Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1-beta-d-Arabinofuranosylthymine (ara-T), a metabolite of the sponge Tethya crypta, has shown selective activity against herpes simplex virus (HSV) replication (G. A. Gentry and J. F. Aswell, Virology 65:294-296, 1975). Analysis of HSV-infected and uninfected cell lysates by CsCl isopycnic centrifugation showed that ara-T blocked the incorporation of [(3)H]hypoxanthine into viral deoxyribonucleic acid and, to a large extent, into host deoxyribonucleic acid of infected (but not uninfected) cells. Additional experiments with [gamma-(32)P]adenosine 5'-triphosphate as a radiophosphate donor demonstrated that ara-T is phosphorylated by extracts of HSV-infected BHK cells and not by those of uninfected cells. At an ara-T concentration that almost completely inhibited the growth of LM cells, which had been transformed to a pyrimidine deoxyribonucleoside kinase(+) (dPyK(+)) phenotype by ultraviolet-inactivated HSV-1, the growth of uninfected LM cells was not affected. These results indicate that the viral dPyK is responsible for the selective antiviral activity of ara-T. This conclusion was further supported by experiments that showed that the replication of a variety of dPyK(-) mutants of HSV-1 and HSV-2 were not affected by ara-T and that ara-T inhibited the phosphorylation of deoxycytidine and deoxythymidine by HSV-1 dPyK, but not by host deoxycytidine and deoxythymidine kinases, respectively. Ara-T also selectively inhibited the replication of equine herpesvirus type 1 (EHV-1) in vitro and was effective against EHV-1 infection in vivo in hamsters. Further, EHV-1 was inhibited by ara-T and by bromodeoxyuridine in LM cells lacking a cytosol thymidine kinase, suggesting that EHV-1 induces a dPyK. Finally, spectrophotometric assay for thymine suggested that ara-T is not a substrate for nucleoside phosphorylase of hamster liver, and a microbiological assay indicated that substantial amounts of ara-T were excreted in the urine of uninfected hamsters that had received a single injection of 5 mg of ara-T, the amount given in each injection in the in vivo experiments with EHV-1.
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PMID:Antiviral activity of arabinosylthymine in herpesviral replication: mechanism of action in vivo and in vitro. 19 86

The naturally occurring nucleoside analogue arabinosyl thymidine is known as an anti-herpes and anti-cancer agent. The biologically active form is arabinosyl thymidine triphosphate (Ara-TTP), which inhibits cellular and viral DNA-polymerases and thus interferes with DNA replication. Using two murine erythroleukemia cell lines, Friend cell clone F4-6 and F4-12N, the latter being thymidine kinase deficient (TK-) cells transformed to a TK+ phenotype with the HSV TK gene, we have determined 1) the role of cellular and herpes simplex virus thymidine kinase (HSV TK) in the uptake of Ara-T into the cells; 2) the subsequent phosphorylation of intracellular Ara-T to Ara-TMP, Ara-TDP and Ara-TTP; 3) the incorporation of Ara-TTP into the DNA. Incorporation into DNA was studied under different conditions, including selective inhibition of the different cellular DNA polymerases by aphidicolin (that inhibits polymerases alpha and delta) and dideoxythymidine (that preferentially inhibits polymerases beta and gamma). The uptake of Ara-T into the methanol soluble pool of the cells depends upon its phosphorylation to Ara-TMP, which is more efficiently performed by the HSV TK than by the cellular TK, thus explaining the sensitivity of HSV infected cells to Ara-T. However, using increasing concentrations of Ara-T, we have shown that phosphorylation also occurs in normal control cells due to the cellular thymidine kinase. More than 90% of Ara-T is phosphorylated in the cell, and more than 60% of total Ara-T(MP, DP, TP) exists in the triphosphate form.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Arabinose furanosyl thymidine: uptake, phosphorylation and incorporation into DNA of mammalian cells. 196 22

Sensitivity of Herpes Simplex Virus type I (HSV-I) mutants carrying genetic defect in the DNA polymerase and thymidine kinase genes to the action of some drugs was studied. TK- mutant of HSV-I was resistant to Ara-T and ACG and sensitive to PAA, Ara-A as well as to ribavirin and ADEA. PAAr mutant of HSV-I was resistant to PAA, Ara-A, ACG and sensitive to Ara-T, ribavirin and ADEA. A double mutant of HSV-I-TK-, PAAr was resistant to all drugs, except for ribavirin and ADEA. To inhibit reproduction of HSV with genetic defect, it is important using drugs of independent mode of action on the function of defective viral gene.
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PMID:[Inhibition of the reproduction of a herpes simplex I virus carrying mutations in the thymidine kinase and DNA polymerase genes]. 301 23

1-beta-D-Arabinofuranosylthymine (araT) is a selective inhibitor of Epstein-Barr virus replication induced in both thymidine kinase (TK)-negative (TK-) and TK+ variants of the lymphoid cell line P3HR-I. This analog has no effect on the growth of noninduced cells (T. Ooka and A. Calender, Virology 104:219-223, 1980). The synthesis of early antigens is not affected by the analog, whereas that of late viral capsid antigens is completely inhibited, as demonstrated by the indirect immunofluorescence technique; kinetic reassociation experiments have also shown that araT strongly inhibits replication of viral DNA. Phosphorylation of the tritiated form of the analog ([3H]araT) was analyzed by thin-layer chromatography in cultures of control and induced cells, and the results demonstrated that only induced cells can convert the analog to the triphosphate form. These results indicate that the selective effect of araT in induced cells is probably related to a new virally induced TK activity. Preliminary characterization of this new activity has shown that it is able to phosphorylate the analog specifically, whereas cellular TKs cannot. araTTP, a final phosphorylation product of araT, is a potent inhibitor of Epstein-Barr virus-specific DNA polymerase, suggesting a possible inhibitory action of this product on Epstein-Barr virus replication.
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PMID:Effect of arabinofuranosylthymine on the replication of Epstein-Barr virus and relationship with a new induced thymidine kinase activity. 629 56

Cellular models of mitochondrial thymidine kinase (TK2) deficiency require a reliable method to measure TK2 activity in whole cell extracts containing two interfering deoxyribonucleoside kinases, thymidine kinase 1 (TK1) and deoxycytidine kinase. We tested the value of the thymidine analog (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) as a TK2-specific substrate. With extracts of OSTTK1- cells containing TK2 as the only thymidine kinase and a highly specific TK2 inhibitor we established conditions to detect the low TK2 activity commonly present in cells. With extracts of TK1-proficient osteosarcoma cells and normal human fibroblasts we showed that BVDU, but not 1-(beta-d-arabinofuranosyl)thymine (Ara-T), discriminates TK2 activity even in the presence of 100-fold excess TK1. A comparison with current procedures based on TK2 inhibition demonstrated the better performance of the new TK2 assay. When cultured human fibroblasts passed from proliferation to quiescence TK2 activity increased by 3-fold, stressing the importance of TK2 function in the absence of TK1.
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PMID:Bromovinyl-deoxyuridine: A selective substrate for mitochondrial thymidine kinase in cell extracts. 1663 May 72

Novel N1-substituted thymine derivatives related to 1-[(Z)-4-(triphenylmethoxy)-2-butenyl]thymine have been synthesized and evaluated against thymidine kinase-2 (TK-2) and related nucleoside kinases [i.e., Drosophila melanogaster deoxynucleoside kinase (Dm-dNK) and herpes simplex virus type 1 thymidine kinase (HSV-1 TK)]. The thymine base has been tethered to a distal triphenylmethoxy moiety through a polymethylene chain (n = 3-8) or through a (2-ethoxy)ethyl spacer. Moreover, substitutions at position 4 of one of the phenyl rings of the triphenylmethoxy moiety have been performed. Compounds with a hexamethylene spacer (18, 26b, 31) displayed the highest inhibitory values against TK-2 (IC50 = 0.3-0.5 microM). Compound 26b competitively inhibited TK-2 with respect to thymidine and uncompetitively with respect to ATP. A rationale for the biological data was provided by docking some representative inhibitors into a homology-based model of human TK-2. Moreover, two of the most potent TK-2 inhibitors (18 and 26b) that also inhibit HSV-1 TK were able to reverse the cytostatic activity of 1-(beta-D-arabinofuranosyl)thymine (Ara-T) and ganciclovir in HSV-1 TK-expressing OST-TK-/HSV-1 TK+ cell cultures.
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PMID:N1-substituted thymine derivatives as mitochondrial thymidine kinase (TK-2) inhibitors. 1718 Nov 58