Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasmalopsychosine, a characteristic fatty aldehyde conjugate of beta-galactosylsphingosine (psychosine) found in brain white matter, enhances p140trk (Trk A) phosphorylation and mitogen-activated protein kinase (MAPK) activity and as a consequence induces neurite outgrowth in PC12 cells. The effect of plasmalopsychosine on neurite outgrowth and its prolonged activation of MAPK was similar to that of nerve growth factor (NGF), and the effect was specific to neuronal cells. Plasmalopsychosine was not capable of competing with cold chase-stable, high affinity binding of NGF to Trk A, indicating that plasmalopsychosine and NGF differ in terms of Trk A-activating mechanism. Tyrosine kinase inhibitors K-252a and staurosporine, known to inhibit the neurotrophic effect of NGF, also inhibited these effects of plasmalopsychosine, suggesting that plasmalopsychosine and NGF share a common signaling cascade. Plasmalopsychosine prevents apoptosis of PC12 cells caused by serum deprivation, indicating that it has "neurotrophic factor-like" activity. Taken together, these findings indicate that plasmalopsychosine may play an important role in development and maintenance of the vertebrate nervous system.
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PMID:Plasmalopsychosine of human brain mimics the effect of nerve growth factor by activating its receptor kinase and mitogen-activated protein kinase in PC12 cells. Induction of neurite outgrowth and prevention of apoptosis. 855 9

Inhibition of the major cytosolic protease, proteasome, has been reported to induce programmed cell death in several cell lines, while with other lines, similar inhibition blocked apoptosis triggered by a variety of harmful treatments. To elucidate the mechanism of pro- and antiapoptotic action of proteasome inhibitors, their effects on U937 lymphoid and 293 kidney human tumor cells were tested. Treatment with peptidyl aldehyde MG132 and other proteasome inhibitors led to a steady increase in activity of c-Jun N-terminal kinase, JNK1, which is known to initiate the apoptotic program in response to certain stresses. Dose dependence of MG132-induced JNK activation was parallel with that of apoptosis. Furthermore, inhibition of the JNK signaling pathway strongly suppressed MG132-induced apoptosis. These data indicate that JNK is critical for the cell death caused by proteasome inhibitors. An antiapoptotic action of proteasome inhibitors could be revealed by a short incubation of cells with MG132 followed by its withdrawal. Under these conditions, the major heat shock protein Hsp72 accumulated in cells and caused suppression of JNK activation in response to certain stresses. Accordingly, pretreatment with MG132 reduced JNK-dependent apoptosis caused by heat shock or ethanol, but it was unable to block JNK-independent apoptosis induced by TNFalpha. Therefore, proteasome inhibitors activate JNK, which initiates an apoptotic program, and simultaneously they induce Hsp72, which suppresses JNK-dependent apoptosis. A balance between these two effects might define the fate of cells exposed to the inhibitors.
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PMID:Proteasome inhibitors activate stress kinases and induce Hsp72. Diverse effects on apoptosis. 949 67

Nitric oxide (NO) induction through the inducible NO synthase has been demonstrated to cause cell death in macrophages. We demonstrate that, in macrophages that have been rendered resistant to apoptosis induced by inducible NO synthase (RES cells), exposure to exogenous NO donors results in a hypersensitive apoptosis reaction when compared with the parental RAW 264.7 cells. The apoptosis induced via exogenous NO donors was found to be caspase 3-independent. Although caspase 3 activity was stimulated in the apoptotic macrophages, inhibition of caspase 3 by the inhibitor DEVD-CHO (N-acetyl-Asp-Glu-Val-Asp-aldehyde) did not reverse the apoptosis induced by the NO donor S-nitrosoglutathione (GSNO). This suggests that although caspase 3 activity is stimulated during apoptosis in macrophages, this signal is not sufficient to induce apoptosis. Cleavage of the enzyme poly(ADP ribose) polymerase mirrors our results of the caspase activity. Interestingly, we show that exogenous NO donation results in an accumulation of cells at the G2/M-phase border. Here, we demonstrate that the mitogen activated protein kinase kinase (MEK) inhibitor PD 098059 can be used to reverse the G2/M-phase block and show that this treatment also inhibits the observed apoptosis in RES macrophages. Treatment with the MEK inhibitor also reversed both the caspase 3 activity and poly(ADP ribose) polymerase cleavage in cells treated with GSNO. This result indicates that the mitogen-activated protein kinase pathway may be involved in regulation of the caspase cascade. Alternatively, it may suggest an activity for the MEK inhibitor heretofore not observed, that of a cyclin kinase inhibitor. Our results suggest that selection of macrophages by resistance to endogenously generated NO may cause hypersensitivity to exogenous NO donors. These findings have relevant implications for the treatment of apoptotic-resistant cell populations that may occur in both cancer and atheroma.
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PMID:Macrophages resistant to endogenously generated nitric oxide-mediated apoptosis are hypersensitive to exogenously added nitric oxide donors: dichotomous apoptotic response independent of caspase 3 and reversal by the mitogen-activated protein kinase kinase (MEK) inhibitor PD 098059. 956 Feb 25

Although the available evidence suggests that whereas the caspase family plays a major role in apoptosis, they are not the sole stimulators of death. A random yeast two-hybrid screen of a lymphocyte cDNA library (using caspase-3 as the bait) found an interaction between caspase-3 and the regulatory subunit Aalpha of protein phosphatase 2A. This protein was found to be a substrate for caspase-3, but not caspase-1, and could compete effectively against either a protein or synthetic peptide substrate. In Jurkat cells induced to undergo apoptosis with anti-Fas antibody, protein phosphatase 2A (PP2A) activity increased 4.5-fold after 6 h. By 12 h, the regulatory Aalpha subunit could no longer be detected in cell lysates. There was no change in the amount of the catalytic subunit. The effects on PP2A could be prevented by the caspase family inhibitors acetyl-Asp-Glu-Val-Asp (DEVD) aldehyde or Ac-DEVD fluoromethyl ketone. The mitogen-activated protein (MAP) kinase pathway is regulated by PP2A. At 12 h after the addition of anti-Fas antibody, a decrease in the amount of the phosphorylated forms of MAP kinase was observed. Again, this loss of activated MAP kinase could be prevented by the addition of DEVD-cho or DEVD-fmk. These data are consistent with a pathway whereby induction of apoptosis activates caspase-3. This enzyme then cleaves the regulatory Aalpha subunit of PP2A, increasing its activity. These data show that the activated PP2A will then effect a change in the phosphorylation state of the cell. These data provide a link between the caspases and signal transduction pathways.
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PMID:Regulation of protein phosphatase 2A activity by caspase-3 during apoptosis. 958 51

Benzo(a)pyrene (BaP), a prototype of polycyclic aromatic hydrocarbons (PAHs), is a potent procarcinogen generated during the combustion of fossil fuels and cigarette smoke. In addition to the carcinogenic and mutagenic effects, BaP and other PAHs, including 7,12-dimethylbenz[a]anthracene and 2,3,7,8-tetrachlorodibenzo[p]dioxin, have been shown to induce programmed cell death or apoptosis. However, the molecular mechanisms by which PAHs such as BaP induce apoptosis are not clear. To investigate the molecular events leading to apoptosis induced by BaP, we studied the involvement of the interleukin 1beta-converting enzyme (ICE)/Ced-3 family of proteases (caspases) and c-Jun NH2-terminal kinase 1 (JNK1), which have been shown to mediate numerous extracellular stimuli-induced apoptosis. On treatment of mouse Hepa 1c1c7 hepatoma cells with BaP, the induction of apoptosis, as determined by genome digestion, was observed at concentrations of 1-30 microM after 24 h of treatments. Importantly, at the apoptosis-inducing concentrations, BaP also induced the activation of an ICE/Ced-3 cysteine protease caspase-3 but not caspase-1 (ICE). The activation of caspase-3 by BaP preceded apoptosis. Furthermore, a specific inhibitor of caspase-3-like proteases, acetyl-Asp-Glu-Val-Asp-aldehyde, significantly blocked caspase-3 activity and attenuated apoptosis induced by BaP. Treatment with BaP also caused a time- and dose-dependent activation of JNK1 activity. Interestingly, a much lower concentration (5 nM), as well as much earlier kinetics, were observed in JNK1 activation as compared with caspase-3 activation or induction of apoptosis by BaP. In summary, our results demonstrate that BaP induced apoptosis in the mouse hepatoma Hepa1c1c7 cell line via a caspase-dependent pathway, which may be independent of JNK activation.
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PMID:Induction of apoptosis and activation of interleukin 1beta-converting enzyme/Ced-3 protease (caspase-3) and c-Jun NH2-terminal kinase 1 by benzo(a)pyrene. 960 52

The ATP/ubiquitin-dependent 26S proteasome is a central regulator of cell cycle progression and stress responses. While investigating the application of peptide aldehyde proteasome inhibitors to block signal-induced IkappaBalpha degradation in human LNCaP prostate carcinoma cells, we observed that persistent inhibition of proteasomal activity signals a potent cell death program. Biochemically, this program included substantial upregulation of PAR-4 (prostate apoptosis response-4), a putative pro-apoptotic effector protein and stabilization of c-jun protein, a potent pro-death effector in certain cells. We also observed modest downregulation of bcl-XL, a pro-survival effector protein. However, in contrast to some recent reports stable, high level, expression of functional bcl-2 protein in prostate carcinoma cells failed to signal protection against cell death induction by proteasome inhibitors. Also in disagreement to a recent report, no evidence was found for activation of the JNK stress kinase pathway. A role for p53, a protein regulated by the proteasome pathway, was ruled out, since comparable cell death induction by proteasome inhibitors occurred in PC-3 cells that do not express functional p53 protein. These data signify that the ubiquitin/proteasome pathway represents a potential therapeutic target for prostate cancers irrespective of bcl-2 expression or p53 mutations.
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PMID:Prostate carcinoma cell death resulting from inhibition of proteasome activity is independent of functional Bcl-2 and p53. 987 95

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.
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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

PC12 cells are well characterized for their ability to differentiate into neuronal-like cells when challenged with nerve growth factor. It has been reported that the calpain and proteasome inhibitor N-acetyl-Leu-Leu-norleucinal (CI) is also able to induce neurite outgrowth in PC12 cells. In this study, we report that the inhibitor of proteasomal chymotrypsin-like activity, carbobenzoxy-Ile-Glu-(O-tert-butyl)-Ala-Leu-aldehyde (PSI), can also induce differentiation of PC12 cells. Induction of neurite outgrowth with PSI, CI, or its close analogue, carbobenzoxy-Leu-Leu-leucinal (MG132), was associated with stress-activated protein kinase (SAPK) activation. Neurite formation induced by protease inhibition was independent of mitogen-activated protein kinase/extracellular signal-regulated kinase, p38/reactivating kinase, or phosphatidylinositol 3-kinase activities. The exact mechanism by which protease inhibition activates SAPKs remains to be elucidated; however, our results suggest that the SAPK signal transduction cascade may be an alternative and/or parallel pathway in the regulation of neuronal differentiation.
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PMID:Activation of stress-activated protein kinases correlates with neurite outgrowth induced by protease inhibition in PC12 cells. 1003 79

The complete sequencing of the genome of Saccharomyces cerevisiae indicated that this organism contains five genes encoding aldehyde dehydrogenases. YOR374w and YER073w correspond to the mitochondrial isoforms and we propose as gene names ALD4 and ALD5, respectively. YPL061w has been described as the cytoplasmic constitutive isoform and named ALD6. We characterize here the tandem-repeated ORFs YMR170c and YMR169c as the cytoplasmic stress-inducible isoforms, with gene names ALD2 and ALD3, respectively. The expression of ALD2 and ALD3 is dependent on the general-stress transcription factors Msn2,4 but independent of the HOG MAP kinase pathway. ALD3 is induced by a variety of stresses, including osmotic shock, heat shock, glucose exhaustion, oxidative stress and drugs. ALD2 is only induced by osmotic stress and glucose exhaustion. A double null mutant, ald2 ald3, exhibited unchanged sensitivity to any of the above stresses. The only phenotype detected in this mutant was a reduced growth rate in ethanol medium as compared to the wild type.
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PMID:A proposal for nomenclature of aldehyde dehydrogenases in Saccharomyces cerevisiae and characterization of the stress-inducible ALD2 and ALD3 genes. 1040 63

The transcription factor activator protein-1 (AP-1) is activated in response to physiological activity in neuronal circuits and in response to neuronal injury associated with various acute and chronic neurodegenerative conditions. The membrane lipid peroxidation product 4-hydroxy-2,3-nonenal (HNE) is increasingly implicated in the disruption of neuronal calcium homeostasis that occurs in various paradigms of neuronal excitotoxicity and apoptosis. The possible mechanistic links between lipid peroxidation and alterations in gene transcription during neuronal apoptosis have not previously been examined. We now report that exposure of cultured rat cortical neurons to an apoptotic concentration of HNE results in a large increase in AP-1 DNA-binding activity. The protein synthesis inhibitor cycloheximide blocked the induction of AP-1, consistent with a requirement for induction of expression of AP-1 family members. The broad-spectrum caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone and the caspase-3 inhibitor N-acetyl-Asp-Glu-Val-Asp-aldehyde blocked HNE-induced increases in AP-1 DNA-binding activity, demonstrating a requirement for caspase activation in the activation of AP-1. HNE induced phosphorylation of c-Jun N-terminal kinase (JNK), which was prevented by caspase inhibitors, indicating that HNE was acting at or upstream of JNK phosphorylation. The intracellular calcium chelator BAPTA-acetoxymethyl ester completely prevented stimulation of AP-1 DNA-binding by HNE, indicating a requirement for calcium. Moreover, agents that suppress mitochondrial calcium uptake (ruthenium red) and membrane permeability transition (cyclosporin A) attenuated AP-1 activation by HNE, suggesting a contribution of mitochondrial alterations to AP-1 activation. Collectively, our data suggest a scenario in which HNE disrupts neuronal calcium homeostasis and perturbs mitochondrial function, resulting in caspase activation. Activated caspases, in turn, induce activation of JNK, resulting in stimulation of AP-1 DNA-binding protein production. This transcriptional pathway induced by HNE may modulate the cell death process.
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PMID:The lipid peroxidation product 4-hydroxy-2,3-nonenal increases AP-1-binding activity through caspase activation in neurons. 1061 17


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