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 cell strain 46BR, derived from an immunodeficient individual, is hypersensitive to the lethal effects of DNA-damaging agents, and of 3-aminobenzamide (3AB), the latter being an inhibitor of the enzyme ADP-ribosyltransferase (ADPRT). This hypersensitivity is not found with the noninhibitory analogue, 3-aminobenzoate. The NAD content of 46BR cells is similar to that of fibroblasts from normal human donors, as is the decrease in NAD content following treatment with dimethylsulphate. Both the activity of ADP-ribosyltransferase and its inhibition by 3AB in permeabilized cells are similar in 46BR and in normal cell strains. High concentrations of 3AB interfere with purine metabolism in cultured cells. Again this effect is similar in 46BR and normal cells. Thus there is no apparent anomaly either in the activity of ADPRT or in the gross effects of 3AB in 46BR. The sensitivity to 3AB may be caused by a defect in a specific acceptor for the ADP-ribose synthesized by ADPRT, or in some as yet undiscovered action of the inhibitor.
Carcinogenesis 1985 Jun
PMID:NAD and the synthesis of (ADP-ribose)n in a human cell strain (46BR) hypersensitive to the lethal effects of 3-aminobenzamide. 298 9

Benzamides are potent inhibitors of nuclear ADP-ribosyltransferase and have been extensively used to demonstrate the involvement of ADP-ribosylation in cellular function. When permeabilized L1210 cells are treated with 50 microM 3-acetylamidobenzamide (3-aab) the enzyme is inhibited. However, when 50 nM 3-aab is used a two-fold stimulation of enzyme activity is produced. This anomalous stimulation is obtained with benzamides and nicotinamides and is correlated with their activity as inhibitors. Strikingly the steady-state level of poly(ADP-ribose) in intact cells is increased by these low levels of inhibitors. The mechanisms of this effect and its consequences for the experimental use of benzamides are discussed.
Carcinogenesis 1988 Nov
PMID:Benzamides can stimulate as well as inhibit the activity of nuclear ADP-ribosyltransferase. 314 Oct 76

Following treatment of human fibroblasts with dimethyl-sulphate, more breaks persisted in DNA in cells incubated with 3-aminobenzamide, an inhibitor of ADP-ribosyltransferase, than in its absence. This effect of 3-aminobenzamide was more pronounced in non-dividing than in dividing cells. If non-dividing cells were treated with dimethylsulphate and then incubated for a few hours in the absence of 3-aminobenzamide, few breaks were detectable in the DNA. Subsequent addition of 3-aminobenzamide resulted in the reappearance of many breaks in the DNA. These data suggest that continued synthesis of poly(ADP-ribose) reduces the steady state level of breaks during excision repair of alkylation damage. This is probably mediated by the stimulation of DNA ligase activity. Inhibition of poly(ADP-ribose) synthesis with 3-aminobenzamide maintains or restores a higher steady-state level of breaks.
Carcinogenesis 1984 Jan
PMID:Poly(ADP-ribosylation) reduces the steady-state level of breaks in DNA following treatment of human cells with alkylating agents. 631 22

There is compelling evidence for the central role of oxidative damage in the aging process and for the participation of reactive oxygen species in tumor initiation and promotion. Caloric restriction (CR) or energy restriction retards age-associated increases in mitochondrial free-radical production and reduces the accumulation of oxidatively damaged cell components. CR has also been shown to slow down age-related declines in various repair capabilities, including some types of DNA repair. It is proposed that inhibitors of mitochondrial electron transport and/or uncouplers of oxidative phosphorylation (rotenone, amytal, amiodarone, valinomycin, etc.), when used at extremely low doses, could mimic the effects of CR in model systems. The objective is to lower mitochondrial free-radical production by decreasing the fraction of electron carriers in the reduced state. In addition to a variety of other effects, CR has been shown to increase the rate of apoptosis, particularly in preneoplastic cells, and in general, to promote elevated levels of free glucocorticoids (GCs). GCs are known to induce tissue-specific apoptosis and to upregulate gap-junction-mediated intercellular communication (GJIC). Tumor promoters like phorbol esters have the opposite effect, in that they inhibit both the process of apoptosis and GJIC. The enzyme poly (ADP-ribose) polymerase (PARP) is thought to play a central role in apoptosis, in a manner that has been highly conserved in evolution. There is good evidence that the apoptosis-associated Ca/Mg-dependent DNA endonuclease is maintained in a latent form by being poly (ADP-ribosylated). Apoptosis would require the removal of this polymer from the endonuclease, and, most likely, its removal from topoisomerase II and histone H1 as well. The role of poly (ADP-ribose) in apoptosis, carcinogenesis, and aging could be studied by the use of modulators of PARP activity (3-aminobenzamide, 3-nitrosobenzamide, 1% ethanol, etc.), inhibitors of poly ADP-ribose) glycohydrolase activity (ethacridine, 43 degrees C, etc.), and inhibitors of the PARP-specific protease (interleukin-1 beta converting enzyme (ICE)-like protease). Also, it would be of interest to determine if CR can decrease the half-life of poly (ADP-ribose), upregulate GJIC, and modulate the activities of PARP, the glycohydrolase, and the PARP-specific protease, factors potentially important in these processes.
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PMID:The beneficial effects of dietary restriction: reduced oxidative damage and enhanced apoptosis. 865 88

Weanling male F344 rats were fed either a semi-purified diet low in methionine and lacking in choline and folic acid (folate/methyl deficient) or a supplemented control diet for periods of 2, 5, 7 days, 3 weeks, and 9 weeks. Two days after initiating the folate/methyl deficient diet in weanling F344 rats, the incidence of apoptotic bodies, identified by in situ end-labeling of 3'-OH DNA strand breaks, was significantly increased in liver sections from the deficient rats. Apoptotic cell death was confirmed biochemically by an increase in nuclear Ca2+/Mg2+-dependent endonuclease activity that paralleled the increase in apoptotic bodies over the 9-week feeding period. There was no morphologic evidence of necrotic foci or necrosis-associated inflammatory response over the 9-week period. Confirming that cell turnover is chronically elevated in this model, the increase in apoptotic rate was accompanied by a sustained increase in the mitotic index (MI). The DNA repair-associated enzyme, poly(ADPribose) polymerase (PARP), was similarly elevated and was associated with significant decreases in the substrate for ADPribose polymer synthesis, nicotinamide adenine dinucleotide (NAD). Because folate metabolites are essential for de novo purine and thymidine biosynthesis, prolonged deficiency in folic acid can induce an imbalance in the deoxynucleotide precursors for DNA replication/repair and negatively affect the fidelity of DNA synthesis. Using an HPLC method, hepatic deoxyuridine triphosphate (dUTP) levels were increased at 3 and 9 weeks after initiation of the deficient diet and levels of thymidine triphosphate (dTTP) were reduced. An increase in dUTP/ dTTP ratio is consistent with a block in folate-dependent de novo thymidylate biosynthesis and may predispose to uracil misincorporation and DNA repair-related DNA strand breaks.
Carcinogenesis 1997 Feb
PMID:Apoptosis and proliferation under conditions of deoxynucleotide pool imbalance in liver of folate/methyl deficient rats. 905 20

Poly(ADP-ribose) polymerase (PARP, EC 2.4.2.30) is a nuclear enzyme possibly involved in DNA base excision repair. The presence of single- or double-strand breaks in DNA stimulates this enzyme to covalently modify acceptor proteins with poly(ADP-ribose) in a reaction that uses NAD+ as substrate. To test the hypothesis that increased PARP activity could promote resistance towards DNA-damaging agents and gamma-radiation, we established stable rat cell transfectants that constitutively express human PARP. A number of subclones that showed different levels of PARP activity were isolated from two primary transfectants of different clonal origin. PARP activity was determined in permeabilized cells after maximal stimulation with a short, double-stranded oligonucleotide. Activity in different human PARP-expressing subclones was increased 1.6- to 3.1-fold compared with non-expressing subclones. In vivo labeling of poly(ADP-ribose) was performed in one of these subclones, revealing that the level of poly(ADP-ribose) accumulation after the same treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was four times higher in the human PARP-expressing subclone compared with both non-expressing transfected control cells and parental cells. Clonal survival assays revealed a sensitization upon treatment with gamma-radiation (up to 1.4-fold) or MNNG (up to 2.7-fold) of several subclones expressing human PARP; in some others survival was not changed. Survival after cisplatin (DDP) treatment remained essentially unchanged. A protective effect against DNA-damage was never observed. We conclude that human PARP overexpression in rodent cells leads to increased poly(ADP-ribosyl)ation capacity and does not promote survival after gamma-radiation or treatment with the DNA-damaging agents MNNG or DDP.
Carcinogenesis 1997 Apr
PMID:Functional overexpression of human poly(ADP-ribose) polymerase in transfected rat tumor cells. 911 Nov 97

The effects of 2-butoxyethanol (2-BE) on poly(ADP-ribosyl)ation were studied in Syrian hamster embryo (SHE) cells by measuring the cellular concentrations of the polymer poly(ADP-ribose) (pADPr) and of NAD+, the substrate of poly(ADP-ribose) polymerase (PARP). As biotransformation pathways of ethylene glycol ethers involve NAD+-dehydrogenases, it was hypothesized that 2-BE could reduce poly(ADP-ribosyl)ation by consuming NAD+. As a result DNA repair could be altered, which would explain that 2-BE had been shown to potentiate the effects of clastogenic substances such as methyl-methanesulfonate (MMS). In this study, the effects of 2-BE on MMS-induced pADPr metabolism were analyzed. The results indicated that: (i) 2-BE (5 mM) by itself did not influence significantly pADPr or NAD+ levels. (ii) 2-BE inhibited pADPr synthesis in MMS (0.2 mM)-pretreated cells, without any change in NAD+ concentrations. (iii) MMS treatment, which rapidly increased pADPr levels, also affected the poly(ADP-ribosyl)ation system as a secondary effect by damaging cell structures. Membrane permeabilization, which occurred at concentrations >1 mM MMS, led to a dramatic leakage of cellular NAD+ resulting in a strong reduction in pADPr levels. (iv) A bleomycin pulse (100 microM) applied after MMS and/or 2-BE treatment confirmed that 2-BE reduced poly(ADP-ribosyl)ation capacities of MMS-treated cells, though the glycol ether had no effect alone. This study confirmed that the inhibition of pADPr synthesis could be responsible for the synergistic effects of 2-BE with genotoxic substances. The mechanism of this inhibition cannot be explained by a lack of NAD+ at the concentrations of 2-BE tested.
Carcinogenesis 1997 Dec
PMID:Alteration in methyl-methanesulfonate-induced poly(ADP-ribosyl)ation by 2-butoxyethanol in Syrian hamster embryo cells. 945 Apr 78

Resveratrol, a constituent of grapes and other food products, has been shown to prevent carcinogenesis in murine models. We report here that resveratrol induces apoptotic cell death in HL60 human leukemia cell line. Resveratrol-treated tumor cells exhibit a dose-dependent increase in externalization of inner membrane phosphatidylserine and in cellular content of subdiploid DNA, indicating loss of membrane phospholipid asymmetry and DNA fragmentation. Resveratrol-induced cell death is mediated by intracellular caspases as observed by the dose-dependent increase in proteolytic cleavage of caspase substrate poly (ADP-ribose) polymerase (PARP) and the ability of caspase inhibitors to block resveratrol cytotoxicity. We also show that resveratrol treatment enhances CD95L expression on HL60 cells, as well as T47D breast carcinoma cells, and that resveratrol-mediated cell death is specifically CD95-signaling dependent. On the contrary, resveratrol treatment of normal human peripheral blood lymphocytes (PBLs) does not affect cell survival for up to 72 hours, which correlates with the absence of a significant change in either CD95 or CD95L expression on treated PBLs. These data show specific involvement of the CD95-CD95L system in the anti-cancer activity of resveratrol and highlight the chemotherapeutic potential of this natural product, in addition to its recently reported chemopreventive activity.
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PMID:Chemopreventive agent resveratrol, a natural product derived from grapes, triggers CD95 signaling-dependent apoptosis in human tumor cells. 968 Mar 69

Poly(ADP-ribose) polymerase (PARP) is a constitutive factor of the DNA damage surveillance network in dividing cells. Based on its capacity to bind to DNA strand breaks, PARP plays a regulatory role in their resolution in vivo. ATM belongs to a large family of proteins involved in cell cycle progression and checkpoints in response to DNA damage. Both proteins may act as sensors of DNA damage to induce multiple signalling pathways leading to activation of cell cycle checkpoints and DNA repair. To determine a possible relationship between PARP and ATM, we examined the PARP response in an ATM-null background. We demonstrated that ATM deficiency does not affect PARP activity in human cell lines or Atm-deficient mouse tissues, nor does it alter PARP activity induced by oxidative damage or gamma-irradiation. Our results support a model in which PARP and ATM could be involved in distinct pathways, both effectors transducing the damage signal to cell cycle regulators.
Carcinogenesis 1999 Jan
PMID:Poly(ADP-ribose) polymerase activity is not affected in ataxia telangiectasia cells and knockout mice. 993 67

DNA-dependent protein kinase (DNA-PK) and poly(ADP-ribose) polymerase (PARP) are activated by DNA strand breaks and participate in DNA repair. We investigated the interactive effects of inhibitors of these enzymes [wortmannin (WM), which inhibits DNA-PK, and 8-hydroxy-2-methylquinazolin-4-one (NU1025), a PARP inhibitor] on cell survival and DNA double-strand break (DSB) and single-strand break (SSB) rejoining in Chinese hamster ovary-K1 cells following exposure to ionizing radiation (IR) or temozolomide. WM (20 microM) or NU1025 (300 microM) potentiated the cytotoxicity of IR with dose enhancement factors at 10% survival (DEF10) values of 4.5 +/- 0.6 and 1.7 +/- 0.2, respectively. When used in combination, a DEF10 of 7.8 +/- 1.5 was obtained. WM or NU1025 potentiated the cytotoxicity of temozolomide, and an additive effect on the DEF10 value was obtained with the combined inhibitors. Using the same inhibitor concentrations, their single and combined effects on DSB and SSB levels following IR were assessed by neutral and alkaline elution. Cells exposed to IR were post-incubated for 30 min to allow repair to occur. WM or NU1025 increased net DSB levels relative to IR alone (DSB levels of 1.29 +/- 0.04 and 1.20 +/- 0.05, respectively, compared with 1.01 +/- 0.03 for IR alone) and the combination had an additive effect. WM had no effect on SSB levels, either alone or in combination with NU1025. SSB levels were increased to 1.27 +/- 0.05 with NU1025 compared with IR alone, 1.02 +/- 0.04. The dose-dependent effects of the inhibitors on DSB levels showed that they were near maximal by 20 microM WM and 300 microM NU1025. DSB repair kinetics were studied. Both inhibitors increased net DSB levels over a 3 h time period; when they were combined, net DSB levels at 3 h were identical to DSB levels immediately post-IR. The combined use of DNA repair inhibitors may have therapeutic potential.
Carcinogenesis 1999 Feb
PMID:Interactive effects of inhibitors of poly(ADP-ribose) polymerase and DNA-dependent protein kinase on cellular responses to DNA damage. 1006 54


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