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)

Under pathological conditions, the mode of cell death, apoptosis or necrosis, is relevant for the subsequent fate of the tissue. Cell demise may be shaped by endogenous mediators such as nitric oxide (NO) which interfere with subroutines of the death program. Here we show that apoptosis of Jurkat cells elicited by either staurosporine (STS) or anti-CD95 antibodies in glucose-free medium is converted to necrosis by NO donors. In the presence of NO, release of mitochondrial cytochrome c was delayed and activation of execution caspases was prevented. Stimulated cells died nonetheless. The switch in the mode of cell death was due to NO-dependent failure of mitochondrial energy production. Restoration of intracellular ATP by glucose supplementation recovered the cells' ability to activate caspases and undergo apoptosis. In this system, the apoptosis/necrosis conversion promoted by NO was not mediated by cyclic guanosine monophosphate-dependent mechanisms, poly-(ADP-ribose)-polymerase (PARP) activation, or inhibition of caspases due to S-nitrosylation and glutathione depletion. In contrast, depleting intracellular ATP with rotenone, an inhibitor of mitochondrial complex I mimicked the effect of NO. The findings presented here suggest that NO can decide the shape of cell death by lowering intracellular ATP below the level required to allow the coordinated execution of apoptosis.
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PMID:Inhibition of mitochondrial ATP generation by nitric oxide switches apoptosis to necrosis. 1036 39

Although nitric oxide (NO) induces neuronal cell death under some conditions, it also can prevent apoptosis resulting from growth factor withdrawal. We investigated the molecular mechanism by which NO protects undifferentiated and differentiated PC12 cells from trophic factor deprivation-induced apoptosis. PC12 cells underwent apoptotic death in association with increased caspase-3-like activity, DNA fragmentation, poly(ADP-ribose) polymerase (PARP) cleavage, and cytochrome c release after 24 hr of serum withdrawal. The apoptosis of PC12 cells was inhibited by the addition of NO-generating donor S-nitroso-N-acetylpenicillamine (SNAP) (5-100 microM) and the specific caspase-3-like protease inhibitor Ac-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-cho) but not the YVADase (or caspase-1-like protease) inhibitor N-acetyl-Tyr-Val-Ala-Asp-aldehyde (Ac-YVAD-cho). SNAP and Ac-DEVD-cho prevented the increase in DEVDase (caspase-3-like protease) activity. The SNAP-mediated suppression of DEVDase activity was only minimally reversed by the incubation of cell lysate with dithiothreitol, indicating that NO did not S-nitrosylate caspase-3-like proteases in PC12 cells. Western blot analysis showed that NO inhibited the proteolytic activation of caspase-3. The cGMP analog 8-bromo-cGMP (8-Br-cGMP) blocked apoptotic cell death, caspase-3 activity and activation, and cytochrome c release. The soluble guanylyl cyclase inhibitor 1-H-oxodiazol-[1,2,4]-[4,3-a] quinoxaline-1-one (CODQ) significantly attenuated NO-mediated, but not 8-Br-cGMP-dependent, inhibition of apoptotic cell death, PARP cleavage, cytochrome c release, and DEVDase activity. Furthermore, the protein kinase G inhibitor KT5823 reversed both SNAP- and 8-Br-cGMP-mediated anti-apoptotic events. All these apoptotic phenomena were also suppressed by NO production through neuronal NO synthase gene transfer into PC12 cells. Furthermore, similar findings were observed in differentiated PC12 cells stimulated to undergo apoptosis by NO donors and NGF deprivation. These findings indicate that NO protects against PC12 cell death by inhibiting the activation of caspase proteases through cGMP production and activation of protein kinase G.
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PMID:Nitric oxide protects PC12 cells from serum deprivation-induced apoptosis by cGMP-dependent inhibition of caspase signaling. 1043 31

Human fibroblasts and keratinocytes possess nitric oxide synthases (NOS), which metabolize L-arginine (L-Arg) for producing nitric oxide (NO*). This report delineates the relations between NO* and UVA in the human keratinocyte cell line HaCaT. NOS activity was stimulated by exposure of cells to L-Arg just after irradiation. L-Arg (5 mM) supply led to an increase in UVA (25.3 J/cm(2)) cytotoxicity (% of viability 18 +/- 3%) whereas neither L-Arg itself nor UVA irradiation induced cell death at the doses used in this study. Cells were also treated either with L-thiocitrulline (L-Thio), an irreversible inhibitor of NOS, or with exogenous superoxide dismutase (SOD) and catalase. L-Thio and SOD prevented L-Arg-mediated deleterious effects in irradiated cells, whereas catalase was ineffective. Intracellular antioxidant enzyme activities were also determined. UVA/L-Arg stress altered catalase (66% decrease) and glutathione peroxidase (83% decrease). DNA damage was evaluated using the 'comet assay' and quantified using the 'tail moment'. UVA alone was genotoxic (mean tail moment: 25.43 +/- 1.23, P<0.001 compared control cells). The addition of L-Arg potentiated DNA damage (mean tail moment: 41.05+/-3.9) whereas L-Thio prevented them (mean tail moment 9.86 +/- 0.98). We attempted to assess the effect of poly(ADP-ribose) polymerase (PARP) inhibition on cell death. Using the PARP inhibitor 3-aminobenzamide, we established that PARP determines both cell lysis and DNA damage induced by UVA and/or L-Arg. Our findings demonstrated that L-Arg was able to increase UVA-mediated deleterious effects in keratinocytes (both DNA damage and cytotoxicity) and that the ratio NO*/O2*- plays a key role in these processes.
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PMID:L-arginine increases UVA cytotoxicity in irradiated human keratinocyte cell line: potential role of nitric oxide. 1050 85

It has been recognized that natural killer (NK) cells destroy AK-5 tumor cells, largely by cytolysis and apoptosis. The objective of this study was to elucidate the existence and the role of nitric oxide (NO) during this killing. The target cell killing ability of NK cells was associated with an increased production of NO with higher expression of inducible nitric oxide synthase. In part, the production of NO was confirmed by significant increase in cell lysis in the presence of l-arginine and attenuation of cell lysis, DNA fragmentation, and apoptosis by N(omega)-nitro-l-arginine methyl ester (L-NAME). An increased oxidation of intracellularly trapped dichlorofluorescein was observed in NK cells, which was effectively prevented by L-NAME. Exposure of AK-5 cells to chemically generated NO also induced DNA fragmentation in AK-5 cells. Further evidence for the involvement of NO in apoptosis was provided by the inhibition of specific cleavage of PARP and activation of CPP32 by L-NAME. Increased production of NO with simultaneous enhancement of the cytotoxic activity of NK cells from sc tumor-transplanted animals has been implicated in tumor regression when compared to the ip tumor-bearing animals. Overall, these observations suggest an important role for NO during NK cell-mediated apoptosis and lysis of AK-5 cells.
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PMID:Induction of nitric oxide production by natural killer cells: its role in tumor cell death. 1053 45

In this study, both NIH3T3 and Bcl-2 transfected NIH3T3 cells were examined for their propensity to undergo nitroso compound-induced apoptosis. Bcl-2-expressing NIH3T3 prevented N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)- and S-nitrosoglutathione (GSNO)-induced apoptosis as compared with the control NIH3T3 cells. Flow cytometry revealed that NIH3T3 cells treated with MNNG undergo apoptotic death, which occurred after G2-M arrest in the second cycle of cell proliferation. The mechanism of MNNG-induced NIH3T3 cells apoptosis was observed throughout the activation of caspase-3 protease, PARP degradation and cytochrome c release; it was independent of p53 activation. Glutathione-S-transferanse pi (GST pi) is activated through the transcription activation of antioxidant response element (ARE) during MNNG- and GSNO-induced cell apoptosis. Moreover, overexpression of Bcl-2 in NIH3T3 cells can prevent these features of cell death. Furthermore, both MNNG- and GSNO-induced apoptosis of NIH3T3 cells were accompanied with a decrease in the level of glutathione (GSH); whereas Bcl-2 overexpression led to an increase in total cellular glutathione. MNNG was metabolized rapidly to nitric oxide that reacted with glutathione under the catalysis of GSH transferase in NIH3T3 cell to form GSNO. In short, the production of GSNO in cells was found capable of apoptosis initiation while the overexpression of Bcl-2 can prevent MNNG-mediated cell apoptosis through the elevation of glutathione levels.
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PMID:Suppression of N-methyl-N'-nitro-N-nitrosoguanidine- and S-nitrosoglutathione-induced apoptosis by Bcl-2 through inhibiting glutathione-S-transferase pi in NIH3T3 cells. 1059 28

Nitric oxide (NO) and its reactant product, peroxynitrite, have been implied to mediate neuronal damage following cerebral ischemia. However, the cellular targets of these compounds remain unclear. Studies using poly(ADP-ribose) polymerase (PARP) inhibitors and PARP knock-out mice have recently demonstrated that excessive activation of this nuclear enzyme plays an important role in NO-induced neurotoxicity. To evaluate the relevance of this plausible candidate gene to human stroke, we undertook a case-control study in Japanese. Participants comprised 213 cerebral infarction cases and 374 age- and sex-matched controls. As a primary investigation, we screened polymorphic sites of the PARP gene, and newly identified a total of four polymorphisms in 1230-bp 5'-flanking sequence. None of them were, however, located on the known promoter components of the gene. Two bi-allelic polymorphisms selected and a CA-repeat polymorphism were subsequently characterized in the case-control study, but none were significantly associated with cerebral infarction in the present study. Our data thus suggest that the tested PARP polymorphisms do not principally contribute to cerebral infarction, although extensive searches would be required to clarify whether the PARP gene plays an important role in the pathogenesis of human stroke.
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PMID:Evaluation of the poly(ADP-ribose) polymerase gene in human stroke. 1065 71

Activation of the nuclear enzyme poly(ADP-ribose)polymerase (PARP) is a critical step in beta-cell death in response to exposure with free radicals or other DNA damaging agents. Nicotinamide, a B vitamin, exerts its beta-cell protective action primarily via its ability to block excessive PARP activity. We show here that the isoquinolinone derivative PD128763, a specific PARP inhibitor, provides protection from cell death in islet cells exposed in vitro to nitric oxide or oxygen radical generating compounds or to the beta-cell toxin streptozotocin, at concentrations 100 times less than required for nicotinamide. Furthermore, while the protective action of nicotinamide is rapidly lost after washing of islet cells, the effects of PD128763 are more long lasting. Both compounds had little capacity to rescue damaged islet cells from subsequent lysis. We conclude that the isoquinolinone derivative PD128763 is superior to nicotinamide in enhancing the resistance of beta-cells towards inflammatory attacks.
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PMID:Potent beta-cell protection in vitro by an isoquinolinone-derived PARP inhibitor. 1066 15

Extracellular recording techniques were used to study the effects of the nitric oxide releasing agents diethylamine-NO (DEA-NO) and S-nitroso-N-acetyl-penicillamine (SNAP) on synaptic transmission in the intermediate and medial part of the hyperstriatum ventrale (IMHV), a part of the domestic chick forebrain that is essential for some forms of early learning. The field response evoked by local electrical stimulation was recorded in the IMHV in an in vitro slice preparation. DEA-NO (100-200 mgr) significantly depressed the field response in a concentration dependent and reversible manner. However, the depression produced by perfusion with 400 mgr DEA-NO, was not reversed following washout of the drug. With 400 mgr DEA-NO, NO reaches a maximum concentration of 10 mgr at 2 min of perfusion, and then declines slowly. SNAP (400 mgr) produced an effect similar to 400 mgr DEA-NO. Neither the immediate nor the longer-term depressive effect of NO is mediated by activation of guanylyl cyclase because in the presence of both low and high doses of ODQ, a potent and selective inhibitor of NO-stimulated guanylyl cyclase, NO produced the same depression of the field response. There is evidence however that the IMHV possesses c-GMP responsive elements since direct perfusion of 8-Br-cGMP (1 mM) produced a long-term but not an immediate depression. The long-term depression produced by 400 mgr DEA-NO was eliminated in the presence of either a selective adenosine A(1) receptor antagonist or an ADP-ribosyltransferase inhibitor. It was also possible to prevent the long-term effect in the presence of tetraethyl ammonium a K(+)-channel blocker. These results suggest that the NO may be acting presynaptically in a synergistic fashion with the adenosine A(1) receptor to depress transmitter release.
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PMID:Effects of nitric oxide release in an area of the chick forebrain which is essential for early learning. 1083 95

Poly(ADP-ribose) polymerase (PARP-1), a nuclear enzyme that facilitates DNA repair, may be instrumental in acute neuronal cell death in a variety of insults including, cerebral ischemia, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonism, and CNS trauma. Excitotoxicity is thought to underlie these and other toxic models of neuronal death. Different glutamate agonists may trigger different downstream pathways toward neurotoxicity. We examine the role of PARP-1 in NMDA- and non-NMDA-mediated excitotoxicity. NMDA and non-NMDA agonists were stereotactically delivered into the striatum of mice lacking PARP-1 and control mice in acute (48 hr) and chronic (3 week) toxicity paradigms. Mice lacking PARP-1 are highly resistant to the excitoxicity induced by NMDA but are as equally susceptible to AMPA excitotoxicity as wild-type mice. Restoring PARP-1 protein in mice lacking PARP-1 by viral transfection restored susceptibility to NMDA, supporting the requirement of PARP-1 in NMDA neurotoxicity. Furthermore, Western blot analyses demonstrate that PARP-1 is activated after NMDA delivery but not after AMPA administration. Consistent with the theory that nitric oxide (NO) and peroxynitrite are prominent in NMDA-induced neurotoxicity, PARP-1 was not activated in mice lacking the gene for neuronal NO synthase after NMDA administration. These results suggest a selective role of PARP-1 in glutamate excitoxicity, and strategies of inhibiting PARP-1 in NMDA-mediated neurotoxicity may offer substantial acute and chronic neuroprotection.
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PMID:NMDA but not non-NMDA excitotoxicity is mediated by Poly(ADP-ribose) polymerase. 1105 Jan 21

In mammals, visual experience during early postnatal life is critical for normal development of the visual system. Here we report that monocular deprivation for 2, 7, and 14 consecutive days causes p53 accumulation, cell death, and progressive loss of neurones in the dorsal lateral geniculate nucleus (dLGN) of newborn rats and these are prevented by NMDA and non-NMDA glutamate receptor antagonists, and by L-NAME, an inhibitor of nitric oxide synthesis. Monocular deprivation also increases dLGN levels of citrulline, the coproduct of nitric oxide synthesis, and this, as well as cell death and neuronal loss, is abolished by antagonists of glutamate receptors and by L-NAME. Finally, poly-(ADP-ribose) polymerase (PARP) knock-out mice appear to be protected from monocular deprivation-induced cell death. In conclusion, during early postnatal development of the rat visual system monocular deprivation causes excitotoxic, nitric oxide-mediated, cell death in the dLGN that appears to be apoptotic and also requires activation of PARP.
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PMID:Apoptosis in the dorsal lateral geniculate nucleus after monocular deprivation involves glutamate signaling, NO production, and PARP activation. 1109 43


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