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:3.4.22.56 (caspase-3)
35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Persistent activation of the immune system is one of the hallmarks of HIV-1 infection. In this study we analysed the induction of factors involved in cytokine signal transduction, such as STAT 1 proteins and IRF-1 mRNA, in normal peripheral blood mononuclear cells (PBMC) exposed to HIV-infected cells, and the induction of apoptosis. Western blot analyses and reverse transcriptase-polymerase chain reaction results indicate that both cells infected with a X4 strain and cells infected with a R5 strain are able to increase intracellular levels of STAT 1alpha and beta proteins as well as IRF-1 mRNA. This effect was prevented by neutralizing antibodies against interferon-alpha (IFN-alpha). HIV-1-infected cells dose-dependently induced apoptotic commitment in normal PBMC, as revealed by DNA fragmentation analysis, but this was not accompanied by an increase of caspase-3 activity, even if a slight up-regulation of IL-1beta-converting enzyme mRNA was detected. Apoptosis induction could be abrogated mainly by antibodies against tumour necrosis factor-alpha (TNF-alpha) and, to a lesser extent, by antibodies against IFN-gamma. All these findings suggest that uninfected PBMC can undergo activation of signal transduction and apoptosis after exposure to bystander HIV-infected cells, subsequent to the induction of cytokines such as IFNs and TNF-alpha.
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PMID:Activation of signal transduction and apoptosis in healthy lymphomonocytes exposed to bystander HIV-1-infected cells. 1112 43

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by localized areas of demyelination. The mechanisms underlying oligodendrocyte (OLG) injury in MS and EAE remain unknown. Here we show that caspase-11 plays crucial roles in OLG death and pathogenesis in EAE. Caspase-11 and activated caspase-3 were both expressed in OLGs in spinal cord EAE lesions. OLGs from caspase-11-deficient mice were highly resistant to the cell death induced by cytotoxic cytokines. EAE susceptibility and cytokine concentrations in the CNS were significantly reduced in caspase-11-deficient mice. Our findings suggest that OLG death is mediated by a pathway that involves caspases-11 and -3 and leads to the demyelination observed in EAE.
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PMID:Caspase-11 mediates oligodendrocyte cell death and pathogenesis of autoimmune-mediated demyelination. 1113 25

Photodynamic therapy (PDT) is a novel cancer treatment utilizing a photosensitizer, visible light and oxygen. PDT with the silicon phthalocyanine Pc 4, a new photosensitizer, is highly effective in cancer cell destruction and tumor ablation. The mechanisms underlying cancer cell killing by PDT are not fully understood. Tumor necrosis factor alpha (TNF) is a multifunctional cytokine that has been implicated in photocytotoxicity. We asked whether recombinant human TNF (rhTNF) affects Pc 4-PDT cytotoxicity in A431 human epidermoid carcinoma cells. Co-treatment of A431 cells with various doses of Pc 4-PDT and a sub-lethal rhTNF dose led to a sub-additive reduction in cell survival. In addition, in the presence of Pc 4-PDT or rhTNF, caspase-3 activity and apoptosis were induced. The combined treatment, however, did not potentiate either caspase-3 activity or apoptosis. Similar to previous findings we observed that Pc 4-PDT initiated a time-dependent extracellular TNF accumulation. The data suggest that: a) PDT and rhTNF induce cancer cell killing through different mechanisms; and b) Pc 4-PDT-induced TNF production is a stress response that may not directly affect photocytotoxicity.
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PMID:Recombinant human tumor necrosis factor alpha does not potentiate cell killing after photodynamic therapy with a silicon phthalocyanine in A431 human epidermoid carcinoma cells. 1117 11

Degeneration of the dopamine (DA) neurons of the substantia nigra pars compacta and the resulting loss of nerve terminals accompanied by DA deficiency in the striatum are responsible for most of the movement disturbances called parkinsonism, observed in Parkinson's disease (PD). One hypothesis of the cause of degeneration of the nigrostriatal DA neurons is that PD is caused by programmed cell death (apoptosis) due to increased levels of cytokines and/or decreased ones of neurotrophins. We and other workers found markedly increased levels of cytokines, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-2, IL-4, IL-6, transforming growth factor (TFG)-alpha, TGF-beta1, and TGF-beta2, and decreased ones of neurotrophins, such as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), in the nigrostriatal DA regions and ventricular and lumbar cerebrospinal fluid of PD patients. Furthermore, the levels of TNF-alpha receptor R1 (TNF-R1, p55), bcl-2, soluble Fas (sFas), and the activities of caspase-1 and caspase-3 were also elevated in the nigrostriatal DA regions in PD. In experimental animal models of PD, IL-1beta level was increased and NGF one decreased in the striatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonian mice, and TNF-alpha level was increased in the substantia nigra and striatum of the 6-hydroxydopamine (6OHDA)-injected side of hemiparkinsonian rats. L-DOPA alone or together with 6OHDA does not increase the level of TNF-alpha in the brain in vivo. Increased levels of proinflammatory cytokines, cytokine receptors and caspase activities, and reduced levels of neurotrophins in the nigrostriatal region in PD patients, and in MPTP- and 6OHDA-produced parkinsonian animals suggest increased immune reactivity and programmed cell death (apoptosis) of neuronal and/or glial cells. These data indicate the presence of such proapoptotic environment in the substantia nigra in PD that may induce increased vulnerability of neuronal or glial cells towards a variety of neurotoxic factors. The probable causative linkage among the increased levels of proinflammatory cytokines and the decreased levels of neurotrophins, candidate parkinsonism-producing neurotoxins such as isoquinoline neurotoxins (Review; Nagatsu, 1997), and the genetic susceptibility to toxic factors, remains for further investigation in the molecular mechanism of PD. The increased cytokine levels, decreased neurotrophin ones, and the possible immune response in the nigrostriatal region in PD indicate new neuroprotective therapy including nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, immunosuppressive or immunophilin-binding drugs such as FK-506, and drugs increasing neurotrophins.
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PMID:Changes in cytokines and neurotrophins in Parkinson's disease. 1120 47

To evaluate the mechanisms of T-cell dysfunction in patients with gastric cancer, we investigated the caspase activity of T cells, the induction of spontaneous T-cell apoptosis, the expression of T-cell receptor (TCR) zeta molecules, and the ability of T cells to produce cytokines in peripheral blood lymphocytes from patients (n = 22) and healthy controls (n = 14). The caspase-3 activity of T cells was studied as the protease activity of caspase-3 using the cell-permeable substrate of PhiPhiLux G1D2. Flow cytometric analysis was performed with triple staining by annexin V-FITC, propidium iodide, and CD3-R-phycoerythrin-Cy5 for the detection of T-cell apoptosis and with intracellular staining using permeabilized cells for the expression of TCR-zeta molecules. IFN-gamma and tumor necrosis factor alpha production from T cells was evaluated in response to anti-CD3 stimulation. Caspase-3 activity of peripheral blood T cells from patients with advanced disease was significantly increased compared with that from controls [15.5 +/- 3.6 mean fluorescence intensity (MFI) versus 11.5 +/- 3.3 MFI; P = 0.0068]. Parallel to this, the apoptosis of peripheral blood T cells from patients with advanced disease was significantly higher than for those from controls (16.5 +/- 15.5% versus 4.8 +/- 2.7%; P = 0.010). Furthermore, the expression of TCR-zeta molecules in patients with advanced disease was significantly decreased in comparison with that of the controls (41.0 +/- 13.9 MFI versus 56.7 +/- 16.3 MFI; P = 0.014), and this decreased expression coexisted with impaired IFN-gamma (42.4 +/- 43.2 pg/ml versus 1,757.4 +/- 2449.0 pg/ml; P = 0.031) and tumor necrosis factor alpha (682.6 +/- 519.3 pg/ml versus 1,686.0 +/- 1,533.7 pg/ml; P = 0.041) production of T cells. Thus, peripheral blood T cells from gastric cancer patients simultaneously exhibit an elevated caspase-3 activity, an increased degree of T-cell apoptosis, a down-regulation of TCR-zeta molecules, and impaired cytokine production. These observations suggest that induction of T-cell apoptosis coexisting with a down-regulation of TCR-zeta molecules may be responsible for T-cell dysfunction in patients with gastric cancer.
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PMID:Elevated caspase-3 activity in peripheral blood T cells coexists with increased degree of T-cell apoptosis and down-regulation of TCR zeta molecules in patients with gastric cancer. 1120 21

There is increasing evidence that IL-18 is a key pro-inflammatory cytokine and an important mediator of Th1 immune response. The main source of IL-18 is macrophage-like cells. In the present study we have investigated IL-18 protein expression in primary human macrophages in response to influenza A and Sendai virus infections. Macrophages constitutively expressed proIL-18 but produced biologically active IL-18 only after virus infection. The IL-18 release was due to virus infection-induced proteolytic processing of 24-kDa proIL-18 into its mature 18-kDa form. ProIL-18 processing required active caspase-1 enzyme and the release of mature IL-18 was blocked with a caspase-1-specific inhibitor. Caspase-3 inhibitor also reduced IL-18 production in response to virus infection. Inactive proforms of caspase-1 and caspase-3 were basally expressed in macrophages, and virus infection induced the cleavage of procaspases into their mature forms. Besides increasing the expression of caspase proteins, virus infection enhanced caspase mRNA expression in macrophages. The enhancement of caspase gene expression was abrogated by anti-IFN-alpha antibody. Furthermore, IFN-alpha and IFN-gamma could induce caspase gene expression. These results imply that interferons are involved in virus-induced caspase activation that leads to proIL-18 processing and subsequent release of mature IL-18.
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PMID:Virus infection induces proteolytic processing of IL-18 in human macrophages via caspase-1 and caspase-3 activation. 1124 Dec 76

Proteins of the caspase family are involved in the signalling pathway that ultimately leads to programmed cell death (apoptosis), which has been reported to occur in some experimental models of stroke. In a previous paper we used quantitative reverse transcription and polymerase chain reaction (RT-PCR) to characterise changes in the mRNA expression of one member of this family, caspase-3, in a rat model of permanent focal ischemia. Here we have used this technique to study the expression of a further three caspases which are involved in different aspects of caspase signalling. Caspase-8, involved in Fas-mediated apoptosis, was upregulated in the cortex of ischemic rats. Caspase-11, which leads to the synthesis of the functional form of the cytokine interleukin-1 beta, also showed increased expression, but with a different temporal profile from caspase-8. In contrast, caspase-9, which forms part of the pathway signalling through the mitochondria, showed a decrease in expression. The expression of a further four caspases (1, 2, 6 and 7) has also been characterised in a simpler experiment. These caspases all showed distinctive patterns of expression following the induction of ischemia. These data lead us to conclude that caspase expression as a whole is under very strict transcriptional control in this model. Certain elements of caspase signalling, such as the Fas-induced pathway and the events upstream of IL-1 beta processing, are upregulated, while others are not. This may be due to some form of genetic program activated in response to ischemia in the brain and may highlight which biological pathways are modulated.
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PMID:Caspase mRNA expression in a rat model of focal cerebral ischemia. 1131 84

Interleukin-10 (IL-10) has been shown to reduce neuronal degeneration after CNS injury. However, the molecular mechanisms underlying the neuroprotective properties of this cytokine are still under investigation. Glutamate exacerbates secondary injury caused by trauma. Thus, we examined whether IL-10 prevents glutamate-mediated cell death. We used rat cerebellar granule cells in culture because these neurons undergo apoptosis upon exposure to toxic concentrations of glutamate (100-500 microm) or NMDA (300 microm). Pretreatment of cerebellar granule cells with IL-10 (1-50 ng/ml) elicited a dose- and time-dependent reduction of glutamate-induced excitotoxicity. Most importantly, IL-10 reduced the number of apoptotic cells when added to the cultures together or 1 hr after glutamate. Using patch-clamping and fluorescence Ca(2+) imaging techniques, we examined whether IL-10 prevents glutamate toxicity by blocking the function of NMDA channel. IL-10 failed to affect NMDA channel properties and to reduce NMDA-mediated rise in intracellular Ca(2+). Thus, this cytokine appears to prevent glutamate toxicity by a mechanism unrelated to a blockade of NMDA receptor function. Various proteases, such as caspase-3, and transcription factors, such as nuclear factor kappaB (NF-kappaB), have been proposed to participate in glutamate-mediated apoptosis. Thus, we examined whether IL-10 modulates the activity of these apoptotic markers. IL-10 blocked both the glutamate-mediated induction of caspase-3 as well as NF-kappaB DNA binding activity, suggesting that the neuroprotective properties of IL-10 may rely on its ability to block the activity of proapoptotic proteins.
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PMID:Interleukin-10 prevents glutamate-mediated cerebellar granule cell death by blocking caspase-3-like activity. 1131 95

Cerebellar granule neurons (CGN) cultured in the presence of serum and depolarizing potassium concentrations undergo apoptosis when switched to serum-free medium containing physiological potassium concentrations. Here we show that processing of the key protease, caspase-3, depends on the activation of caspase-9, but not of caspase-8. Selective peptide inhibitors of caspase-9 block processing of caspase-3 and caspase-8 and inhibit apoptosis, whereas a selective inhibitor of caspase-8 blocks neither processing of caspase-3 nor cell death. The data obtained with peptide inhibitors were confirmed by adenovirally mediated ectopic expression of the cytokine response modifier A (crmA), the baculovirus protein p35, and the X chromosome-linked inhibitor of apoptosis (XIAP). Further, caspase-8-activating death receptors do not mediate apoptosis in CGN and potassium withdrawal-induced apoptosis evolves unaltered in gld or lpr mice, which harbor mutations in the CD95/CD95 ligand system. Thus, neuronal apoptosis triggered by potassium deprivation is death receptor-independent but involves the mitochondrial pathway of caspase activation.
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PMID:Cascade of caspase activation in potassium-deprived cerebellar granule neurons: targets for treatment with peptide and protein inhibitors of apoptosis. 1131 7

The death of T lymphocytes following their activation involves several signal pathways that converge on a series of proteases, known as caspases, that degrade cellular proteins and activate a DNAse. Caspases are activated through ligation of cell surface death receptors as well as via direct activation of downstream caspases, often through metabolic stress such as cytokine withdrawal or generation of oxygen radicals, that culminates in mitochondrial dysfunction and release of the pro-apoptotic molecules, cytochrome c and Smac/DIABLO. The Bcl-2 family members serve to regulate the mitochondrial membrane integrity. Recent studies are now revealing the significant contribution to the activation-induced cell death of T cells by downstream caspases such as caspase-3 and Bcl-2-homology domain 3 (BH3)-only members of the Bcl-2 family.
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PMID:Activation-induced cell death. 1140 69


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