Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.36 (caspase-1)
 6,285 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peripheral macrophages infiltrating the central nervous system and resident microglia phagocytize myelin in cell-mediated demyelinating diseases, including experimental autoimmune encephalomyelitis and multiple sclerosis. A cascade of cytokines is believed to modulate the immunological sequence of events occurring in these conditions, and several of these mediate their effects through the protein kinase C pathway. Therefore, we compared the effects of phorbol myristate acetate (PMA), an activator of protein kinase C, on various functions of cultured macrophages and microglia. PMA at moderate concentrations induced apoptosis in macrophages, and this process appeared to be increased in the presence of myelin. In contrast, microglia were activated by PMA, and greatly increased their phagocytosis of myelin. Control macrophages released a considerable amount of proteolytic activity into the medium, as measured by the breakdown of myelin basic protein, and in the process of undergoing apoptosis from PMA-treatment, even higher amounts were released. The enzyme activity in control macrophage medium was inhibited mainly by PMSF and calpain inhibitors, while that from PMA-treated macrophages was inhibited by calpain inhibitors only. An ICE inhibitor was ineffective in inhibiting activity in medium from PMA-treated cells undergoing apoptosis. Medium from microglia contained very little proteolytic activity, and this was not increased by PMA. Cultured macrophages showed little evidence of oxygen free radical release as measured by the TBARS procedure, and PMA had no effect. Microglia, on the other hand, produced higher levels of reactive oxygen species, with a further increase of 18% by PMA. Thus major functions of these phagocytic cells appear to be modulated by the protein kinase C pathway, although the two cell types show very different responses to an activator of this signal.
 ...
PMID:Effects of phorbol myristate acetate (PMA) on functions of macrophages and microglia in vitro. 948 57

As previously described, confluent AKR-2B fibroblasts rapidly disintegrate upon removal of serum. Platelet-derived growth factor isoforms AB or BB (PDGF-AB, -BB) added immediately after serum deprivation caused complete survival of the cells without initiating proliferation (Simm et al., 1994, J. Cell. Physiol. 160, 295). Here the role of cAMP as a protective agent was investigated by using forskolin or 8-Br-cAMP. Both reagents afforded high cellular protection. The phorbolester TPA, an activator of protein kinase C isoforms, also exerted a high protection against cell death (ED50 = 7 nM). Unexpectedly colchicine (ED50 = 1.5 microM) an inhibitor of tubulin polymerization also protected cells from death. The protective effects of PDGF-BB and TPA were dependent on protein synthesis as indicated by their complete suppression by cycloheximide (CHx). Surprisingly, forskolin and 8-Br-cAMP remained effective even in the presence of CHx. Detailed studies of several signalling pathways were performed. These investigations showed no interference between PDGF-BB and cAMP-dependent pathways at the early stage of signal transduction. As previously described, the ICE-like protease inhibitor tyr-val-ala-asp-chloromethylketone (YVAD-cmk) protected cells from death (Simm et al., 1997, J. Cell Sci. 110, 819-828). As shown here, a substantial protection was also achieved by the addition of two other caspase inhibitors: asp-glu-val-asp-aldehyde (DEVD-cho; ED50 = 100 microM) and benzoylcarbonyl-asp-glu-val-asp-chloromethylketone (Z-DEVD-cmk; ED50 = 100 microM). The activity of caspases was studied using either tyr-val-ala-asp-aminomethylcoumarine (YVAD-amc) or asp-glu-val-asp-aminomethylcoumarine (DEVD-amc) as substrates. There was no activation of a YVADase, whereas as pronounced increase in DEVDase activity was found with a maximum 3 h after serum removal. Cross competition experiments in vitro showed that the latter activity is inhibited also by low concentrations of YVAD-cmk (300-600 nM), suggesting that both inhibitors inactivated the same target protease. Remarkably all tested protective reagents lead to an inhibition of the DEVDase activity in intact cells. Since these reagents act via distinct intracellular pathways, the existence of a regulatory element upstream of the DEVDase is proposed which integrates signals from a variety of pathways.
 ...
PMID:Multiple intracellular pathways interfere with the activation of a CPP32-like protease induced by serum deprivation of AKR-2B cells. 957 Sep 18

Sphingosine and other long-chain bases (including sphinganine, dimethylsphingosine and stearylamine), but not octylamine (a short-chain analogue of sphinganine), induced apoptosis in Hep3B hepatoma cells. Because both D- and L-erythrosphingosine and stearylamine exert potent apoptotic effects on Hep3B cells, it is possible that these long-chain bases may activate apoptosis by inhibiting protein kinase C (PKC) activity. However, pretreatment with the PKC activator PMA could not rescue cells from apoptosis triggered by long-chain bases. Therefore the involvement of PKC in this apoptotic process requires further characterization. We also investigated whether these long-chain bases might be metabolized into ceramide in order to elicit their apoptotic action. We found that long-chain bases acted independently of ceramide in the induction of apoptosis, since addition of fumonisin B1, a fungal agent which effectively inhibits ceramide synthesis from sphingosine, did not protect against apoptosis. Additionally, we found that sphingosine-induced apoptosis was accompanied by activation of caspases. The functional role of caspases in this apoptotic process was examined by using specific caspase inhibitors. The general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone, which exhibits a broad specificity for caspase-family proteases, effectively blocked sphingosine-induced apoptosis. Furthermore, our results indicate that caspase-3-like proteases, but not caspase-1, are activated during apoptosis triggered by sphingosine. Enhancement of caspase-3-like activity and cleavage of poly(ADP-ribose) polymerase, an in vivo substrate for caspase-3, was clearly demonstrated in sphingosine-treated Hep3B cells. Considered together, these results suggest that caspase-3-like proteases participate in apoptotic cell death induced by sphingosine.
 ...
PMID:Activation of caspase-3-like proteases in apoptosis induced by sphingosine and other long-chain bases in Hep3B hepatoma cells. 993 12

The purpose of the present study was to study the mechanisms involved in the induction of apoptosis and by tributyltin (TBT) in rainbow trout hepatocytes, and to examine the role of intracellular Ca2+, protein kinase C (PKC) and proteases in the apoptotic process. The intracellular Ca2+ chelator BAPTA-AM has a suppressive effect on TBT-mediated apoptosis. However, exposure to the ionophore A23187 is not sufficient to induce apoptosis in trout hepatocytes. The results obtained also show that TBT stimulates PKC gamma and delta translocation from cytosol to the plasma membrane in trout hepatocytes after 30 min of exposure. However, PKC gamma translocation is down-regulated after 90 min of treatment. The addition of protein kinase inhibitors (staurosporine and H-7) not only fails to inhibit apoptosis induced by TBT, but also leads to enhancement of DNA fragmentation. These inhibitors also afford a remarkable protection against the loss of plasma membrane integrity caused by TBT exposure. PMA, a direct activator of PKC, fails to stimulate DNA fragmentation. In addition, Z-VAD.FMK is an extremely potent inhibitor of TBT-induced apoptosis in trout hepatocytes, indicating that the activation of ICE-like proteases is a key event in this process. The cysteine protease inhibitor N-ethylmaleimide also prevented TBT-induced DNA fragmentation. Taken together, these data allow for the first time to suggest a mechanistic model of TBT-induced apoptosis. We propose that TBT could trigger apoptosis through a step involving Ca2+ efflux from the endoplasmic reticulum or other intracellular pools and by mechanisms involving cysteine proteases, such as calpains, as well as the phosphorylation status of apoptotic proteins such as Bcl-2 homologues.
 ...
PMID:Tributyltin triggers apoptosis in trout hepatocytes: the role of Ca2+, protein kinase C and proteases. 999 Feb 99

Apoptosis was induced in human glioma cell lines by exposure to 100 nM calphostin C, a specific inhibitor of protein kinase C. Calphostin C-induced apoptosis was associated with synchronous down-regulation of Bcl-2 and Bcl-xL as well as activation of caspase-3 but not caspase-1. The exposure to calphostin C led to activation of stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK) and p38 kinase and concurrent inhibition of extracellular signal-regulated kinase (ERK). Upstream of ERK, Shc was shown to be activated, but its downstream Raf1 and ERK were inhibited. The pretreatment with acetyl-Tyr-Val-Ala-Asp-aldehyde, a relatively selective inhibitor of caspase-3, or benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD.fmk), a broad spectrum caspase inhibitor, similarly inhibited calphostin C-induced activation of SAPK/JNK and p38 kinase as well as apoptotic nuclear damages (chromatin condensation and DNA fragmentation) and cell shrinkage, suggesting that caspase-3 functions upstream of SAPK/JNK and p38 kinase, but did not block calphostin C-induced surface blebbing and cell death. On the other hand, the inhibition of SAPK/JNK by transfection of dominant negative SAPK/JNK and that of p38 kinase by SB203580 induced similar effects on the calphostin C-induced apoptotic phenotypes and cell death as did z-VAD.fmk and acetyl-Tyr-Val-Ala-Asp-aldehyde, but the calphostin C-induced PARP cleavage was not changed, suggesting that SAPK/JNK and p38 kinase are involved in the DNA fragmentation pathway downstream of caspase-3. The present findings suggest, therefore, that the activation of SAPK/JNK and p38 kinase is dispensable for calphostin C-mediated and z-VAD.fmk-resistant cell death.
 ...
PMID:Activation of stress-activated protein kinase/c-Jun NH2-terminal kinase and p38 kinase in calphostin C-induced apoptosis requires caspase-3-like proteases but is dispensable for cell death. 1002 38

The dihydrochalcone phloretin induced apoptosis in B16 mouse melanoma 4A5 cells and HL60 human leukemia cells. Phloretin was suggested to induce apoptosis in B16 cells mainly through the inhibition of glucose transmembrane transport. The phloretin-induced apoptosis in B16 cells was inhibited by actinomycin D, Ac-YVAD-CHO caspase-1-like inhibitor, and Ac-DEVD-CHO caspase-3-like inhibitor. During the induction of apoptosis by phloretin, the expression of Bax protein in B16 cells increased and the levels of p53, Bcl-2, and Bcl-XL proteins did not change. Our results suggested that phloretin induced apoptosis through the promotion of Bax protein expression and caspases activation. On the other hand, phloretin may induce apoptosis in HL60 cells through the inhibition of protein kinase C activity because phloretin inhibited protein kinase C activity in HL60 cells more than that in B16 cells. The phloretin induced-apoptosis in HL60 cells was not inhibited by actinomycin D and the caspase-1-like inhibitor, but slightly inhibited by the caspase-3-like inhibitor. Phloretin reduced the level of caspase 3 protein in HL60 cells, but not the level of the Bcl-2 protein. Phloretin did not increase the level of Bax protein. Phloretin was suggested to induce apoptosis in HL60 cells through the inhibition of protein kinase C activity, followed by the pathway, which is different from that in B16 cells.
 ...
PMID:Phloretin-induced apoptosis in B16 melanoma 4A5 cells and HL60 human leukemia cells. 1036 85

Neutrophils undergo constitutive apoptosis when aged ex vivo. Recent studies have indicated roles for Fas/CD95 and the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase system in this process. We have investigated the role of protein kinase C (PKC) in neutrophil death. We show that there is proteolysis and activation of the novel isoform PKCdelta in aged neutrophils and that this process is accelerated by the addition of an agonistic Fas antibody. PKCdelta proteolysis occurs before the onset of any detectable features of apoptosis and pharmacologic inhibition of this enzyme inhibits neutrophil apoptosis. PKCdelta cleavage and activation is dependent on caspase-8/FADD-like interleukin-1beta converting enzyme (FLICE)-mediated processing of caspase-3/CPP32. Neutrophil survival is prolonged by the addition of broad spectrum (BD.fmk) or caspase-8 targeted (zIETD.fmk) peptide caspase inhibitors. Inhibition of PKCdelta does not prevent apoptosis triggered by factor withdrawal in immature hematopoietic cells, including normal human CD34(+) progenitors indicating that within a given lineage, the mechanisms of apoptosis may be differentiation-stage-specific. Ex vivo aging of neutrophils leads to the increasing production of reactive oxygen species and this is attenuated in cells treated with either caspase or PKCdelta inhibitors. Proteolytically activated PKCdelta acts as a molecular link between the Fas/CD95 receptor and the NADPH-oxidase system and plays a central role in regulating the process of neutrophil apoptosis.
 ...
PMID:Caspase-mediated proteolysis and activation of protein kinase Cdelta plays a central role in neutrophil apoptosis. 1038 25

The role of protein kinase C-beta (PKC-beta) in apoptosis induced by tumor necrosis factor (TNF)-alpha and anti-Fas monoclonal antibody (mAb) in the human myeloid HL-60 leukemia cell line was studied by using its variant HL-525, which is deficient in PKC-beta. In contrast to the parental HL-60 cells, HL-525 is resistant to TNF-alpha-induced apoptosis but sensitive to anti-Fas mAb-induced apoptosis. Both cell types expressed similar levels of the TNF-receptor I, whereas the Fas receptor was detected only in HL-525 cells. Transfecting the HL-525 cells with an expression vector containing PKC-beta reestablished their susceptibility to TNF-alpha-induced apoptosis. The apoptotic effect of TNF-alpha in HL-60 and the transfectants was abrogated by fumonisin, an inhibitor of ceramide generation, and by the peptide Ac-YVAD-BoMK, an inhibitor of caspase-1 and -4. Supplementing HL-525 cells with exogenous ceramides bypassed the PKC-beta deficiency and induced apoptosis, which was also restrained by the caspase-1 and -4 inhibitor. The apoptotic effect of anti-Fas mAb in HL-525 cells was abrogated by the antioxidants N-acetylcysteine and glutathione and by the peptide z-DEVD-FMK, an inhibitor of caspase-3 and -7. We suggest that TNF-alpha-induced apoptosis involves PKC-beta and then ceramide and, in turn, caspase-1 and/or -4, whereas anti-Fas mAb-induced apoptosis utilizes reactive oxygen intermediates and, in turn, caspase-3 and/or -7.
 ...
PMID:Involvement of protein kinase C-beta and ceramide in tumor necrosis factor-alpha-induced but not Fas-induced apoptosis of human myeloid leukemia cells. 1043 32

Histone phosphorylation was investigated in several mammalian cells undergoing apoptosis (human HL-60 and HeLa, mouse FM3A and N18 cells, and rat thymocytes). Among the four nucleosomal core histones (H2A, H2B, H3, and H4), H2B, which is not usually phosphorylated in quiescent or growing cells, was found to be phosphorylated after treatment with various apoptotic inducers. The H2B was phosphorylated around the time when nucleosomal DNA fragmentation was initiated and, like this fragmentation, was completely blocked with Z-Asp-CH(2)-DCB, an inhibitor of ICE or ICE-like caspase. The involved single phosphopeptide of H2B proved to be phosphorylatable in vitro with a protein kinase C, and the site Ser-32 was tentatively identified. Despite typical apoptotic chromatin condensation, the H3 phosphorylation was at a low level, and the sites where phosphorylation did occur did not include any mitosis-specific phosphopeptides. Phosphorylation of H4 was increased, but the other two histone proteins (H1 and H2A) were not appreciably changed. These observations imply that 1) H2B phosphorylation occurs universally in apoptotic cells and is associated with apoptosis-specific nucleosomal DNA fragmentation, 2) chromatin condensation in apoptosis occurs by a different biochemical mechanism from those operating during mitosis or premature chromosome condensation, and 3) this unique phosphorylation of H2B is a useful biochemical hallmark of apoptotic cells.
 ...
PMID:Histone H2B phosphorylation in mammalian apoptotic cells. An association with DNA fragmentation. 1061 36

Caspases play crucial roles in the inflammatory response and in the cell pathway leading to apoptosis. Caspase 1 (ICE), 2 (Nedd2), 3 (CPP32), 6 (Mch2) and 8 (Mch5, FLICE) expression was examined using immunohistochemistry in the brains of rats and gerbils following systemic administration of kainic acid (KA). The distribution of caspase expression was compared with the distribution of c-Fos expression, a transcription factor that is produced in response to the excitotoxic insult. Strong caspase 2 immunoreactivity was found in microglia up to 6 h following KA administration. Focal strong expression of caspases 1, 2, 3, 6 and 8 was observed in astrocytes and neurons, from 12 to 48 h after KA injection, in areas in which a number of neurons were committed to die. This distribution was in contrast with the generalised distribution of c-Fos expression following KA administration. Only a minority of neurons in the entorhinal cortex, amygdala and hilus, but a majority of neurons in selected thalamic nuclei, exhibited strong caspase expression in KA-treated rats. Similar findings, although minimised, were observed in KA-treated gerbils. Double-labelling caspase immunohistochemistry and in situ end-labelling of nuclear DNA fragmentation disclosed co-localisation of strong caspase expression and nuclear DNA breaks in a small percentage of neurons but no co-localisation in astrocytes. Western blots of entorhinal cortex and neocortex homogenates showed cleavage of certain caspase substrates in KA-treated rats. The intensity of the bands corresponding to lamin B and protein kinase C-delta was decreased in the entorhinal cortex following KA administration. Several bands appeared in the entorhinal cortex and neocortex paragraph signin Western blots processed for the demonstration of poly(ADP-ribose) polymerase (PARP), thus indicating that other proteases, in addition to caspases, cleaved PARP following KA administration. Taken together, these findings indicate that KA excitotoxicity triggers caspase expression which, although predominant in regions subjected to irreversible cell damage, has only a weak association with the presence of nuclear DNA breaks and neuron cell death. Although these results suggest caspase activation, further studies have to be performed to elucidate whether caspase activation plays a crucial role in KA excitotoxicity.
 ...
PMID:Differential c-Fos and caspase expression following kainic acid excitotoxicity. 1066 66


1 2 Next >>