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Oxidative stress and certain environmental carcinogens, e.g. vinyl chloride and its metabolite chloroacetaldehyde (CAA), introduce promutagenic exocyclic adducts into DNA, among them 1,N6-ethenoadenine (εA), 3,N4-ethenocytosine (εC) and... more
Oxidative stress and certain environmental carcinogens, e.g. vinyl chloride and its metabolite chloroacetaldehyde (CAA), introduce promutagenic exocyclic adducts into DNA, among them 1,N6-ethenoadenine (εA), 3,N4-ethenocytosine (εC) and N2,3-ethenoguanine (εG). We studied se- quence-specific interaction of the vinyl-chloride metabolite CAA with human p53 gene exons 5-8, using DNA Polymerase Fingerprint Analysis (DPFA), and identified sites of the highest sensi - tivity.
Research Interests: Kinetics, DNA damage, DNA repair, Humans, Escherichia coli, and 13 morePolymerase Chain Reaction, Secondary Structure, Hot Spot, Acetaldehyde, Time Factors, Adaptive Response, Plasmid DNA, Full Length Movies, DNA Polymerase, Nucleotides, Biochemistry and cell biology, Molecular Structure, and Dna Synthesis
The broad spectrum of oxidative DNA damage biomarkers [urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) and 8-hydroxyguanine (8-OH-Gua)] and the level of oxidative DNA damage and repair in leukocytes DNA were analyzed in... more
The broad spectrum of oxidative DNA damage biomarkers [urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) and 8-hydroxyguanine (8-OH-Gua)] and the level of oxidative DNA damage and repair in leukocytes DNA were analyzed in three groups of subjects: (a) lung cancer patients [all smokers (n = 51)]; (b) healthy smokers with comparable smoking status (n = 26); and (c) healthy nonsmokers (n = 38). The mean level of 8-OH-Gua in urine samples of 38 healthy nonsmokers reached a value of 1.783 +/- 0.785 nmol/day/kg. This level was significantly lower than that in the urine of the two smoker groups (cancer patients and healthy smokers), in whom the levels reached values of 2.319 +/- 1.271 and 2.824 +/- 0.892 nmol/day/kg, respectively. Urinary excretion of 8-OH-dGuo was similar in all groups of subjects. The level of 8-OH-dGuo in DNA isolated from leukocytes of cancer patients was significantly higher than that in DNA isolated from the group of healthy smokers and nonsmokers (9.4...
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Subcutaneous application of aqueous wheat sprout extract to mice resulted in a slight decrease of the ability of fraction S-9 from their skin to activate DMBA to metabolites mutagenic for S. typhimurium TA 98. Induction by benzo(a)pyrene... more
Subcutaneous application of aqueous wheat sprout extract to mice resulted in a slight decrease of the ability of fraction S-9 from their skin to activate DMBA to metabolites mutagenic for S. typhimurium TA 98. Induction by benzo(a)pyrene of sperm abnormalities in mice was diminished after oral administration of the wheat sprout extract; however, even high doses of the extract did not completely abolish the effect of benzo(a)pyrene on spermatozoa. In the carcinogenicity studies, the wheat sprout extract, when applied to mouse skin during the initiation phase, enhanced fourfold the induction of papillomas by DMBA and shortened the period of latency from 9 to 5 weeks.
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Research Interests:
TagA (3-methyladenine–DNA glycosylase I) excises 3-methyadenine and 3-methylguanine from alkylated DNA. The structure of this enzyme has not yet been determined experimentally. We propose a three-dimensional model of the TagA protein... more
TagA (3-methyladenine–DNA glycosylase I) excises 3-methyadenine and 3-methylguanine from alkylated DNA. The structure of this enzyme has not yet been determined experimentally. We propose a three-dimensional model of the TagA protein based on the threading algorithm. The model shows that TagA is a mostly α-helical protein, in agreement with circular dichroism measurements. None of the eight cysteines present in the
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Research Interests: Kinetics, DNA damage, DNA repair, DNA, Mutation, and 4 moreEscherichia coli, DNA methylation, Lipoproteins, and Adenine
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Two of the major products in DNA resulting from exposure to alkylating agents are 7-methylguanine and 3-methyladenine. N-methylpurine-DNA-glycosylase is required for excision of these lesions. Recently, the 3-methyladenine-DNA-glycosylase... more
Two of the major products in DNA resulting from exposure to alkylating agents are 7-methylguanine and 3-methyladenine. N-methylpurine-DNA-glycosylase is required for excision of these lesions. Recently, the 3-methyladenine-DNA-glycosylase gene of Arabidopsis thaliana was cloned and shown to be involved only in repair of 3-methyladenine. In BY-2 tobacco cells, we showed an enzymatic activity which excised both 3-methyladenine and 7-methylguanine from methylated DNA.
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In living cells, there is a steady formation of DNA lesions. A substantial number of these lesions are formed by endogenous factors such as reactive oxygen species (ROS) that damage DNA on a continuous basis. Therefore, it is likely that... more
In living cells, there is a steady formation of DNA lesions. A substantial number of these lesions are formed by endogenous factors such as reactive oxygen species (ROS) that damage DNA on a continuous basis. Therefore, it is likely that ROS are the most important human carcinogens. An involvement of oxidative DNA damage, particularly 8-hydroxy-7, 8-dihydroguanine (8-OHGua) in the origin and/or progression of cancer is reviewed. It is concluded that severe oxidative stress manifested as an altered level of 8-OHGua in cellular DNA as well as in urine of cancer patients may be a consequence of development of many types of cancer. Although at present it is impossible to answer directly the question concerning involvement of oxidative DNA damage in cancer etiology it is very likely that oxidative DNA base modifications may serve as a source of mutations that initiate carcinogenesis (i.e., they may be causal factors responsible for the process). It should also be remembered that DNA damage, altered gene expression and mutations are required participants in the process of carcinogenesis. Although these events may be derived by different mechanisms a commonality is the involvement of oxidants in all these phenomena.
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Research Interests:
Background: The level of 8-oxoguanine (8-oxoG), a general marker of oxidative DNA damage, in DNA is the result of both an equilibrium between the rates of its formation and removal from DNA by DNA repair enzymes and the removal of... more
Background: The level of 8-oxoguanine (8-oxoG), a general marker of oxidative DNA damage, in DNA is the result of both an equilibrium between the rates of its formation and removal from DNA by DNA repair enzymes and the removal of 8-oxodGTP from the cellular nucleotide pool by hydroly- sis to 8-oxodGMP, preventing its incorporation into DNA. To determine the contribution
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One of the major lipid peroxidation products trans-4-hydroxy-2-nonenal (HNE), forms cyclic propano- or ethenoadducts bearing six- or seven-carbon atom side chains to... more
One of the major lipid peroxidation products trans-4-hydroxy-2-nonenal (HNE), forms cyclic propano- or ethenoadducts bearing six- or seven-carbon atom side chains to G>C≫A>T. To specify the role of SOS DNA polymerases in HNE-induced mutations, we tested survival and mutation spectra in the lacZα gene of M13mp18 phage, whose DNA was treated in vitro with HNE, and which was grown in uvrA(-)Escherichia coli strains, carrying one, two or all three SOS DNA polymerases. When Pol IV was the only DNA SOS polymerase in the bacterial host, survival of HNE-treated M13 DNA was similar to, but mutation frequency was lower than in the strain containing all SOS DNA polymerases. When only Pol II or Pol V were present in host bacteria, phage survival decreased dramatically. Simultaneously, mutation frequency was substantially increased, but exclusively in the strain carrying only Pol V, suggesting that induction of mutations by HNE is mainly dependent on Pol V. To determine the role of Pol II and Pol IV in HNE induced mutagenesis, Pol II or Pol IV were expressed together with Pol V. This resulted in decrease of mutation frequency, suggesting that both enzymes can compete with Pol V, and bypass HNE-DNA adducts in an error-free manner. However, HNE-DNA adducts were easily bypassed by Pol IV and only infrequently by Pol II. Mutation spectrum established for strains expressing only Pol V, showed that in uvrA(-) bacteria the frequency of base substitutions and recombination increased in relation to NER proficient strains, particularly mutations at adenine sites. Among base substitutions A:T→C:G, A:T→G:C, G:C→A:T and G:C→T:A prevailed. The results suggest that Pol V can infrequently bypass HNE-DNA adducts inducing mutations at G, C and A sites, while bypass by Pol IV and Pol II is error-free, but for Pol II infrequent.
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Research Interests:
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Nucleotide-excision repair (NER) is important for the maintenance of genomic integrity and to prevent the onset of carcinogenesis. Oxidative stress was previously found to inhibit NER in vitro, and dietary antioxidants could thus protect... more
Nucleotide-excision repair (NER) is important for the maintenance of genomic integrity and to prevent the onset of carcinogenesis. Oxidative stress was previously found to inhibit NER in vitro, and dietary antioxidants could thus protect DNA not only by reducing levels of oxidative DNA damage, but also by protecting NER against oxidative stress-induced inhibition. To obtain further insight in the relation between oxidative stress and NER activity in vivo, oxidative stress was induced in newborn piglets by means of intra-muscular injection of iron (200mg) at day 3 after birth. Indeed, injection of iron significantly increased several markers of oxidative stress, such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) levels in colon DNA and urinary excretion of 8-oxo-7,8-dihydroguanine (8-oxoGua). In parallel, the influence of maternal supplementation with an antioxidant-enriched diet was investigated in their offspring. Supplementation resulted in reduced iron concentrations in the colon (P=0.004) at day 7 and a 40% reduction of 8-oxodG in colon DNA (P=0.044) at day 14 after birth. NER capacity in animals that did not receive antioxidants was significantly reduced to 32% at day 7 compared with the initial NER capacity on day 1 after birth. This reduction in NER capacity was less pronounced in antioxidant-supplemented piglets (69%). Overall, these data indicate that NER can be reduced by oxidative stress in vivo, which can be compensated for by antioxidant supplementation.
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The SUV3 gene is present in all eukaryotes and encodes an RNA/DNA helicase which operates both in mitochondria and cell nuclei. To assess its function in mammals we generated a mouse mutant strain in which the 3' part of the SUV3... more
The SUV3 gene is present in all eukaryotes and encodes an RNA/DNA helicase which operates both in mitochondria and cell nuclei. To assess its function in mammals we generated a mouse mutant strain in which the 3' part of the SUV3 gene is disrupted. The mutated allele is a hypomorph transmitted from one generation to another at a frequency about 35% lower than expected while mice homozygous for the mutation die in utero before midgestation. Using ELISA binding assays we show that human SUV3 protein interacts with human WRN and BLM helicases. The binding to BLM protein was 10-fold stronger (with a K(d) of 0.5nM) than to WRN protein (K(d) of 5nM). Silencing of the SUV3 gene in the human cell line HeLa resulted in elevation of homologous recombination as measured by the frequency of sister chromatid exchange during mitotic cell division. These results indicate that the SUV3 protein is required in mammalian development and in somatic cells participates in genome maintenance through ...
Research Interests: Gene Silencing, Cell Division, RNA interference, Mitosis, Cell line, and 14 moreHumans, Mice, Animals, Embryonic Stem Cells, Clinical Sciences, Protein Interaction, HeLa cells, Transfection, Homologous Recombination, Gestational Age, Amino Acid Sequence, Protein Binding, Somatic Cells, and RecQ Helicases
Oxidative stress and lipid peroxidation (LPO) accompanying infections and chronic inflammation may induce several human cancers. LPO products are characterized by carbohydrate chains of different length, reactive aldehyde groups and... more
Oxidative stress and lipid peroxidation (LPO) accompanying infections and chronic inflammation may induce several human cancers. LPO products are characterized by carbohydrate chains of different length, reactive aldehyde groups and double bonds, which make these molecules reactive to nucleic acids, proteins and cellular thiols. LPO-derived adducts to DNA bases form etheno-type and propano-type exocyclic rings, which have profound mutagenic potential, and are elevated in several cancer-prone diseases. Adducts of long chain LPO products to DNA bases inhibit transcription. Elimination from DNA of LPO-induced lesions is executed by several repair systems: base excision repair (BER), direct reversal by AlkB family proteins, nucleotide excision repair (NER) and recombination. Modifications of proteins with LPO products may regulate cellular processes like apoptosis, cell signalling and senescence. This review summarizes consequences of LPO products' presence in cell, particularly 4-hydroxy-2-nonenal, in terms of genomic stability.