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)

To study the antiproliferative response of B cells to interferon-alpha (IFN-alpha) at the molecular level, we developed a cell-free system to assess DNA synthesis in nuclei isolated from IFN-sensitive Daudi B lymphoblastoid cells. [3H]dTTP incorporation in isolated nuclei was shown to be representative of replicative DNA synthesis by evidence that (i) incorporation was dependent on ATP and all four nucleoside precursors, (ii) incorporation was inhibited greater than 97% by aphidicolin, a specific inhibitor of DNA polymerase alpha and delta, and (iii) the DNase I-sensitive product banded in neutral CsCl at a density indicative of replicative DNA. This cell-free model was used in conjunction with flow cytometric cell cycle analysis to determine the effect of IFN-alpha on DNA synthesis in Daudi cells. The addition of IFN-alpha to an IFN-growth sensitive Daudi subclone in G0/early G1 inhibited the initiation of DNA synthesis, assessed in isolated nuclei, and prevented the progression of cells into S phase. IFN-alpha failed to inhibit DNA synthesis or cell cycle progression when added to IFN-sensitive Daudi cells in late G1/early S phase or to an IFN-resistant Daudi subclone. These studies suggest that IFN-alpha inhibits DNA replication and cellular proliferation in Daudi B cells by interfering with G1 cell cycle events.
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PMID:DNA synthesis in nuclei isolated from Daudi B cells: a model to study the antiproliferative mechanisms of interferon-alpha. 157 80

A multiparametric analysis of the effects of human recombinant interferon alpha type A on Daudi cells involving flow cytometry and in vitro analysis of alpha and beta DNA polymerase activities has been performed. Results have disclosed (within 60 min of interferon treatment) a decrease of alpha polymerase driven DNA synthesis persisting to at least 24 h, while beta polymerase was poorly affected. Moreover, after 24 h of interferon treatment, a reduction of BrdUrd incorporation per cell, assessed by flow cytometry, was observed suggesting that DNA synthesis in S phase cells is almost completely abolished. The analysis of the effect of interferon on the distribution of cell cycle phases indicated that the G1/S transition is not inhibited by the treatment. These results support the hypothesis that interferon generates a transient initiating signal which quickly reaches the nucleus and produces a rapid inhibition of alpha polymerase activity, leading finally to the slowing of cell cycle progression.
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PMID:Interferon affects cell growth progression by modulating DNA polymerases activity. 159 35

The effects of r-TNF alpha on cell cycle progression and DNA polymerase activity in Daudi lymphoma cells have been analyzed. Cytofluorimetric analysis of the cell cycle after 6 to 24 hr of treatment revealed both a decrease of BrdU incorporation per cell and a light inhibition of S phase as assessed by the analysis of the percentual distribution of cell cycle compartments. The reduction of BrdU incorporation can be related to the early decrease in the rate of DNA synthesis that follows r-TNF alpha treatment. These results suggest that one of the early events induced by r-TNF alpha at nuclear level is the slowering of DNA synthesis leading to a reduced cell cycle progression.
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PMID:Nuclear metabolic changes induced by tumor necrosis factor in Daudi lymphoma cells; a multiparametric analysis. 180 6

The effect of human recombinant DNA interferon-alpha type A (rIFN alpha A) on nuclear lipid biosynthesis and on in vitro nucleic acid synthesis was investigated in Daudi lymphoma cells sensitive (Daudi Is) or resistant (Daudi Ir) to the antiproliferative activity of this glycoprotein. In the Daudi Is studied at 90 min and up to 8 h, relative proportions of 3H-labeled nuclear lipids were reproducibly altered as compared to controls: phosphatidylcholine increased while phosphatidylserine and total neutral lipids decreased. These changes were not detected in parallel studies of the whole cell extracts. No significant changes in the profiles of nuclear lipids were observed in Daudi Ir. Decreased rates of alpha DNA polymerase and of RNA transcription were evident within 90 min in the Daudi Is nuclei but not in untreated controls or nuclei from rIFN alpha A-treated Daudi Ir cells, thus suggesting a possible relationship of the rapid alterations of nuclear lipid biosynthesis in Daudi Is cells to the rIFN alpha A antiproliferative activity.
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PMID:Early modifications of nucleic acid metabolism and nuclear lipid biosynthesis associated with antiproliferative activity of interferon-alpha on Daudi lymphoma cells. 231 63

Human (h) interleukin-10 (IL-10) exhibits a strong DNA and amino acid sequence homology to the Epstein-Barr virus (EBV) BCRF1 genome, viral (v) IL-10. We analyzed the production of IL-10 for EBV activation in B-cell lines. The latent EBV in Akata cells was activated by the cross-linking of surface immunoglobulin G (IgG) with anti-human IgG. The levels of IL-10(h+v) and vIL-10 in the culture fluids were measured by a specific enzyme-linked immunosorbent assay (ELISA). IL-10(h+v) was detected at the same time for EBV immediate early gene BZLF1 product ZEBRA and early gene BMRF1 product EA-D. This was more than 4 hours prior to the appearance of vIL-10, and late gene products gp 350/220 and viral capsid antigen. The induction of hIL-10 and vIL-10 mRNAs were detected in anti-IgG-treated Akata cells by reverse transcription-polymerase chain reaction. The induction of IL-10(h+v) and vIL-10 was inhibited with a tyrosine kinase inhibitor, herbimycin, or with an inhibitor of herpesvirus DNA polymerase, phosphonoacetic acid, or acyclovir. IL-10(h+v) and vIL-10 were also detected in the supernatants of Akata and Daudi but not Ramos cells infected with P3HR-1 EBV. These results show the IL-10 induction on EBV activation in EBV-carrying B-cell lines.
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PMID:Induction of interleukin-10 on activation of Epstein-Barr virus in EBV-infected B-cell lines. 1018 89

Antigen stimulation induces a rapid proliferation of B cells for expansion of specific B cell clones and their further differentiation into antibody-producing cells in germinal centers of T-dependent antigen-immunized mice. Previously, we identified a 210-kDa germinal center-associated nuclear protein (GANP) that is up-regulated selectively in germinal centers and carries an MCM-binding domain in the carboxyl-terminal side. In addition, here, we found a region (from 414 to 550 aa) in GANP molecule that is slightly similar to the known DNA-primase component p49. The recombinant GANP fragment covering this region synthesizes RNA primers for extension by DNA polymerase I with single-stranded DNA templates in vitro. GANP DNA-primase activity is controlled by phosphorylation at Ser(502) that is induced by CD40-mediated signaling in vitro and in the germinal center B cells stimulated with antigen in vivo. Overexpression of ganp cDNA in Daudi B cells caused the increased DNA synthesis more than the levels of the mock-transfectants. These evidences suggested that the novel DNA-primase GANP is involved in regulation of cell proliferation of antigen-driven B cells in germinal centers.
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PMID:Germinal center-associated nuclear protein (GANP) has a phosphorylation-dependent DNA-primase activity that is up-regulated in germinal center regions. 1152 38

Psychological stress-associated immune dysregulation has been shown to disrupt the steady-state expression and reactivate latent herpes viruses. One such virus is the Epstein Barr virus (EBV), which is associated with several human malignancies. EBV infects >90% of people living in North America and persists for life in latently infected cells. Although several studies have shown that glucocorticoids (GCs) can directly induce reactivation of the latent virus, the mechanism of stress hormone involvement in the control of EBV gene expression is not well understood. In this study, we tested the hypothesis that GCs can induce the latent EBV genome to lytically replicate through the induction of the EBV immediate early gene BZLF1 which encodes the lytic transactivator protein ZEBRA. We show a dose-dependent upregulation of BZLF1 mRNA expression by hydrocortisone (HC) and dexamethasone (Dex) in Daudi cells, an EBV genome positive Burkitt's lymphoma cell line, and Dex-induction of the early gene products BLLF3 (encoding for the EBV dUTPase) and BALF5 (encoding for the EBV DNA polymerase). We show that Daudi cells express glucocorticoid receptors (GR) that mediate Dex-dependent upregulation of BZLF1 mRNA levels. This effect was inhibited by both the glucocorticoid receptor antagonist RU486 and by cycloheximide. The results suggest that GCs, in addition to inducing stress-related immune dysregulation, can mediate latent EBV reactivation through the induction of the BZLF1 gene.
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PMID:Glucocorticoids activate Epstein Barr virus lytic replication through the upregulation of immediate early BZLF1 gene expression. 2046 55