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: UNIPROT:P42574 (caspase-3)
45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that primarily infects immunocompromised individuals and patients with cystic fibrosis. Using a tissue culture system, invasive strains of P. aeruginosa were discovered to induce apoptosis at high frequency in HeLa and other epithelial and fibroblast cell lines. This apoptotic phenotype in the infected cells was determined by several criteria including (i) visual changes in cell morphology, (ii) induction of chromatin condensation and nuclear marginalization, (iii) the presence of a high percentage of cells with subG1 DNA content, and (iv) activation of caspase-3 activity. Induction of the type III secretion machinery, but not invasion of P. aeruginosa is required for induction of apoptosis. The apoptosis phenotype is independent of the cytoskeletal rearrangements that occur in the host cell early after infection. Mutants in P. aeruginosa exoS fail to induce apoptosis and complementation with wild-type exoS restored the apoptosis-inducing capacity, demonstrating that ExoS is the effector molecule. Analysis of exoS activity mutants shows that the ADP-ribosylating capacity of ExoS is essential for inducing the apoptotic pathway.
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PMID:Pseudomonas aeruginosa mediated apoptosis requires the ADP-ribosylating activity of exoS. 1102 28

Pseudomonas aeruginosa is a gram-negative facultative opportunistic pathogen associated with severe infections in immunocompromised hosts and in patients with cystic fibrosis. P. aeruginosa strains show divergent pathogenicity in vivo and trigger apoptosis of and/or are internalized into human host cells. In the present study, we studied the molecular ordering of apoptosis signaling upon infection of human conjunctiva epithelial Chang cells with P. aeruginosa PAK as well as the role of bacterial pili in the response to the infection. Our results show that CD95 up-regulation is followed by early activation of caspase-8 and -3 and cleavage of the caspase-3 substrate poly(ADP-ribose) polymerase. The data also demonstrate release of apoptosis inducing factor into the cytosol of infected cells. Induction of mitochondrial alterations, i.e., mitochondrial depolarization and release of cytochrome c, as well as cleavage of caspase-9, -7, and -1 occurred only at later time points. In addition, our results demonstrate that pili are required for P. aeruginosa-induced apoptosis of human epithelial cells. While the two piliated P. aeruginosa strains, PAO-I and PAK, induced apoptosis of Chang cells within 3 h of infection, the pilus-deficient P. aeruginosa mutants PAK Delta pilA and PAK Delta pilA Delta all were without effect. The pilus-deficient mutants failed to induce a significant up-regulation of CD95 on the cell surface and to trigger mitochondrial alterations or activation of caspase-8, -3, and -7. In addition, only the piliated wild-type strains induced caspase-1-mediated activation of interleukin-1 beta. Thus, pili are necessary for distinct infection-induced cellular responses of human epithelial cells.
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PMID:Apoptotic response of Chang cells to infection with Pseudomonas aeruginosa strains PAK and PAO-I: molecular ordering of the apoptosis signaling cascade and role of type IV pili. 1270 41

As an opportunistic bacterial pathogen, Pseudomonas aeruginosa mainly affects immunocompromised individuals as well as patients with cystic fibrosis. In a previous study, we showed that ExoS of P. aeruginosa, when injected into host cells through a type III secretion apparatus, functions as an effector molecule to trigger apoptosis in various tissue culture cells. Here, we show that injection of the ExoS into HeLa cells activates c-Jun NH(2)-terminal kinase (JNK) phosphorylation while shutting down ERK1/2 and p38 phosphorylation. Inhibiting JNK activation by expression of a dominant negative JNK1 or with a specific JNK inhibitor abolishes ExoS-triggered apoptosis, demonstrating the requirement for JNK-mediated signaling. Following JNK phosphorylation, cytochrome c is released into the cytosol, leading to the activation of caspase 9 and eventually caspase 3. Although c-Jun phosphorylation is also observed as a result of JNK activation, ongoing host protein synthesis is not essential for the apoptotic induction, suggesting that c-Jun- or other AP-1-driven activation of gene expression is dispensable in this process. Therefore, ExoS has opposing effects on different cellular pathways that regulate apoptosis: it shuts down host cell survival signal pathways by inhibiting ERK1/2 and p38 activation, and it activates proapoptotic pathways through activation of JNK1/2 leading ultimately to cytochrome c release and activation of caspases. These results highlight the modulation of host cell signaling by the type III secretion system during interaction between P. aeruginosa and host cells.
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PMID:c-Jun NH2-terminal kinase-mediated signaling is essential for Pseudomonas aeruginosa ExoS-induced apoptosis. 1276 Nov 20

In the absence and in the resolution of inflammatory responses, neutrophils rapidly undergo spontaneous apoptosis. Here we report about a new apoptosis pathway in these cells that requires calpain-1 activation and is essential for the enzymatic activation of the critical effector caspase-3. Decreased levels of calpastatin, a highly specific intrinsic inhibitor of calpain, resulted in activation of calpain-1, but not calpain-2, in neutrophils undergoing apoptosis, a process that was blocked by a specific calpain-1 inhibitor or by intracellular delivery of a calpastatin peptide. Further support for the importance of the calpastatin-calpain system was obtained by analyzing neutrophils from patients with cystic fibrosis that exhibited delayed apoptosis, associated with markedly increased calpastatin and decreased calpain-1 protein levels compared with neutrophils from control individuals. Additional studies were designed to place calpain-1 into the hierarchy of biochemical events leading to neutrophil apoptosis. Pharmacological calpain inhibition during spontaneous and Fas receptor-induced neutrophil apoptosis prevented cleavage of Bax into an 18-kDa fragment unable to interact with Bcl-xL. Moreover, calpain blocking prevented the mitochondrial release of cytochrome c and Smac, which was indispensable for caspase-3 processing and enzymatic activation, both in the presence and absence of agonistic anti-Fas receptor antibodies. Taken together, calpastatin and calpain-1 represent critical proximal elements in a cascade of pro-apoptotic events leading to Bax, mitochondria, and caspase-3 activation, and their altered expression appears to influence the life span of neutrophils under pathologic conditions.
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PMID:Calpain-1 regulates Bax and subsequent Smac-dependent caspase-3 activation in neutrophil apoptosis. 1461 48

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine known to activate macrophages and T cells. In this study, we demonstrate that recombinant MIF delays apoptosis of neutrophils in vitro. MIF action is dose and time dependent as well as specific since it was abolished with a neutralizing anti-MIF antibody. MIF, like G-CSF, delayed cleavage of the proapoptotic members of the Bcl-2 family Bid and Bax in neutrophils, suggesting that MIF inhibits apoptosis pathways proximal to mitochondria activation. Indeed, MIF also prevented release of cytochrome c and Smac from the mitochondria and subsequent activation of the critical effector caspase-3 in these cells. Moreover, we observed increased MIF plasma levels in patients with cystic fibrosis, a heterogeneous recessive genetic disorder associated with bacterial infections and delayed neutrophil apoptosis. In conclusion, MIF is a survival cytokine for human neutrophils, a finding with potential pathologic relevance in infectious diseases.
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PMID:Macrophage migration inhibitory factor delays apoptosis in neutrophils by inhibiting the mitochondria-dependent death pathway. 1465 84

Lung epithelium in cystic fibrosis (CF) patients is characterized by structural damage and altered repair due to oxidative stress. To gain insight into the oxidative stress-related damage in CF, we studied the effects of hyperoxia in CF and normal lung epithelial cell lines. In response to a 95% O2 exposure, both cell lines exhibited increased reactive oxygen species. Unexpectedly, the cyclin-dependent kinase inhibitor p21WAF1/CIP1 protein was undetectable in CF cells under hyperoxia, contrasting with increased levels of p21WAF1/CIP1 in normal cells. In both cell lines, exposure to hyperoxia led to S-phase arrest. Apoptotic features including nuclear condensation, DNA laddering, Annexin V incorporation, and elevated caspase-3 activity were not readily observed in CF cells in contrast to normal cells. Interestingly, treatment of hyperoxia-exposed CF cells with two proteasome inhibitors, MG132 and lactacystin, restored p21WAF1/CIP1 protein and was associated with an increase of caspase-3 activity. Moreover, transfection of p21WAF1/CIP1 protein in CF cells led to increased caspase-3 activity and was associated with increased apoptotic cell death, specifically under hyperoxia. Taken together, our data suggest that modulating p21WAF1/CIP1 degradation may have the therapeutic potential of reducing lung epithelial damage related to oxidative stress in CF patients.
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PMID:Oxidative stress response results in increased p21WAF1/CIP1 degradation in cystic fibrosis lung epithelial cells. 1633 81

Pseudomonas aeruginosa infection is a serious complication in immunocompromised individuals and in patients with cystic fibrosis. We have previously shown that the type III secreted effector ExoS triggers apoptosis in various cultured cell lines via its ADP-ribosyltransferase (ADPRT) activity. The apoptosis process was further shown to involve intrinsic signalling pathway requiring c-Jun N-terminal kinase (JNK)-initiated mitochondrial pathway. In the present study, we investigated the role of Fas pathway activation in P. aeruginosa-induced apoptosis. P. aeruginosa infection resulted in caspase 8 cleavage in HeLa cells, which was inhibited by overexpression of a dominant negative version of Fas-associated death domain (FADD), suggesting that Fas pathway was activated. In fact, confocal laser scanning microscopy showed that P. aeruginosa induced clustering of FasR. In addition, the ADPRT activity of the ExoS was required for the induction of FasR clustering and caspase 8 cleavage. However, blocking the FasR-FasL interaction by antagonistic antibodies to FasR or to FasL had no effect on P. aeruginosa-induced caspase 8 and caspase 3 activation, neither did the silencing of FasR by small interfering RNA (siRNA), suggesting that caspase 8 activation through the FADD bypasses FasR/FasL-mediated signalling. Thus, FADD-mediated caspase 8 activation involves intracellular ExoS in an ADPRT-dependent manner. Furthermore, silencing of caspase 8 by siRNA did not interfere with P. aeruginosa-induced apoptosis, whereas it rendered HeLa cells markedly increased resistance towards FasL-induced apoptosis. In conclusion, our findings indicate that ExoS of P. aeruginosa induces apoptosis through a mechanism that is independent of Fas receptor/caspase 8 pathway.
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PMID:ExoS of Pseudomonas aeruginosa induces apoptosis through a Fas receptor/caspase 8-independent pathway in HeLa cells. 1644 42

Members of the family of calcium-activated chloride channels (CLCA) have been implicated as modulators of the phenotype in cystic fibrosis (CF). Here, the expression levels of the murine mCLCA1, mCLCA2, mCLCA3 and mCLCA4 were quantified by real-time RT-PCR in the small intestines of CF (cftr (tm1Cam), cftr (TgH(neoim)1Hgu)) and wild type C57BL/6, BALB/c, DBA/2 and NMRI mice. Markedly different expression levels of all four CLCA homologs were observed between the different wild type strains. Expression of mCLCA1 and mCLCA4 was similar in CF versus wild type. In contrast, mCLCA3 mRNA copy numbers were increased up to threefold in all CF models. Immunohistochemical detection of mCLCA3 and PAS reactions on consecutive tissue sections identified a similar increase in mCLCA3 expressing goblet cells, suggesting that elevated mRNA copy numbers of mCLCA3 are due to goblet cell hyperplasia rather than transcriptional regulatory events. Increased mCLCA2 mRNA copy numbers, however, were considered more likely to be due to transcriptional upregulation. Changes in mRNA copy numbers were not associated with altered cell kinetics as determined by immunohistochemistry using antibodies to phospho-histone 3 and activated caspase-3. The results suggest that both mCLCA2 and mCLCA3 may act as modifiers of the intestinal phenotype in CF.
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PMID:Differential expression of calcium-activated chloride channels (CLCA) gene family members in the small intestine of cystic fibrosis mouse models. 1651 48

Cystic fibrosis is a lethal inherited disorder caused by mutations in a single gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, resulting in progressive oxidative lung damage. In this study, we evaluated the role of CFTR in the control of ubiquitin-proteasome activity and nuclear factor (NF)-kappaB/IkappaB-alpha signaling after lung oxidative stress. After a 64-hour exposure to hyperoxia-mediated oxidative stress, CFTR-deficient (cftr(-/-)) mice exhibited significantly elevated lung proteasomal activity compared with wild-type (cftr(+/+)) animals. This was accompanied by reduced lung caspase-3 activity and defective degradation of NF-kappaB inhibitor IkappaB-alpha. In vitro, human CFTR-deficient lung cells exposed to oxidative stress exhibited increased proteasomal activity and decreased NF-kappaB-dependent transcriptional activity compared with CFTR-sufficient lung cells. Inhibition of the CFTR Cl(-) channel by CFTR(inh-172) in the normal bronchial immortalized cell line 16HBE14o- increased proteasomal degradation after exposure to oxidative stress. Caspase-3 inhibition by Z-DQMD in CFTR-sufficient lung cells mimicked the response profile of increased proteasomal degradation and reduced NF-kappaB activity observed in CFTR-deficient lung cells exposed to oxidative stress. Taken together, these results suggest that functional CFTR Cl(-) channel activity is crucial for regulation of lung proteasomal degradation and NF-kappaB activity in conditions of oxidative stress.
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PMID:Cystic fibrosis transmembrane conductance regulator controls lung proteasomal degradation and nuclear factor-kappaB activity in conditions of oxidative stress. 1837 27

The functional significance of the expression of cystic fibrosis transmembrane regulator (CFTR) on endothelial cells has not yet been elucidated. Since CFTR has been implicated in the regulation of intracellular sphingolipid levels, which are important regulators of endothelial cell apoptosis in response to various insults, we investigated the role of CFTR in the apoptotic responses of lung endothelial cells. CFTR was detected as a functional chloride channel in primary lung endothelial cells isolated from both pulmonary arteries (human or mouse) and bronchial arteries (sheep). Both specific CFTR inhibition with 2-(phenylamino) benzoic acid diphenylamine-2-carboxylic acid, 5-[(4-carboxyphenyl)methylene]-2-thioxo-3-[(3-trifluoromethyl)phenyl-4-thiazolidinone (CFTR(inh)-172), or 5-nitro-2-(3-phenylpropylamino)benzoic acid and CFTR knockdown significantly attenuated endothelial cell apoptosis induced by staurosporine or H(2)O(2). CFTR(inh)-172 treatment prevented the increases in the ceramide:sphingosine-1 phosphate ratio induced by H(2)O(2) in lung endothelial cells. Replenishing endogenous ceramides via sphingomyelinase supplementation restored the susceptibility of CFTR-inhibited lung endothelial cells to H(2)O(2)-induced apoptosis. Similarly, the anti-apoptotic phenotype of CFTR-inhibited cells was reversed by lowering the intracellular pH, and was reproduced by alkalinization before H(2)O(2) challenge. TUNEL staining and active caspase-3 immunohistochemistry indicated that cellular apoptosis was decreased in lung explants from patients with cystic fibrosis compared with those with smoking-induced chronic obstructive lung disease, especially in the alveolar tissue and vascular endothelium. In conclusion, CFTR function is required for stress-induced apoptosis in lung endothelial cells by maintaining adequate intracellular acidification and ceramide activation. These results may have implications in the pathogenesis of cystic fibrosis, where aberrant endothelial cell death may dysregulate lung vascular homeostasis, contributing to abnormal angiogenesis and chronic inflammation.
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PMID:CFTR regulation of intracellular pH and ceramides is required for lung endothelial cell apoptosis. 1916 2


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