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:2.7.1.21 (thymidine kinase)
7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infection of monkey kidney (BSC-40) cells with vaccinia virus strain WR resulted in a marked increase in ribonucleoside diphosphate reductase (EC 1.17.4.1) activity as measured by CDP reduction in cell-free extracts. After a synchronous infection, increased activity was detected at 2 h, peaked at 4 to 5 h, and then declined between 6 and 8 h to the endogenous cellular level. The induction, detectable at 0.5 PFU/cell, correlated strongly with multiplicity of infection to 10 PFU/cell and continued to increase to 50 PFU/cell. It paralleled the previously described induction of viral DNA polymerase and thymidine kinase, suggesting that the reductase may also be a product of early transcription of the viral genome. The inhibition of DNA synthesis throughout infection resulted in prolonged accumulation of reductase activity and delayed and incomplete down-regulation at 8 h, suggesting that repression involves late functions. Rescue of fluorodeoxyuridine-inhibited DNA synthesis with exogenous thymidine restored the normal pattern. Preferential association of the induced reductase with the cytoplasmic sites of vaccinia virus DNA replication (virosomes) was not detected. The induced enzyme is similar in several respects to other eucaryotic ribonucleotide reductases, but is distinct from host cell reductase in response to certain modulators of reductase activity (M. B. Slabaugh and Christopher K. Mathews, J. Virol. 52:501-506, 1984). Full activity required an activator, exogenous reducing equivalents, and iron. Hydroxyurea, EDTA, dATP, and dTTP inhibited CDP reduction, setting this reductase apart from T4 reductase, which is not inhibited by dATP, and from herpesvirus reductase, which requires no activation and is insensitive to deoxyribonucleoside triphosphate inhibition.
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PMID:Vaccinia virus induces ribonucleotide reductase in primate cells. 638 75

The activities of ribonucleotide reductase and thymidine kinase, and the thymidine incorporation rate were measured in 16 cultured human hematologic malignant cell lines with different cell proliferation rates. Thymidine kinase activity was significantly higher in myeloid and monocytoid cell lines than in other cell lines, but ribonucleotide reductase activity presented as CDP reductase activity was similar in the different cell lines. The ratio of thymidine kinase to CDP reductase activity was high in monocytoid cell lines. A close correlation was found between the cell proliferation rate and CDP reductase activity, but not thymidine kinase activity or the thymidine incorporation rate. The ratio of thymidine kinase to CDP reductase activity was high in slowly growing cell lines and low in rapidly growing cell lines. These results indicate that in cultured human malignant cells a high potential for proliferation may depend mainly on the de novo pyrimidine pathway of DNA biosynthesis.
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PMID:Ribonucleotide reductase and thymidine kinase activities in various cultured cell lines derived from hematologic malignancies. 638 52

A series of forty 5'-ester derivatives of 5-ethyl-2'-deoxyuridine (EDU) have been evaluated for their inhibitory effects on the growth and metabolism of murine leukemia L1210 cells. Several EDU esters proved as potent as EDU in their inhibitory effects on L1210 cell growth (inhibitory dose-50:5-10 micrograms/ml), suggesting that these esters were readily hydrolyzed to release the parent compound EDU. That the EDU esters had to be hydrolyzed first to EDU was further suggested by the dependence of their antiproliferative action on the thymidine kinase activity of the cells. It was further ascertained that EDU and its esters acquired their antiproliferative effects by an interaction with dCTP biosynthesis, possibly at the CDP ribonucleotide reductase step. Under conditions where thymidine was readily incorporated, we were unable to demonstrate any incorporation of EDU into L1210 cell DNA.
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PMID:Antitumor cell and antimetabolic effects of 5-ethyl-2'-deoxyuridine and 5'-substituted 5-ethyl-2'-deoxyuridine derivatives. 646 97

Hydroxyurea when injected intraperitoneally into rats either as a single dose or as three consecutive daily doses, markedly inhibited thymidine kinase activity in cerebellum on 7th day. The inhibitory effect of the drug was found to be both dose and time dependent. The drug has however, failed to exert any inhibitory action when added to the reaction mixture in vitro. It is concluded that the well established inhibition on DNA synthesis by hydroxyurea may not be solely due to its action on ribonucleotide reductase (EC 1.17.4.1) but probably due to its interference at several other sites including thymidine kinase.
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PMID:Hydroxyurea inhibits thymidine kinase activity in developing rat cerebellum. 667 24

Hydroxyurea when injected intraperitoneally into rats either as a single dose or as three consecutive daily doses, markedly inhibited thymidine kinase activity in cerebellum on 7th day. The inhibitory effect of the drug was found to be both dose and time dependent. The drug has however, failed to exert any inhibitory action when added to the reaction mixture in vitro. It is concluded that the well established inhibition on DNA synthesis by hydroxyurea may not be solely due to its action on ribonucleotide reductase (EC 1.17.4.1) but probably due to its interference at several other sites including thymidine kinase.
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PMID:Hydroxyurea inhibits thymidine kinase activity in developing rat cerebellum. 667 19

We have selected and characterized a thymidine-sensitive S49 mutant line, MC-3-3. MC-3-3 cells are 35-fold more sensitive to the cytotoxic effects of thymidine and 15-fold more sensitive to the cytotoxic effects of 5-bromodeoxyuridine than wild type S49 cells. In contrast, the MC-3-3 mutant line does not exhibit increased sensitivity to the cytotoxic action of 5-fluorodeoxyuridine. The MC-3-3 mutant line possesses levels of thymidylate synthetase and thymidine kinase activity which are equivalent to the levels in wild type S49 cells, but the ribonucleotide reductase activity in MC-3-3 cells, using CDP as a substrate, is only 10-30% of that in wild type cells. Using ADP as a substrate, the ribonucleotide reductase activity in permeabilized MC-3-3 cells is slightly higher than that in wild type S49 cells. The deoxyribonucleotide pools in exponentially growing MC-3-3 cells are approximately 40-50% of those in wild type S49 cells. By hybrid analysis, we determined that the thymidine sensitivity of the MC-3-3 cells is recessive. The MC-3-3 mutant line displays a rate of spontaneous mutation which is 15-30-fold higher than that of wild type S49 cells. The MC-3-3 mutant cells are also 5-10-fold more sensitive than wild type cells to the cytotoxic effects of tunicamycin and compactin. These results suggest that the MC-3-3 mutant line possesses a mutation in the dTTP binding site in ribonucleotide reductase; abnormal regulation of this enzyme results in an increase in the rate of spontaneous mutation.
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PMID:Mutator phenotype in a mutant of S49 mouse T-lymphoma cells with abnormal sensitivity to thymidine. 670 78

After a single intravenous administration of sturines A and B into rats subjected to partial hepatectomy, during the periods, corresponding to maximal synthesis of DNA, incorporation of 3H-thymidine into nuclear DNA was decreased by 20-30% and incorporation into mitochondrial DNA--by 40-50%, as compared with control. The treatment with sturines led to distinct decrease in activity of nuclear thymidine kinase and ribonucleotide reductase but did not affect the enzymatic activity in mitochondria. The sturine preparations (at concentrations 10(-6)--10(-3) M) inhibited the activity of these enzymes (of both nuclear and mitochondrial origin) in vitro.
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PMID:[Effect of sturines A and B on DNA synthesis and ribonucleotide reductase and thymidine kinase activity in regenerating rat liver]. 700 2

cis-Malonato-diammino platinum(II) significantly inhibited P-388 lymphocytic leukemia cell proliferation at 10 mg/kg/day. Incorporation studies showed that DNA synthesis was inhibited following in vivo drug therapy. The major inhibitory effects appeared to be on thymidine kinase and dihydrofolate reductase activities and on overall purine synthesis, with marginal effects on DNA polymerase and ribonucleotide reductase activities. In addition to the DNA inhibition, a marked increase in cyclic adenosine 3',5'-monophosphate levels was noted, which correlated with a rapid decrease in histone phosphorylation. Other minor effects of the drug included significant reduction of proteolytic activity, suppression of States 4 and 3 respiration, and an increase in adenosine triphosphatase and acid phosphatase activities of P-388 cells.
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PMID:Effects of cis-malonato-diammino platinum (II) on P-388 lymphocytic leukemia cell metabolism. 742 Feb 82

Herpes simplex virus (HSV) mutants or recombinant vectors might be useful oncolytic agents. Three general types of HSV vectors can be potentially used for this purpose: (1) mutants in viral transcription factors, such as ICP0 and ICP4; (2) mutants in enzymes involved in nucleic acid metabolism, such as thymidine kinase (TK) and ribonucleotide reductase (RR); and (3) mutants in neurovirulence factors, such as gamma 34.5. We tested the destructive ability of each type against rat 9L gliosarcoma cells in culture. We found that the HSV vectors defective in TK or RR were more efficient at tumor cell lysis in culture than the other types of HSV vectors. This increased efficiency provided the rationale for evaluating the TK and RR mutants in vivo following their stereotactic inoculation into 9L gliosarcomas implanted in rat brains. We employed the X-gal enzymatic histochemical assay to show that HSV-mediated lacZ gene expression was present in cells within the tumor mass in a relatively selective fashion. Immunoreactive HSV capsid and core antigens were present both in cells within the tumor, as well as in cells such as neurons and astrocytes, directly adjacent to the tumor mass. Long-term survival studies revealed that rats treated with either the TK or RR mutant lived significantly longer than control rats (p = 0.014, Kruskal-Wallis one-way analysis of variance). These results indicate that HSV vectors, defective in enzymes needed in nucleic acid metabolism, can preferentially mediate lacZ gene expression in cells within the tumor. (ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antitumor activity and reporter gene transfer into rat brain neoplasms inoculated with herpes simplex virus vectors defective in thymidine kinase or ribonucleotide reductase. 758 98

Although a number of transfection experiments have suggested potential targets for the action of the E2F1 transcription factor, as is the case for many transcriptional regulatory proteins, the actual targets in their normal chromosomal environment have not been demonstrated. We have made use of a recombinant adenovirus containing the E2F1 cDNA to infect quiescent cells and then measure the activation of endogenous cellular genes as a consequence of E2F1 production. We find that many of the genes encoding S-phase-acting proteins previously suspected to be E2F targets, including DNA polymerase alpha, thymidylate synthase, proliferating cell nuclear antigen, and ribonucleotide reductase, are indeed induced by E2F1. Several other candidates, including the dihydrofolate reductase and thymidine kinase genes, were only minimally induced by E2F1. In addition to the S-phase genes, we also find that several genes believed to play regulatory roles in cell cycle progression, such as the cdc2, cyclin A, and B-myb genes, are also induced by E2F1. Moreover, the cyclin E gene is strongly induced by E2F1, thus defining an autoregulatory circuit since cyclin E-dependent kinase activity can stimulate E2F1 transcription, likely through the phosphorylation and inactivation of Rb and Rb family members. Finally, we also demonstrate that a G1 arrest brought about by gamma irradiation is overcome by the overexpression of E2F1 and that this coincides with the enhanced activation of key target genes, including the cyclin A and cyclin E genes.
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PMID:Cellular targets for activation by the E2F1 transcription factor include DNA synthesis- and G1/S-regulatory genes. 762 16


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