c/caspase-9 apoptosome. 1500 59

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.
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PMID:Arsenic trioxide triggers a regulated form of caspase-independent necrotic cell death via the mitochondrial death pathway. 1567 46

Chronic alcohol consumption depletes hepatic vitamin A stores. However, vitamin A supplementation is hepatotoxic, which is further potentiated by concomitant alcohol consumption. It was suggested that polar retinol metabolites generated by alcohol-inducible cytochrome P4502E1 aggravate liver damage. However, experimental evidence supporting this hypothesis is lacking. To elucidate the effects of polar retinol metabolites on cultured HepG2 cells and primary rat hepatocytes, polar retinol metabolites were extracted from liver tissues of rats fed either an alcoholic or isocaloric control Lieber-DeCarli diet. Cell toxicity assays included morphology assessment, trypan blue exclusion test, and LDH/AST leakage. Staining for DAPI and acridine orange, FACS analysis, and Western blot for cleaved caspase-9 and -3 were used to detect apoptosis. Polar retinol metabolites caused marked cytotoxicity in a concentration- and time-dependent manner in both cell types reflected by morphological changes, a dramatic increase in trypan blue positive cells, and LDH/AST leakage. Toxicity was due to apoptosis, as demonstrated by a time-dependent increase of sub-G1 cellular events, a rapid loss of mitochondrial membrane potential, and a time-dependent activation of caspase-9 and -3. No toxicity was found with equivalent doses of the control extract from nonalcoholic rats. We demonstrate that polar retinol metabolites cause marked hepatocyte death through the induction of apoptosis.
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PMID:Hepatotoxicity of alcohol-induced polar retinol metabolites involves apoptosis via loss of mitochondrial membrane potential. 1573 Dec 94

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.
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PMID:Glycine- and proline-rich glycoprotein isolated from Solanum nigrum Linne activates caspase-3 through cytochrome c in HT-29 cells. 1607 93

This laboratory has shown that MT-3 expression determines the choice between apoptotic or necrotic cell death in Cd(+2)-exposed human proximal tubule cells. Human proximal tubule cells that express MT-3 undergo necrosis when exposed to Cd(+2), while cells that have no basal expression of MT-3 undergo apoptotic cell death. It was also shown that cells which express MT-3 were more sensitive to Cd(+2)-induced cell death than those having no basal expression. In the present study, site directed mutagenesis was used to determine if the unique N-terminal sequence of MT-3 was required for these activities regarding toxicity and cell death. The results demonstrated that HK-2 cells stably transfected with MT-3 that had been modified by converting the 2 prolines at amino acid positions 7 and 9 to threonines was no longer active in promoting necrotic cell death at lower levels of Cd(+2) exposure. This was shown in comparison to cells containing the wild type MT-3 sequence and blank vector controls as regards the % of DAPI-stained fragmented nuclei, DNA laddering, LDH release, caspase-9, and caspase-3 activation. This study demonstrates that the unique N-terminal sequence of MT-3 is required to elicit an effect on the mechanism of Cd(+2)-induced death of the proximal tubule cell. This is the identical sequence that has been shown to be responsible for the growth inhibitory activity of MT-3 in the neural system.
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PMID:The unique N-terminal sequence of metallothionein-3 is required to regulate the choice between apoptotic or necrotic cell death of human proximal tubule cells exposed to Cd+2. 1638 43

Nitric oxide (NO) is an unstable molecule with physiological and pathological properties. In brain, NO acts as a modulator of neurotransmission as well as a protector against neuronal death from several death stimuli. However, beside this protector effect, high NO concentrations produce neuronal death by a mechanism in which the caspase pathway is implicated. In this work, we demonstrate that in cortical neurons the NO toxicity is mediated by mitochondrial dysfunction. SNAP, an NO donor, induces apoptosis in these cells because it 1) increases the p53 and 2) induces cytochrome c release and activation of caspase-9 and caspase-3. SNAP also induces necrosis, through 1) breakdown of the mitochondrial membrane potential, 2) ATP decrease, 3) ROS formation, and 4) LDH and ATP release, indicative of oxidative stress and death by necrosis. To sum up, in cortical neurons, high NO concentrations produced cellular death by both an apoptotic and a necrotic mechanism in which the mitochondria are implicated.
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PMID:Mitochondrial involvement in nitric oxide-induced cellular death in cortical neurons in culture. 1639 99

Tetramethylpyrazine (TMP), a compound purified from Rhizoma Ligustici, is a widely used active ingredient in Chinese herbal medicine to treat cardiovascular diseases on account of its vasodilatory actions and antiplatelet activity. Studies have shown that TMP can remove oxygen free radicals and protect rat kidney from ischemia-reperfusion injury. In addition, adriamycin-induced nephrosis in rats is commonly used in pharmacological studies of human chronic renal diseases. Apoptosis of renal tubular cells has been reported in adriamycin-treated rats. To examine the therapeutic potential of TMP on chronic progressive renal diseases, adriamycin-induced injury in rat renal tubular cells NRK-52E has been used to monitor its protective effect. In TUNEL staining, TMP showed a dose-dependent protective effect against adriamycin-induced apoptosis in NRK-52E cells. Pretreatment of the cells with 10 or 100 microM of TMP effectively decreased the reactive oxygen species (ROS) formation induced by adriamycin, as measured in fluorescent assays. TMP was found to reduce the adriamycin-stimulated activities of caspase-3, caspase-8 and caspase-9, inhibit adriamycin-induced release of cytochrome C, and elevate the expression of Bcl-x (L). TMP was also able to inhibit the death receptor signaling pathway and suppress the activation of transcription factor NF-kappaB in adriamycin-treated NRK-52E cells. Based on the results of this study, we suggest that TMP can attenuate adriamycin-induced oxidative stress and apoptotic injury in NRK-52E cells, and that it may have therapeutic potential for patients with renal diseases. TMP: tetramethylpyrazine LDH: lactate dehydrogenase ROS: reactive oxygen species DCF: 2',7'-dichlorofluorescein TNF-alpha: tumor necrosis factor-alpha TUNEL: terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling.
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PMID:Tetramethylpyrazine attenuates adriamycin-induced apoptotic injury in rat renal tubular cells NRK-52E. 1690 63

The phototoxicity of low-energy ultraviolet radiation, such as UVA, can be enhanced by the presence of photosensitizing agents. Hence, co-exposure of cells to benzo[a]pyrene (BaP), a widespread environmental carcinogen and photosensitizing agent, and UVA may synergistically induce DNA damage. In this study, exposure of cells to various concentrations of BaP for 1h followed by UVA irradiation (2J/cm(2)) increased DNA damage and decreased cell viability. Expression of apoptosis-related proteins (caspase-9, caspase-3, PARP, and Bax) and hypodiploid DNA content (sub-G(1)) were not changed. LDH release into the culture medium increased in a dose-dependent manner with BaP under UVA irradiation, suggesting that cell death due to BaP/UVA co-treatment occurred via necrosis. Intracellular reactive oxygen species (ROS) levels were increased significantly in the co-exposed cells, and treatment with the polyphenol quercetin, but not with sodium azide or N-acetylcysteine, decreased ROS levels and increased cell viability in BaP/UVA-treated cells. In conclusion, UVA irradiation combined with BaP synergistically promoted necrosis of A549 cells by increasing intracellular ROS levels, and quercetin prevented BaP-enhanced phototoxicity due to UVA irradiation.
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PMID:Quercetin prevents necrotic cell death induced by co-exposure to benzo(a)pyrene and UVA radiation. 1894 85


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