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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epstein-Barr virus (EBV) has been found to be associated with nasopharyngeal carcinoma (NPC), and antibodies with high frequency and titer to EBV proteins have been found in sera from NPC patients. Raji cells, an EBV genome-carrying nonproducer cell line, treated with 12-O-tetradecanoylphorbol-13-acetate and n-butyrate induced a unique EBV DNA polymerase which has properties similar to the EBV DNA polymerase induced by 12-O-tetradecanoylphorbol-13-acetate in P3HR-1 cells, an EBV producer cell line. The possible presence of antibodies to this EBV DNA polymerase in NPC patient serum was examined. The mean number of EBV DNA polymerase units neutralized was 380 +/- 168 units/ml serum (mean +/- SD) in 48 sera from patients with NPC, whereas that in the sera from 52 healthy donors was 62 +/- 56 units/ml (p less than 0.01). The EBV DNA polymerase antibody was found to be associated with the immunoglobulin G but not the immunoglobulin A fraction, and its titer was not correlated with the titers against EBV DNase or virus capsid antigen-immunoglobulin A. Whether the EBV DNA polymerase antibody is against the EBV DNA polymerase core protein or its stimulating protein is still being investigated. This study demonstrated the high frequency and high titer of antibody against EBV DNA polymerase in serum from NPC patients and suggested the potential of utilizing this antibody titer to complement other methods for the early diagnosis or prognosis of NPC.
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PMID:Demonstration of Epstein-Barr virus-specific DNA polymerase in chemically induced Raji cells and its antibody in serum from patients with nasopharyngeal carcinoma. 301 19

The effect of mercuric acetate on the activities of deoxyuridine triphosphate nucleotidohydrolase (dUTPase), DNA polymerase (alpha, beta), and uracil-DNA glycosylase has been studied in cultured human KB cells. There was a dose- and time-dependent inactivation of both dUTPase and DNA polymerase alpha activities by mercuric acetate. In cells exposed to low concentrations (10 microM) of mercuric acetate, dUTPase was most sensitive to inhibition with 30% of the activity being inhibited after a 1-hr exposure. At higher concentrations or for longer exposure times, DNA polymerase alpha was most sensitive to inhibition with greater than 60% of the activity being inhibited by 25 microM mercuric acetate after a 15-min exposure. There was no inhibition of DNA polymerase beta or uracil-DNA glycosylase activities in cells exposed to 50 microM mercuric acetate for 90 min. In fact, there was a time- and dose-dependent activation of uracil-DNA glycosylase activity with maximum activation occurring in cells exposed to 50 microM mercuric acetate. The inhibition of dUTPase and DNA polymerase alpha activities and the activation of uracil-DNA glycosylase activity correlated with the induction of single-strand breaks in DNA by mercuric acetate and with the decrease in cell viability.
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PMID:In vivo effects of mercury (II) on deoxyuridine triphosphate nucleotidohydrolase, DNA polymerase (alpha, beta), and uracil-DNA glycosylase activities in cultured human cells: relationship to DNA damage, DNA repair, and cytotoxicity. 302 30

The aggregation factor (AF) of the marine sponge Geodia cydonium recognizes the aggregation receptor (AR) which is inserted in the plasma membrane, under formation of species-specific aggregates. The specific cell-binding fragment of the AF was used to investigate for the first time the phosphoinositide metabolism in a lower avertebrate system. We found that after binding of the cell-binding fragment to the aggregation receptor a strong and rapid stimulation of the phosphate incorporation into phosphatidylinositol occurs followed by an increased turnover of phosphoinositides in the Geodia cells. The consequences of an increased degradation of phosphatidylinositol 4,5-bisphosphate into the two second messengers inositol-1,4,5-trisphosphate and diacylglycerol are 2-fold. First, after the addition of the extracellular stimulus the cytosolic Ca2+ concentration rises, resulting in a rapid increased Ca2+ efflux rate. The functional consequence of the increase of the extracellular Ca2+ level is an initiation of the aggregate formation that is mediated by the collagen assembly factor (= primary aggregation factor). Second, some experimental evidences are presented, showing that the other second messenger formed, diacylglycerol, causes a translocation of protein kinase C within the cell. Incubation of Geodia cells with the cell-binding fragment of the AF, or with the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, resulted within 5 min after treatment in a 70% decrease in protein kinase C activity in the cytosolic fraction and in a 700% increase in enzyme activity in the membrane fraction. It is proposed that by membrane association protein kinase C becomes activated. As a result of this event a series of cellular proteins are phosphorylated, a process which ultimately leads to an unusually strong induction of DNA polymerase alpha activity. From these data we conclude that inositol trisphosphate and protein kinase C also play a fundamental role in cellular signal transduction in lower eukaryotes.
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PMID:Role of the aggregation factor in the regulation of phosphoinositide metabolism in sponges. Possible consequences on calcium efflux and on mitogenesis. 303 73

Phorbol esters and n-butyrate (SB) together could induce Epstein-Barr virus (EBV) DNA polymerase and DNase activities in Raji cells (virus nonproducer). Neither 12-O-tetradecanoylphorbol-13-acetate (TPA) nor SB alone could induce these EBV enzyme activities, transcription of the EcoRI C-region or other EBV proteins in Raji cells. The enzyme induction caused by exposure of Raji cells to TPA-SB was the result of the synthesis of virus-specified RNA, and the increase of linear EBV DNA content in Raji cells caused by TPA alone was not sufficient for induction of EBV-enzyme activities. Temporal characteristics of the TPA-SB induction process, but not the phorbol 12,13-dibutyrate-SB induction process, in Raji cells were observed; a critical phase (10-24 h) postphorbol ester treatment in phorbol 12,13-dibutyrate-SB-treated Raji cells which was responsible for the synthesis of virus RNA and enzymes was found. Phospholipase C, which increases intracellular diacylglycerols (and subsequently activates protein kinase C) was able to partially substitute for TPA in the TPA-SB induction for EBV polymerase and DNase activities. Sphingosine, a protein kinase C inhibitor, partially prevented the induction of virus enzyme activities in Raji cells treated with phorbol 12,13-dibutyrate and SB. No apparent changes in the methylation state of EBV DNA (EcoRI C region) were observed when Raji cells were treated with SB and TPA, alone or in combination. These results suggest that induction of EBV polymerase and DNase activities by TPA-SB may involve protein kinase C activation and another factor triggered by SB which together increase transcription of EBV DNA.
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PMID:Induction of virus enzymes by phorbol esters and n-butyrate in Epstein-Barr virus genome-carrying Raji cells. 303 11

The effects of lead acetate on DNA and RNA synthesis have been investigated with intact HeLa cells, isolated nuclei, and purified DNA and RNA polymerases. No inhibition of DNA or RNA synthesis in intact cells was found even after exposure to 0.5 mM lead acetate for 18 hr. In contrast, both DNA and RNA synthesis in isolated nuclei were inhibited by lead (with 50% inhibition at approximately 150 and 80 microM respectively). Similarly, both HeLa DNA polymerase alpha and RNA polymerase II were inhibited, with 50% inhibition obtained at approximately 150 and 20 microM lead acetate respectively. The inhibition of nucleic acid synthesis in isolated nuclei can thus be accounted for by inhibition of the polymerases. The sensitivity of Escherichia coli DNA polymerase I to lead acetate was found to be significantly greater than the HeLa DNA polymerase alpha (50% inhibition at only 10 microM), but the sensitivity of the E. coli RNA polymerase was the same as that of the HeLa enzyme.
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PMID:Effects of lead acetate on DNA and RNA synthesis by intact HeLa cells, isolated nuclei and purified polymerases. 381 70

Treatment of lymphoid 594S/F9 cells with 12-o-tetradecanoylphorbol-13-acetate (TPA), cycloheximide (CH) has no effect on cell proliferation. A reversible blocking of the cellular DNA and RNA synthesis is observed. Repeated treatment with TPA, iododeoxyuridine (IDU) or sodium butyrate (SB) causes more pronounced changes in cell metabolism, which sharply decreases the salt sensitive DNA polymerase activity. Simultaneously the activity of the virus-induced ammonium sulphate resistant DNA polymerase increases. The combined effect of TPA and CH stimulates the synthesis of viral antigens in certain latently infected cells. The number of productively infected cells remains approximately at the same level for 96 h. IDU has a highest effect on viral antigens expression at repeated induction.
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PMID:[Induction of baboon herpes virus antigens in producing lymphoblastoid cells]. 621 Jan 92

The diterpene ester promoter of mouse skin tumors, 12-O-tetradecanoylphorbol-13-acetate (TPA), efficiently induces Epstein-Barr virus (EBV)-associated DNA polymerase (DNA nucleotidyltransferase) activity in the EBV-producing lymphoblastoid cell line, P3HR-1. With the use of intervent dilution chromatography followed by sequential DEAE-cellulose and phosphocellulose column chromatography, the virus-associated enzyme has been isolated and purified 300-fold. The partially purified EBV DNA polymerase activity could be distinguished from cellular polymerases by its activation with salt and its degree of sensitivity to N-ethylmaleimide and phosphonoacetic acid. The enzyme showed maximum activity for copying activated calf thymus DNA in the presence of 100 mM ammonium sulfate. In the absence of salt, the enzyme utilized with high efficiency deoxyoligomer-homopolymer templates, but failed to copy poly(rA) . oligo(dT)10 and oligo(dT)10, showing that the enzyme had properties distinct from DNA polymerase gamma, reverse transcriptase, and terminal deoxynucleotidyltransferase. The partially purified enzyme is strongly inhibited by acyclovir triphosphate and thus has properties similar to herpes simplex virus DNA polymerase.
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PMID:Induction of Epstein-Barr virus-associated DNA polymerase by 12-O-tetradecanoylphorbol-13-acetate. Purification and characterization. 624 99

Replication of simian virus 40 (SV40) chromatin in vitro is inhibited by chloride but stimulated by acetate anions even at physiological concentrations of 100-200 mM. In a similar fashion DNA polymerase alpha is affected with respect to the activity with activated DNA as primer template. Furthermore, at concentrations of 100-200 mM acetate DNA polymerase alpha remains associated with replicating chromatin, whereas association is strongly reduced when chloride anions are used at the corresponding concentrations. Thus the salt behaviour of DNA polymerase alpha explains the salt sensitivity of the replication system. Our results confirm the importance of this enzyme for DNA replication.
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PMID:Replication of simian virus 40 chromatin in vitro depends on the amount of DNA polymerase alpha associated with replicating chromatin. 625 Aug 39

2,2'-Anhydro-1-(3'-O-acetyl-beta-D-arabinofuranosyl)-5-iodocytosine (anhydro-araIC 3'-acetate), previously synthesized and isolated as a crude product by Moffatt and his coworkers, was purified and characterized. The availability of pure anhydro-araIC 3'-acetate made possible a comparative study of the antineoplastic, antiviral and biochemical potencies of anhydro-araIC 3'-acetate with the structurally related agents 2,2'-anhydro-1-(3'-O-acetyl-beta-D-arabinofuranosyl)cytosine (anhydro-araC 3'-acetate) and 2,2'-anhydro-1-(beta-D-arabinofuranosyl)-5-iodocytosine (anhydro-araIC). The presence of the 5-iodo substituent and/or the 3'-O-acetyl group on 2,2'-anhydro1-(beta-D-arabinofuranosyl)cytosine (anhydro-araC) did not alter the capacity of these agents to exert cytotoxic and antineoplastic activity against L1210, P388, L5178Y and human leukemia cells and against human colon and rectal carcinomas, as well as antiviral activity against herpes simplex virus Type 1. All of the compounds caused inhibition of [3H]thymidine incorporation into the DNA of L1210 cells in culture, with anhydro-araIC 3'-acetate being significantly less inhibitory than the other derivatives. Little or no interference with RNA and protein synthesis was produced by these pyrimidine nucleosides. Both anhydro-araIC 3'-acetate and anhydro-araIC were potent inhibitors of the activity of DNA polymerase alpha from the L1210 leukemia at the nucleoside level, while anhydro-araC 3'-acetate and anhydroaraC were non-inhibitory; none of the agents caused inactivation of DNA polymerase beta. The findings suggest that the antineoplastic and antiviral activities of the 2,2'-anhydro-arabinosylcytosine nucleosides may be the result of biochemical actions different from those of araC.
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PMID:Evaluation of 2,2'-anhydro-1-(3'-Ok-acetyl-beta-D-arabinofuranosyl)-5-iodocytosine hydrochloride and related compounds as antineoplastic and antiviral agents. 625 5

We have determined the levels of cellular DNA polymerases and Epstein-Barr virus specific DNA polymerase in three Burkitt's lymphoma cell lines producing varying amounts of EBV, one of which was induced by 12-0-tetra-decanoylphorbol-13-acetate (TPA). There was a proportional increase in the level of EBV-DNA polymerase with an increase in the percent of virus-producing cells. However, there was a reciprocal relationship between the levels of EBV-DNA polymerase and DNA polymerase alpha i.e., in cell line containing the highest level of EBV-DNA polymerase, activity of DNA polymerase alpha, but not of DNA polymerase beta, was reduced to an insignificantly low level. TPA does not have any direct effect on activities of either EBV-DNA polymerase or DNA polymerase alpha. EBV-DNA polymerases isolated from cells grown with or without TPA are indistinguishable in their properties such as elution position on phosphocellulose column, molecular weight, mono and divalent cation requirements, pH optimum, and other requirements for optimum activity. Addition of crude extracts of cells grown in presence of TPA to the purified DNA polymerase alpha did not inhibit its activity indicating that the observed loss was not due to any specific inhibitor present in TPA treated cells. Raji, a nonproducer cell line, did not contain EBV-DNA polymerase. There was no induction of EBV-DNA polymerase when Raji cells were grown in presence of TPA. The phenomenon of reduction in the levels of DNA polymerase alpha in cells induced to produce EBV may represent a mechanism by which the host DNA replication is shut off following virus infection.
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PMID:Cellular and Epstein-Barr virus specific DNA polymerases in virus-producing Burkitt's lymphoma cell lines. 628 81


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