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)

By the method of sedimentation in 5-20% alkaline sucrose gradient, the process of maturation of the nascent DNA fragment was studied with cultured mouse FM3A cells treated with 8-methoxypsoralen plus near-ultraviolet radiation. This treatment is known to cause crosslinks of the chromosomal DNA strands. The profile of the newly-replicated DNA, labeled for 10 min with [3H]thymidine immediately after treatment, was the same as that of the untreated cells, where the incorporated radioactivity was present in the intermediate DNA fragment (about 50-80 S). But, when the treated cells were labeled after several hours of incubation, the labeled DNA became much shorter due to inhibition of maturation of the initial DNA fragment (the Okazaki fragment) to the intermediate DNA. With the use of aphidicolin, a specific inhibitor of eukaryotic DNA polymerase alpha, it became apparent that, in addition to formation of the crosslinks, further DNA replication is required to cause this inhibition of DNA maturation. Aphidicolin also suppressed the inhibition of incorporation of [3H]thymidine into cellular DNA after treatment, but inhibition of this incorporation resumed after its removal.
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PMID:Maturation of nascent DNA fragment is disturbed after treatment of cultured mouse FM3A cells with 8-methoxypsoralen plus near-ultraviolet radiation. 640 87

dNTP pools are quite low in immature oocytes of the starfish, expand during the 1-methyladenine-induced maturational process and thereafter reach a maximal level (approx. 35, 20, 15 and 5 fmoles/egg for dTTP, dCTP, dATP and dGTP, respectively) which is maintained in overmatured eggs. Maturing oocytes were inseminated at the stage just before extrusion of the first polar body and determination of dNTP pools during early embryogenesis showed the same expansion pattern as that of the 1-methyladenine-treated oocytes. Therefore, the increase in dNTP pools during early embryogenesis is dependent on 1-methyladenine (1-MA) but independent of fertilization. Aphidicolin, a specific inhibitor of eukaryotic DNA polymerase alpha, has no effect on dNTP pool size in 1-methyladenine-treated oocytes, but causes considerable expansion of dNTP pools in fertilized eggs which cleave achromosomally in the presence of the drug.
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PMID:Changes in deoxyribonucleoside triphosphate pools in the starfish oocyte during maturation and early embryogenesis. 640 50

Aphidicolin, a potent and specific inhibitor of eukaryotic DNA polymerase alpha, has been reported to inhibit repair DNA synthesis in ultraviolet-irradiated, normal human fibroblasts but not in HeLa cells. By the use of assays for repair other than the measurement of repair synthesis, it is shown here that repair in HeLa cells is in fact susceptible to aphidicolin. Severe inhibition of DNA repair, with failure of individual repair events to be completed, and a smaller number of lesions removed, can occur even though repair synthesis continues.
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PMID:DNA repair in ultraviolet-irradiated HeLa cells is disrupted by aphidicolin. The inhibition of repair need not imply the absence of repair synthesis. 641 8

Aphidicolin, a fungal metabolite which is a specific inhibitor of DNA polymerase alpha, inhibited the incorporation of [14C]acetate into desmosterol in mouse L cells by 50% at a concentration of 8.8 microM. It had no effect on acetate metabolism into fatty acids or CO2. The site of inhibition was determined to be distal to the formation of mevalonic acid since aphidicolin also inhibited the incorporation of [14C]mevalonolactone into desmosterol but had no effect on the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (EC 1.1.1.34) or the incorporation of [14C]acetate into total nonsaponifiable lipids. High pressure liquid chromotographic analysis of the distribution of radioactivity among the nonsaponifiable lipids formed from [14C]acetate in the presence of aphidicolin indicated an accumulation of lanosterol accompanied by a proportional decrease in radiolabeled desmosterol and two of its precursors, delta 5,7,24-cholestatrienol, and 4 alpha-methyl-delta 8,24-cholestadienol. In cells exposed to aphidicolin, lanosterol accumulation was rapid (15 min) and reversible after a 3-h exposure when cells were rinsed and fresh medium added. It was concluded that aphidicolin inhibits the conversion of lanosterol to C-27 sterols. Although the exact mechanism of this inhibition has not yet been determined, addition of aphidicolin to 20,000 X g supernatant fractions of mouse liver homogenates inhibited the incorporation of [14C]mevalonolactone into cholesterol in a concentration-dependent manner, suggesting that aphidicolin may act directly on one or more of the enzymatic steps involved in lanosterol demethylation. The ubiquitous occurrence of an aphidicolin binding site on eukaryotic DNA alpha polymerases and the inhibitory action of aphidicolin at a proposed secondary regulatory site in sterol biosynthesis (lanosterol metabolism) suggest that a naturally occurring compound may exist which can regulate both DNA replication and cholesterogenesis.
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PMID:Aphidicolin, a specific inhibitor of DNA polymerase alpha, inhibits conversion of lanosterol to C-27 sterols in mouse L cells. 642 79

The effect of 5-fluorouracil on the stability of DNA and the synthesis of DNA replication intermediates was analyzed in human colon adenocarcinoma cells. Density gradient analysis showed that some of the drug is incorporated into DNA. Moreover, DNA fragments are released when cells with drug-containing DNA are lysed in dilute alkali. The DNA fragments can be separated from the bulk DNA by agarose gel electrophoresis. The fragmentation of the DNA can be prevented by pretreatment with aphidicolin which inhibits DNA polymerase alpha. In 5-fluorouracil-treated cells, a heterogeneous population of DNA replication intermediates is formed, instead of discrete DNA replication intermediates which are formed in untreated cells. Aphidicolin prevents the formation of the heterogeneous population of DNA fragments. However, replication intermediates formed before the blockade with aphidicolin are ligated to high-molecular-weight DNA. In cells released from aphidicolin inhibition, there is preferential labeling of the heterogeneous population of DNA fragments. This population, therefore, shows the same characteristics as the discrete DNA populations formed in untreated cells.
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PMID:Interaction between 5-fluorouracil and DNA of human colon adenocarcinoma. 643 May 49

Aphidicolin, a specific inhibitor of DNA polymerase alpha, is known to induce chromosomal aberrations. At concentrations that did not greatly affect mitotic index, aphidicolin induced a striking number of chromosome gaps and breaks distributed in a highly nonrandom manner in cultured human lymphocytes. Specific chromosome bands, especially 2q31, 3p14, 6q26, 7q32, 16q23, and Xp22 were preferentially damaged in lymphocytes from each of 12 subjects studied. Total and site-specific damage was dose dependent and greatly increased when folic acid was removed from the medium. The sites most sensitive to aphidicolin damage include the "hot spots" seen under conditions of thymidylate stress and in studies of spontaneous chromosomal damage. The fragile X site, which can also be induced by thymidylate stress, was not induced by aphidicolin in lymphocytes, suggesting a separate mechanism for its induction. Aphidicolin represents a novel tool for detection of hot spots on human chromosomes through the mechanism of DNA polymerase alpha inhibition. The hot spots induced by aphidicolin represent a new class of fragile sites which we term common fragile sites.
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PMID:DNA polymerase alpha inhibition by aphidicolin induces gaps and breaks at common fragile sites in human chromosomes. 643 Jul 83

In vivo in mammalian cells, ultraviolet-induced unscheduled DNA synthesis was less sensitive to aphidicolin than was replicative DNA synthesis. Replicative DNA synthesis in HeLa, HEp-2, WI-38 VA-13 and CV-1 cells was inhibited more than 97% by aphidicolin at 10 micrograms/ml, whereas aphidicolin inhibition of DNA synthesis in ultraviolet-irradiated cells varied between 30% and 90% depending on cell types and assay conditions. Aphidicolin inhibition of unscheduled DNA synthesis (UDS) in HeLa cells increased gradually with increasing aphidicolin concentration and reached approximately 90% at 100 micrograms/ml aphidicolin. A significant fraction of UDS in ultraviolet-irradiated HEp-2 cells was resistant to aphidicolin even at 300 micrograms/ml. Considered along with related information reported previously, the present results suggest that both aphidicolin-sensitive and insensitive DNA polymerases, DNA polymerase alpha and a non-alpha DNA polymerase (possibly DNA polymerase beta), are involved in in situ UDS in these ultraviolet-irradiated cells. Comparison of staphylococcal nuclease sensitivity between DNAs repaired in the presence and in the absence of aphidicolin in HEp-2 cells suggested that the involvement of DNA polymerase alpha in UDS favored DNA synthesis in the intranucleosomal region.
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PMID:Differential sensitivity to aphidicolin of replicative DNA synthesis and ultraviolet-induced unscheduled DNA synthesis in vivo in mammalian cells. 643 54

The DNA polymerase activity in white matter, grey matter, and cerebellar regions of developing and aging rat brains was studied. The enzyme exhibited its highest activity during the early developmental stages with a decline to a low adult value by 225 days of age. However, the activity once again increased between 225 and 540 days, thus showing a second peak in the latter part of the life span. Studies with specific inhibitors like Aphidicolin and 2',3' dideoxy thymidine-5' triphosphate on the enzyme activity have revealed that this rise in the DNA polymerase activity in various regions studied was mainly due to an increase in the polymerase beta type. These results may explain the enhanced DNA content in aging rat brain observed earlier in this laboratory.
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PMID:Increased DNA polymerase beta-activity in different regions of aging rat brain. 643 6

Ap4A stimulated DNA synthesis when injected into oocytes. The stimulation was dramatically increased when an exogenous template was microinjected. Aphidicolin inhibited the effect of Ap4A, supporting a role of DNA polymerase alpha in this process. No stimulation by Ap4A was observed in microinjected eggs, nor ATP was able to mimic the in vivo effect of Ap4A. Besides microinjected activated DNA, the stimulation by Ap4A of DNA synthesis was also observed with poly dT and poly dT-poly dA as templates, while no effect was observed with poly dA- dT12 -18 and poly dC- dG12 -18. These results support a role of Ap4A in the initiation of DNA synthesis.
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PMID:Stimulation of DNA synthesis by microinjection of diadenosine 5',5''-P1, P4-tetraphosphate (Ap4A) into Xenopus laevis oocytes. 672 35

Aphidicolin, a known inhibitor of DNA polymerase alpha, is a potent inhibitor of nuclear DNA synthesis in HeLa cells but has no effect on the replication of mitochondrial DNA. Parallel experiments with mitochondria incubated in vitro also show no inhibition of DNA synthesis by aphidicolin; however, DNA synthesis in these isolated mitochondria is completely blocked by dideoxycytidine triphosphate, which inhibits DNA polymerase gamma but not the alpha polymerase. The replication of mitochondrial DNA therefore requires only one DNA polymerase of the gamma type.
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PMID:Mitochondrial DNA replication does not involve DNA polymerase alpha. 677 85


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