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)

The influence of aphidicolin on cell multiplication and DNA synthesis was examined using synchronous mouse mastocytoma P-815 cells. Aphidicolin was cytotoxic specifically to the cells of the S phase of the cell cycle. This cytotoxicity was reversed by appropriately washing the drug-treated cells, but not by the addition of deoxyribonucleosides. Aphidicolin, a potent inhibitor of DNA synthesis, selectively inhibited the activity of partially purified DNA polymerase alpha from the nucleus and the cytosol of mastocytoma cells, but did not affect the activity of DNA polymerase beta. Furthermore, aphidicolin had no effect on the synthesis of RNA and protein, and produced no changes in cell size at least for one generation.
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PMID:Aphidicolin: a specific inhibitor of DNA synthesis in synchronous mastocytoma P-815 cells. 677 40

Aphidicolin clearly discriminated replicative DNA synthesis from unscheduled DNA synthesis. Aphidicolin inhibited replicative DNA synthesis in permeable mouse ascites sarcoma cells. The mode of inhibition of aphidicolin was a mixed type with respect to deoxycytidine triphosphate but was non-competitive with respect to the other three deoxynucleoside triphosphates. Aphidicolin did not affect the activity of unscheduled DNA synthesis in either bleomycin-treated permeable sarcoma cells or isolated rat liver nuclei. Considering the difference in sensitivity of DNA polymerase alpha and beta to aphidicolin, and other related information reported previously, the results are compatible with the idea that DNA polymerase alpha is involved in replicative DNA synthesis and DNA polymerase beta in unscheduled DNA synthesis in the present systems.
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PMID:Differential effects of aphidicolin on replicative DNA synthesis and unscheduled DNA synthesis in permeable mouse sarcoma cells. 678 76

Aphidicolin, a tetracyclic diterpenoid antibiotic, is a specific inhibitor of DNA synthesis in vivo and DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) alpha of eukaryotic organisms. After ethyl methanesulfonate mutagenesis, we have recovered mutants of Drosophila melanogaster Schneider cell line no. 2 that grow at concentrations of aphidicolin that completely inhibit wild-type cells. The DNA polymerase alpha from one of these mutants, aph-10, is much more resistant to inhibition by the drug; the apparent Ki of the wild-type enzyme is 12 nM aphidicolin, whereas the apparent Ki of the aph-10 polymerase is more than 100 nM. (The apparent Km for dCTP is the same for both enzymes.) Another mutant, aph-13, overproduces DNA polymerase alpha at least 8-fold. The DNA polymerase of this mutant has the same apparent Km and Ki for dNTPs and aphidicolin as does wild-type polymerase.
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PMID:DNA polymerase alpha mutants from a Drosophila melanogaster cell line. 678 18

The technique of laser flow cytofluorometry has been used to monitor the arrival in G1 and the subsequent progression through the cell cycle of HTC cells accumulated in metaphase with colcemid alone or after treatment with hydroxyurea and Nocodazole. Under the experimental conditions used in this study, the latter procedure gives much better results, avoiding in particular the extensive formation of micronucleated cells. Aphidicolin, an inhibitor of DNA polymerase, in combination with Nocodazole, provides a useful method to tightly synchronize these cells at the G1/S border.
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PMID:Laser flow cytofluorometric analysis of HTC cells synchronized with hydroxyurea, nocodazole and aphidicolin. 679 26

Aphidicolin is a specific inhibitor of DNA polymerase alpha. Its influence of DNA repair has been studied in both normal and excision deficient xeroderma pigmentosum cells exposed to u.v. irradiation at 254 nm. Single strand DNA breaks accumulated in u.v. irradiated normal cells when the inhibitor was present. Such breaks were absent in both unirradiated normal cells and in u.v. irradiated excision efficient cells incubated with the compound. The data therefore indicate that aphidicolin prevents the rejoining of single strand breaks formed during the excision repair process and imply that DNA polymerase alpha is involved in the repair of DNA in human cells.
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PMID:Aphidicolin: an inhibitor of DNA repair in human fibroblasts. 679 60

Aphidicolin is a specific inhibitor of DNA polymerase alpha and blocks DNA synthesis in vivo. The inhibition of purified alpha-polymerase has been shown to be competitive with dCTP but not with the other three deoxynucleoside triphosphates (dNTPs). In order to study the various roles that the alpha-polymerase might play in DNA replication and/or repair, we have attempted to isolate Chinese hamster V79 cells that are resistant to aphidicolin. Four resistant mutants were isolated from BrdU--black light- and UV-mutagenized cells. None of the mutants isolated contains an alpha-polymerase that is resistant, in crude extract measurements, to aphidicolin. Three mutants isolated, however, were found to be resistant to araC. Two mutants tested were found to be sensitive to cytidine and have elevated levels of dCTP or all 4 dNTPs. These results indicate that they are nucleotide pool mutants instead of alpha-polymerase mutants. One mutant, aphr-4, is characterized by the following: (1) high level of dCTP; (2) thymidine (or CdR, UdR) auxotrophic; (3) sensitive to thymidine (and AdR, GdR); (4) slow-growing; (5) cytidine sensitive; (6) UV sensitive and hypermutable at the ouabain-resistant locus; and (7) a ninefold increase in frequency of chromatid gaps and breaks when cells are exposed to BrdU-containing medium. Revertants of aphr-4 which are partially aphidicolin-resistant and retain the first three characteristics listed above, but not the others, have been isolated. The appearance of this type of revertant indicates that either aphr-4 or its "revertant" is a double mutant.
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PMID:Isolation and characterization of a UV-sensitive hypermutable aphidicolin-resistant Chinese hamster cell line. 679 64

Aphidicolin is a selective inhibitor of DNA polymerase alpha. In contrast to earlier reports, the drug was found to inhibit DNA synthesis catalyzed by DNA polymerase alpha and isolated HeLa cell nuclei by a similar mechanism. For both systems aphidicolin primarily competed with dCTP incorporation. However, the apparent Vmax for dCTP incorporation was reduced by 50-60% at relatively low concentrations of aphidicolin, thus the mechanism of inhibition is complex. Furthermore, a 2-5 fold increase in apparent Km for dTTP was observed in the presence of aphidicolin, but the apparent Km values for dATP and dGTP were essentially unaltered. This, together with additional evidence, suggested that the mechanism of action of aphidicolin involves a strong competition with dCMP incorporation, a weaker competition with dTMP incorporation and very little, if any, competition with dGMP and dAMP incorporation.
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PMID:Aphidicolin inhibits DNA synthesis by DNA polymerase alpha and isolated nuclei by a similar mechanism. 679 95

The effect of aphidicolin, a specific inhibitor of DNA polymerase alpha, on size maturation of nascent DNA intermediates was studied in cultured rat fibroblast cells. Results provided the first evidence of DNA synthesis associated with merging of intermediates of larger than replicon size. Aphidicolin at a concentration (1.4 micrograms/ml) causing 90-95% inhibition of [3H]thymidine incorporation, resulted in accumulation of intermediates of nearly the same size as the replicon (2-5 x 10(-7) Da); although the synthesis of short nascent fragments (referred to as Okazaki fragments) continued in the presence of aphidicolin, the rate of their elongation to the replicon size was greatly decreased. On removal of aphidicolin, these accumulated intermediates merged into high-molecular-weight DNA. This merging of the intermediates was associated with DNA synthesis in gaps between adjacent intermediates, as revealed by photolysis of bromodeoxyuridine-DNA leader with long-wave ultraviolet light; when the cells had been pulse-labeled for 5 min with bromodeoxyuridine immediately after removal of the drug, the large DNA arising from aphidicolin-arrested intermediates was cut into fragments of the original size by long-wave ultraviolet light irradiation. The arrest of chain elongation at the replicon-size by aphidicolin might be due to inhibition of this DNA synthesis in gaps, because aphidicolin did not cause degradation of nascent DNAs.
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PMID:Arrest of chain growth of replicon-sized intermediates by aphidicolin during rat fibroblast cell chromosome replication. 680 39

Aphidicolin inhibits DNA replication and growth of all tested human and murine neoplastic cells including leukemic T- and B-lymphocytes and melanocarcinoma cells. The concentration of aphidicolin causing 50% inhibition of DNA synthesis in all of the tested neoplastic cell lines is similar to that necessary to inhibit DNA synthesis in HeLa cells by 50%. The mechanism of inhibition of DNA synthesis in neoplastic cells is again due to the inhibition of DNA polymerase alpha by aphidicolin. Aphidicolin at a concentration 100 times higher than that causing 50% inhibition of DNA synthesis and cell growth had no effect on total protein synthesis, on the secretion of immunoglobulins, or on the expression of HLA antigens which are involved in relevant phenomena of the immune response.
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PMID:Inhibition of DNA replication and growth of several human and murine neoplastic cells by aphidicolin without detectable effect upon synthesis of immunoglobulins and HLA antigens. 680 14

The murine gene Fv-1 exerts a major control over the replication of Friend murine leukemia virus (F-MuLV). An effect of the gene product has been determined to be at the level of accumulation and integration of viral DNA. Aphidicolin, an inhibitor of eucaryotic DNA polymerase alpha, was studied in murine cells infected either permissively or nonpermissively with regard to the Fv-1 genotype. Results indicated that inhibition of DNA polymerase alpha did not affect the accumulation of form III viral DNA in either permissive or nonpermissive cells. However, the normal accumulation of circular form I DNA in permissive cells was inhibited. The block in the accumulation of form I DNA resembled that occurring in some F-MuLV Fv-1-nonpermissive infections. Additionally, aphidicolin treatment resulted in the accumulation of novel low-molecular-weight viral DNA species, normally detectable in a nonpermissive infection of NIH cells with B-tropic F-MuLV. These data suggest that the Fv-1 gene product may interact with host DNA polymerase alpha to prevent viral replication.
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PMID:Studies with aphidicolin on the Fv-1 host restriction of Friend murine leukemia virus. 680 56


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