Effects of 2′,3′‐dideoxynucleosides on mammalian cells and viruses

Waqar, M. Anwar; Evans, Marcus; Manly, Kenneth F.; Hughes, Robert G.; Huberman, Joel A.

doi:10.1002/jcp.1041210218

Cited by 127 publications

(70 citation statements)

References 21 publications

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“…These results indicate that the process being measured in the extracts is energy dependent, is enhanced by the addition of deoxynucleotides, and is sensitive to aphidicolin and dideoxynucleotides, which are agents known to inhibit DNA polymerases (3,16,21,22). Taken together, these results suggest that at least one aspect of the activity in the extracts involves DNA polymerization.…”

Section: Downloaded Frommentioning

confidence: 73%

DNA mismatch repair detected in human cell extracts.

Glazer¹,

Sarkar²,

Chisholm³

et al. 1987

Mol. Cell. Biol.

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A system to study mismatch repair in vitro in HeLa cell extracts was developed. Preformed heteroduplex plasmid DNA containing two single base pair mismatches within the SupF gene of Escherichia coli was used as a substrate in a mismatch repair assay. Repair of one or both of the mismatches to the wild-type sequence was measured by transformation of a lac(Am) E. colh strain in which the presence of an active supF gene could be scored. The E. coli strain used was constructed to carry mutations in genes associated with mismatch repair and recombination (mutH, mutU, and recA) so that the processing of the heteroduplex DNA by the bacterium was minimal. Extract reactions were carried out by the incubation of the heteroduplex plasmnid DNA in the HeLa cell extracts to which ATP, creatine phosphate, creatine kinase, deoxynucleotides, and a magnesiumcontaining buffer were added. Under these conditions about 1% of the mismatches were repaired. In the absence of added energy sources or deoxynucleotides, the activity in the extracts was significantly reduced. The addition of either aphidicolin or dideox nucleotides reduced the mismatch repair activity, but only aphidicolin was effective in blocking DNA polymerization in the extracts. It is concluded that mismatch repair in these extracts is an energy-requiring process that is dependent on an adequate deoxynucleotide concentration. The results also indicate that the process is associated with some type of DNA polymerization, but the different effects of aphidicolin and dideoxynucleotides suggest that the mismatch repair activity in the extracts cannot simply be accounted for by random nick-translation activity alone.The repair of base pair mismatches in the DNA of an organism plays an important role in reducing the frequency of mutations and in preserving the genetic integrity of the organism. Mismatches can occur in several ways. Recombination events can generate heteroduplex regions in DNA, and the process of gene conversion is thought to involve heteroduplex structures as intermediates. In DNA replication errors can occur which produce mismatched bases that must be corrected to avoid a high rate of spontaneous mutagenesis.In Escherichia coli DNA mismatch repair has been studied extensively. Transfection experiments with heteroduplex bacteriophage DNA (for a review, see reference 11) have demonstrated that E. coli has an efficient system for mismatch repair. The power of procaryotic genetic analysis has allowed identification of mutants that are deficient in various aspects of the repair process, and this has led to an understanding of some of the mechanisms that are involved. The products of the mutH, mutL, mutS, and mutU loci all seem to play a role in mismatch repair. Mutations at these loci produce strains that undergo a high rate of spontaneous mutagenesis because they cannot repair DNA mismatches effectively (11). Experiments involving the transfection of E. coli with hemimethylated A DNA coupled with the identification of mutants with altered function in the methylas...

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Section: Downloaded Frommentioning

confidence: 73%

DNA mismatch repair detected in human cell extracts.

Glazer¹,

Sarkar²,

Chisholm³

et al. 1987

Mol. Cell. Biol.

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“…These drugs have two mechanisms in their inhibition of HIV replication. Firstly they compete with endogenous deoxynucleoside-5'-triphosphates for the viral reverse transcriptase and secondly, once incorporated into proviral DNA, they cause chain termination of the DNA strand (Waqar et al, 1984;Mitsuya and Broder, 1986;Mukherji et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Zalcitabine (ddC) Phosphorylation and Drug Interactions

Veal

Barry

Back

1995

Antivir Chem Chemother

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SummaryZalcitabine (2',3'-dideoxycytidine; ddC) is an inhibitor of HIV reverse transcriptase. The intracellular metabolism of ddC in peripheral blood mononuclear cells (PBMCs), U937 cells and Molt 4 cells were investigated, and phosphate metabolites were determined by on-line radiometric HPLC. Comparable levels of all three ddC phosphate metabolites were formed in PHA-stimulated PBMCs, U937 cells and Molt 4 cells.Zidovudine (ZDV), didanosine (ddl) and stavudine (d4T) had no significant effect on ddC (O.06JlM) phosphorylation in PBMCs whereas the endogenous nucleoside, cytidine decreased phosphorylation in a concentration-dependent manner (e.g. 41% inhibition of total phosphate formation at 6JlM cytidine, 85% inhibition at 60JlM).The cytotoxic anticancer drug doxorubicin caused a decrease in ddC phosphorylation in U937/Moit 4 cells (e.g. 56% inhibition of total phosphate formation in U937 cells; 55% in Molt 4 cells at a doxorubicin concentration of 60JlM), whilst the antiviral agent ribavirin exhibited no inhibitory effects.

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“…Like the triphosphates of other dideoxynucleosides, ddATP competitively inhibits HIV reverse transcriptase and acts as a chain terminator for proviral DNA (524). Human DNA polymerase alpha is relatively resistant to ddATP, but polymerases beta and gamma are more sensitive to it (496), perhaps accounting for some of the toxicity seen in patients. In vitro, ddl is less potent against HIV than dideoxycytidine (ddC) (315), but intracellularly ddATP is as active as zidovudine (344), and it has an intracellular half-life of 8 to 12 h (compared with about 3 h for zidovudine [1,227] Investigational Antiretroviral Agents Many compounds are under investigation as candidate drugs for the management of HIV infection.…”

Section: Zidovudinementioning

confidence: 99%

Antiviral therapy: current concepts and practices

Bean

1992

Clin Microbiol Rev

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Drugs capable of inhibiting viruses in vitro were described in the 1950s, but real progress was not made until the 1970s, when agents capable of inhibiting virus-specific enzymes were first identified. The last decade has seen rapid progress in both our understanding of antiviral therapy and the number of antiviral agents on the market. Amantadine and ribavirin are available for treatment of viral respiratory infections. Vidarabine, acyclovir, ganciclovir, and foscarnet are used for systemic treatment of herpesvirus infections, while ophthalmic preparations of idoxuridine, trifluorothymidine, and vidarabine are available for herpes keratitis. For treatment of human immunodeficiency virus infections, zidovudine and didanosine are used. Immunomodulators, such as interferons and colony-stimulating factors, and immunoglobulins are being used increasingly for viral illnesses. While resistance to antiviral drugs has been seen, especially among AIDS patients, it has not become widespread and is being intensely studied. Increasingly, combinations of agents are being used: to achieve synergistic inhibition of viruses, to delay or prevent resistance, and to decrease dosages of toxic drugs. New approaches, such as liposomes carrying antiviral drugs and computer-aided drug design, are exciting and promising prospects for the future.

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Effects of 2′,3′‐dideoxynucleosides on mammalian cells and viruses

Cited by 127 publications

References 21 publications

DNA mismatch repair detected in human cell extracts.

DNA mismatch repair detected in human cell extracts.

Zalcitabine (ddC) Phosphorylation and Drug Interactions

Antiviral therapy: current concepts and practices

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