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:2.4.2.30 (PARP)
13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Fas/APO-1/CD95 ligand (CD95L) and the recently cloned TRAIL ligand belong to the TNF-family and share the ability to induce apoptosis in sensitive target cells. Little information is available on the degree of functional redundancy between these two ligands in terms of target selectivity and intracellular signalling pathway(s). To address these issues, we have expressed and characterized recombinant mouse TRAIL. Specific detection with newly developed rabbit anti-TRAIL antibodies showed that the functional TRAIL molecule released into the supernatant of recombinant baculovirus-infected Sf9 cells is very similar to that associated with the membrane fraction of Sf9 cells. CD95L resistant myeloma cells were found to be sensitive to TRAIL, displaying apoptotic features similar to those of the CD95L- and TRAIL-sensitive T leukemia cells Jurkat. To assess if IL-1beta-converting enzyme (ICE) and/or ICE-related proteases (IRPs) (caspases) are involved in TRAIL-induced apoptosis of both cell types, peptide inhibition experiments were performed. The irreversible IRP/caspase-inhibitor Ac-YVAD-cmk and the reversible IRP/caspase-inhibitor Ac-DEVD-CHO blocked the morphological changes, disorganization of plasma membrane phospholipids, DNA fragmentation, and loss of cell viability associated with TRAIL-induced apoptosis. In addition, cells undergoing TRAIL-mediated apoptosis displayed cleavage of poly(ADP)-ribose polymerase (PARP) that was completely blocked by Ac-DEVD-CHO. These results indicate that TRAIL seems to complement the activity of the CD95 system as it allows cells, otherwise resistant, to undergo apoptosis triggered by specific extracellular ligands. Conversely, however, induction of apoptosis in sensitive cells by TRAIL involves IRPs/caspases in a fashion similar to CD95L. Thus, differential sensitivity to CD95L and TRAIL seems to map to the proximal signaling events associated with receptor triggering.
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PMID:Interleukin 1 beta-converting enzyme related proteases/caspases are involved in TRAIL-induced apoptosis of myeloma and leukemia cells. 910 50

Cleavage of poly-(ADP-ribose) polymerase is a process occurring early during the execution phase of apoptosis. Although in many experimental systems PARP cleavage indicates a point of no return, the significance of this proteolytic step for apoptosis remains unclear. Here we compare the susceptibility of cells from wild-type mice and PARP-/- mice to several inducers of apoptosis. Neither the susceptibility of hepatocytes towards CD95 or TNF-mediated apoptosis nor the activation of PARP-cleaving caspases was modified in PARP-/- liver cells. Thymocytes with either genotype exhibited similar sensitivity to treatments with ceramide, dexamethasone, or etoposide. The sensitivity of primary neurons towards apoptosis induced by staurosporine, colchicine, potassium withdrawal, peroxynitrite, or the neurotoxin MPP+ was also unaltered. These data suggest that neither activation nor cleavage of PARP has a causal role in apoptotic cell death of primary, non-transformed cells.
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PMID:Apoptosis in the absence of poly-(ADP-ribose) polymerase. 914 69

Aging is characterized by increased T cell lymphopenia, T cell dysfunction, and increased serum TNF levels. In this study, we have examined the role of TNF-induced apoptosis in T cell deficiency in lymphocytes from aged humans. The constitutive expression of TNF receptors (TNFRI and TNFRII) and the adapter molecules, including TNFR-associated death domain protein (TRADD), TNFR-associated factor 2 (TRAF-2), and receptor interacting protein (RIP), were analyzed both at the protein level by flow cytometry or Western blotting, and at the mRNA level using quantitative PCR or Northern blotting in lymphocytes from aged and young subjects. The susceptibility of T cells to undergo TNF-induced apoptosis was analyzed using terminal deoxynucleotidyltransferase-mediated UTP-end-labeling (TUNEL) and DNA ladder assays. Caspase (caspase-8 and caspase-3) activation was compared between aged and young subjects using Western blotting and colorimetric assays. In lymphocytes from aged humans, there was an increased susceptibility of CD4+ and CD8+ T cells to undergo TNF-alpha-induced apoptosis, as observed by TUNEL assay and DNA fragmentation ladder assay. Increased TNF-alpha-induced apoptosis was also observed in both CD45RA+ and CD45RO+ T cells from aging subjects. An increased constitutive expression of TNFRI and TRADD and decreased expression of TNFRII and TRAF-2 were observed in lymphocytes from aged as compared with young controls. In addition, there was an early and increased activation of caspases (caspase-8 and caspase-3) involved in TNFR/TNF signaling pathway, as evident by early cleavage of caspase-8, poly(ADP-ribose) polymerase (PARP), and caspase-3 substrate DEVD-p-nitroamilide NA. These data suggest that an increased TNF-alpha-induced apoptosis may play a role in T cell deficiency associated with human aging.
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PMID:Increased TNF-alpha-induced apoptosis in lymphocytes from aged humans: changes in TNF-alpha receptor expression and activation of caspases. 997 90

Cholangiocarcinoma (CCA), a tumour of the bile duct epithelium, occurs with a higher incidence in South-east Asian countries than in Europe and North America. The prognosis is poor, due to the unavailability of early diagnosis and the tumours being relatively resistant to chemotherapy. In the present study one of the fatal routes of this tumour was studied. This death was stimulated by TNF-alpha. TNF-alpha at a concentration of 760 pg/ml and 100 pg/ml in the presence of 1 microgram/ml actinomycin D induced 50% cell death of the two established human cholangiocarcinoma cell lines HuCCA-1 and HuCCA-INu, respectively. Preincubation of both cell lines with MoAb to TNF-RI or TNF-RII before TNF-alpha treatment showed that only the MoAb specific to TNF-RI inhibited death. The death of these two cell lines was proved to be apoptosis. Western blot analysis of extracts from both cell lines demonstrated a cleavage of poly (ADP-ribose) polymerase (PARP) within 6-8 h following TNF-alpha treatment. The degradation of PARP was prevented by a MoAb to TNF-RI indicating that the TNF-RI but not TNF-RII was involved in TNF-induced apoptosis in these two human cholangiocarcinoma cell lines. Moreover, peptide inhibitor for caspase II subfamily, Ac-DEVD-CHO, reduced the cytolysis of TNF-alpha-treated cholangiocarcinoma cells. The inhibitor also prevented degradation of PARP. These results indicate that the interaction between TNF-alpha and TNF-RI alone generated a sufficient signal to activate a caspase II subfamily-dependent apoptosis in human cholangiocarcinoma cell lines.
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PMID:Binding of tumour necrosis factor-alpha (TNF-alpha) to TNF-RI induces caspase(s)-dependent apoptosis in human cholangiocarcinoma cell lines. 1020 3

Activation of poly-(ADP-ribose) polymerase (PARP) is often associated with cytotoxicity, but its precise role in shock-induced lethality and in different modes of tissue injury is still unknown. We took advantage of the existence of mice with a targeted deletion of the PARP gene (PARP-/-) to examine the differential sensitivity of wild-type (wt) and PARP-/- mice toward endotoxin (LPS)-induced lethality and different forms of liver damage. All PARP-/- animals survived high-dose (20 mg/kg) LPS-mediated shock, which killed 60% of wt animals. Moreover, LPS-induced necrotic liver damage was significantly reduced. In contrast, when apoptotic liver damage was induced via injection of low concentrations of LPS (30 microgram/kg) into D-galactosamine-sensitized mice, or via activation of hepatic cell death receptors, PARP-/- animals were not protected. We conclude that PARP is involved in systemic LPS toxicity, while it plays a minor role in apoptotic liver damage mediated by TNF or CD95.
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PMID:Prevention of endotoxin-induced lethality, but not of liver apoptosis in poly(ADP-ribose) polymerase-deficient mice. 1049 11

Apoptosis is triggered by a number of different stimuli including the activation of Fas antigen, a member of the TNF family, by the Fas ligand. The signal transduction events implicated in apoptosis are complex and remain only partially understood. In this study, we used calyculin A, a potent inhibitor of serine/threonine (ser/thr) phosphatases types 1 and 2A, to investigate the role of ser/thr phosphatases in Fas-induced apoptosis. We showed that calyculin A inhibited Fas-induced DNA fragmentation and cytolysis in Jurkat cells and that this inhibition was not due to the modulation of Fas. Okadaic acid also inhibited Fas-induced apoptosis of Jurkat cells, but at much higher concentrations (microM level), thus implicating that type 1 phosphatases rather than type 2A are inhibited at nM concentrations. Cross-linking Fas led to the dephosphorylation of the retinoblastoma gene product (Rb) within 5 min, and to PARP cleavage within 2 h. Both events were inhibited by calyculin A indicating that apoptotic death triggered by Fas cross-linking involves the activation of type 1 ser/thr phosphatases.
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PMID:Fas-mediated apoptosis in T cells involves the dephosphorylation of the retinoblastoma protein by type 1 protein phosphatases. 1062 32

In an effort to develop a safe and effective vaccine against respiratory syncytial virus (RSV), we used Escherichia coli heat-labile toxin (LT), and LTK63 (an LT mutant devoid of ADP-ribosyltransferase activity) to elicit murine CD8(+) CTL responses to an intranasally codelivered CTL peptide from the second matrix protein (M2) of RSV. M2(82-90)-specific CD8(+) T cells were detected by IFN-gamma enzyme-linked immunospot and (51)Cr release assay in local and systemic lymph nodes, and their induction was dependent on the use of a mucosal adjuvant. CTL elicited by peptide immunization afforded protection against RSV challenge, but also enhanced weight loss. CTL-mediated viral clearance was not dependent on IFN-gamma since depletion using specific mAb during RSV challenge did not affect cellular recruitment or viral clearance. Depletion of IFN-gamma did, however, reduce the concentration of TNF detected in lung homogenates of challenged mice and largely prevented the weight loss associated with CTL-mediated viral clearance. Mice primed with the attachment glycoprotein (G) develop lung eosinophilia after intranasal RSV challenge. Mucosal peptide vaccination reduced pulmonary eosinophilia in mice subsequently immunized with G and challenged with RSV. These studies emphasize that protective and immunoregulatory CD8(+) CTL responses can be mucosally elicited using enterotoxin-based mucosal adjuvants but that resistance against viral infection may be accompanied by enhanced disease.
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PMID:Mucosal delivery of a respiratory syncytial virus CTL peptide with enterotoxin-based adjuvants elicits protective, immunopathogenic, and immunoregulatory antiviral CD8+ T cell responses. 1114 91

TRAIL, Tumor necrosis factor-related apoptosis-inducing ligand), a member of the TNF family, is known to be cytotoxic for a high proportion of tumor cell lines. However, successful application of TRAIL in tumor therapy may depend on finding other agents that can potentiate its antitumor effects. The present study showed that the cytostatic/cytotoxic TRAIL activity against U937 cells could be significantly augmented by proteasome inhibitor PSI, as revealed by MTT assay. Increased cytostatic/cytotoxic effect on U937 cells by TRAIL/PSI combined treatment was caused by apoptosis, as shown by an increased PARP cleavage rate. TRAIL/PSI did not affect the level of mRNA expression for TRAIL receptors (DR4, DR5, DcR1) and other apoptosis signal transduction molecules (TRADD, caspase-8).
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PMID:Augmented pro-apoptotic effects of TRAIL and proteasome inhibitor in human promonocytic leukemic U937 cells. 1139 70

DNA fragmentation factor (DFF) comprises DFF45 and DFF40 subunits, the former of which acts as an inhibitor of the latter (the catalytic subunit) and whose cleavage by caspase-3 results in DFF activation. Disruption of the DFF45 gene blocks the generation of 50-kb DNA fragments and confers resistance to apoptosis. We recently suggested that the early fragmentation of DNA by DFF and the consequent activation of poly(ADP-ribose) polymerase-1 (PARP-1), mitochondrial dysfunction, and activation of caspase-3 contribute to an amplification loop in the apoptotic process. To verify the existence of such a loop, we have now examined the effects of restoring DFF expression in DFF45-deficient fibroblasts. Co-transfection of mouse DFF45(-/-) fibroblasts with plasmids encoding human DFF40 and DFF45 reversed the apoptosis resistance normally observed in these cells. The DFF45(-/-) cells regained the ability to fragment their DNA into 50-kb pieces in response to TNF, which resulted in a marked activation of PARP-1 and a concomitant depletion of intracellular NAD. DFF expression also resulted in an increase both in cytochrome c release into the cytosol and in caspase-3 activation triggered by TNF. These results support the importance of DFF, PARP-1, mitochondria, and caspase-3 in an amplification phase of TNF-induced apoptosis.
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PMID:Roles of DNA fragmentation factor and poly(ADP-ribose) polymerase-1 in sensitization of fibroblasts to tumor necrosis factor-induced apoptosis. 1178 71

Death ligands not only induce apoptosis but can also trigger necrosis with distinct biochemical and morphological features. We recently showed that in L929 cells CD95 ligation induces apoptosis, whereas TNF elicits necrosis. Treatment with anti-CD95 resulted in typical apoptosis characterized by caspase activation and DNA fragmentation. These events were barely induced by TNF, although TNF triggered cell death to a similar extent as CD95. Surprisingly, whereas the caspase inhibitor zVAD prevented CD95-mediated apoptosis, it potentiated TNF-induced necrosis. Cotreatment with TNF and zVAD was characterized by ATP depletion and accelerated necrosis. To investigate the mechanisms underlying TNF-induced cell death and its potentiation by zVAD, we examined the role of poly(ADP-ribose)polymerase-1 (PARP-1). TNF but not CD95 mediated PARP activation, whereas a PARP inhibitor suppressed TNF-induced necrosis and the sensitizing effect of zVAD. In addition, fibroblasts expressing a noncleavable PARP-1 mutant were more sensitive to TNF than wild-type cells. Our results indicate that TNF induces PARP activation leading to ATP depletion and subsequent necrosis. In contrast, in CD95-mediated apoptosis caspases cause PARP-1 cleavage and thereby maintain ATP levels. Because ATP is required for apoptosis, we suggest that PARP-1 cleavage functions as a molecular switch between apoptotic and necrotic modes of death receptor-induced cell death.
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PMID:Activation and caspase-mediated inhibition of PARP: a molecular switch between fibroblast necrosis and apoptosis in death receptor signaling. 1190 76


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