1
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Louzon M, de Vaufleury A, Capelli N. Ecogenotoxicity assessment with land snails: A mini-review. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2023; 792:108472. [PMID: 37690511 DOI: 10.1016/j.mrrev.2023.108472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 09/12/2023]
Abstract
In the context of the increasing environmental and sanitary crisis, it is accepted that soil pollution can cause health alterations and disturb natural population dynamics. Consequently, the assessment of the genotoxic potential of compounds found in contaminated soils is important. Indeed, the alteration of genomic integrity may increase the risk of cancer development and may impair reproduction and long-term population dynamics. Among the methodologies to assess terrestrial genotoxic potential, there has been growing interest during the last decade in monitoring alterations of the genome in bioindicators of soil quality. As some land snail species are recognized bioindicators of soil quality, especially to assess the environmental and toxicological bioavailability of compounds, this review focuses on current knowledge regarding the genotoxicology of land snails. Classical biomarkers to assess genotoxic effects have been used (e.g., DNA breakage, micronuclei, random amplification polymorphic DNA) at various stages of the life cycle, including embryos. The studies were performed in vitro, in vivo, in situ and ex situ and covered a diverse set of contaminants (nanoparticles, metal(loid)s, pesticides, polycyclic aromatic hydrocarbons) and snail species (Cantareus aspersus, Eobania vermiculata, Theba pisana, Helix lucorum). Based on recent studies reviewed here, the use of land snails to map soil genotoxic potential is promising due to their ability to reveal pollution and subsequent environmental risks. Moreover, the position of snails in the trophic chain and the existing bridges between contaminant bioavailability to snails and bioaccessibility to humans reinforce the value of land snail-based ecotoxicological assessment.
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Affiliation(s)
- Maxime Louzon
- Ecosystem department, ENVISOL, 2 rue Hector Berlioz, 38110 La Tour du Pin, France
| | - Annette de Vaufleury
- UMR CNRS 6249 Chrono-Environnement, University of Franche-Comté, 16 route de Gray, 25030 Besançon Cedex, France
| | - Nicolas Capelli
- UMR CNRS 6249 Chrono-Environnement, University of Franche-Comté, 16 route de Gray, 25030 Besançon Cedex, France.
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2
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Hoff CA, Schmidt SS, Hackert BJ, Worley TK, Courcelle J, Courcelle CT. Events associated with DNA replication disruption are not observed in hydrogen peroxide-treated Escherichia coli. G3-GENES GENOMES GENETICS 2021; 11:6137848. [PMID: 33591320 PMCID: PMC8759817 DOI: 10.1093/g3journal/jkab044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/05/2021] [Indexed: 02/05/2023]
Abstract
UV irradiation induces pyrimidine dimers that block polymerases and disrupt the replisome. Restoring replication depends on the recF pathway proteins which process and maintain the replication fork DNA to allow the lesion to be repaired before replication resumes. Oxidative DNA lesions, such as those induced by hydrogen peroxide (H2O2), are often thought to require similar processing events, yet far less is known about how cells process oxidative damage during replication. Here we show that replication is not disrupted by H2O2-induced DNA damage in vivo. Following an initial inhibition, replication resumes in the absence of either lesion removal or RecF-processing. Restoring DNA synthesis depends on the presence of manganese in the medium, which we show is required for replication, but not repair to occur. The results demonstrate that replication is enzymatically inactivated, rather than physically disrupted by H2O2-induced DNA damage; indicate that inactivation is likely caused by oxidation of an iron-dependent replication or replication-associated protein that requires manganese to restore activity and synthesis; and address a long standing paradox as to why oxidative glycosylase mutants are defective in repair, yet not hypersensitive to H2O2. The oxygen-sensitive pausing may represent an adaptation that prevents replication from occurring under potentially lethal or mutagenic conditions.
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Affiliation(s)
- Chettar A Hoff
- Department of Biology, Portland State University, Portland, OR97201, USA
| | - Sierra S Schmidt
- Department of Biology, Portland State University, Portland, OR97201, USA
| | - Brandy J Hackert
- Department of Biology, Portland State University, Portland, OR97201, USA
| | - Travis K Worley
- Department of Biology, Portland State University, Portland, OR97201, USA
| | - Justin Courcelle
- Department of Biology, Portland State University, Portland, OR97201, USA
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3
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Mutation Spectrum Induced by 8-Bromoguanine, a Base Damaged by Reactive Brominating Species, in Human Cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:7308501. [PMID: 29098062 PMCID: PMC5643121 DOI: 10.1155/2017/7308501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/23/2017] [Accepted: 09/06/2017] [Indexed: 12/31/2022]
Abstract
To date, the types of mutations caused by 8-bromoguanine (8BrG), a major base lesion induced by reactive brominating species during inflammation, in human cells and the 8BrG repair system remain largely unknown. In this study, we performed a supF forward mutation assay using a shuttle vector plasmid containing a single 8BrG in three kinds of human cell lines and revealed that 8BrG in DNA predominantly induces a G → T mutation but can also induce G → C, G → A, and delG mutations in human cells. Next, we tested whether eight kinds of DNA glycosylases (MUTYH, MPG, NEIL1, OGG1, SMUG1, TDG, UNG2, and NTHL1) are capable of repairing 8BrG mispairs with any of the four bases using a DNA cleavage activity assay. We found that both the SMUG1 protein and the TDG protein exhibit DNA glycosylase activity against thymine mispaired with 8BrG and that the MUTYH protein exhibits DNA glycosylase activity against adenine mispaired with 8BrG. These results suggest that 8BrG induces some types of mutations, chiefly a G → T mutation, in human cells, and some DNA glycosylases are involved in the repair of 8BrG.
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4
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Markkanen E. Not breathing is not an option: How to deal with oxidative DNA damage. DNA Repair (Amst) 2017; 59:82-105. [PMID: 28963982 DOI: 10.1016/j.dnarep.2017.09.007] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 09/20/2017] [Indexed: 02/07/2023]
Abstract
Oxidative DNA damage constitutes a major threat to genetic integrity, and has thus been implicated in the pathogenesis of a wide variety of diseases, including cancer and neurodegeneration. 7,8-dihydro-8oxo-deoxyGuanine (8-oxo-G) is one of the best characterised oxidative DNA lesions, and it can give rise to point mutations due to its miscoding potential that instructs most DNA polymerases (Pols) to preferentially insert Adenine (A) opposite 8-oxo-G instead of the correct Cytosine (C). If uncorrected, A:8-oxo-G mispairs can give rise to C:G→A:T transversion mutations. Cells have evolved a variety of pathways to mitigate the mutational potential of 8-oxo-G that include i) mechanisms to avoid incorporation of oxidized nucleotides into DNA through nucleotide pool sanitisation enzymes (by MTH1, MTH2, MTH3 and NUDT5), ii) base excision repair (BER) of 8-oxo-G in DNA (involving MUTYH, OGG1, Pol λ, and other components of the BER machinery), and iii) faithful bypass of 8-oxo-G lesions during replication (using a switch between replicative Pols and Pol λ). In the following, the fate of 8-oxo-G in mammalian cells is reviewed in detail. The differential origins of 8-oxo-G in DNA and its consequences for genetic stability will be covered. This will be followed by a thorough discussion of the different mechanisms in place to cope with 8-oxo-G with an emphasis on Pol λ-mediated correct bypass of 8-oxo-G during MUTYH-initiated BER as well as replication across 8-oxo-G. Furthermore, the multitude of mechanisms in place to regulate key proteins involved in 8-oxo-G repair will be reviewed. Novel functions of 8-oxo-G as an epigenetic-like regulator and insights into the repair of 8-oxo-G within the cellular context will be touched upon. Finally, a discussion will outline the relevance of 8-oxo-G and the proteins involved in dealing with 8-oxo-G to human diseases with a special emphasis on cancer.
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Affiliation(s)
- Enni Markkanen
- Institute of Veterinary Pharmacology and Toxicology, Vetsuisse Faculty, University of Zürich, Winterthurerstr. 260, 8057 Zürich, Switzerland.
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5
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Kamiya H, Kurokawa M, Makino T, Kobayashi M, Matsuoka I. Induction of action-at-a-distance mutagenesis by 8-oxo-7,8-dihydroguanine in DNA pol λ-knockdown cells. Genes Environ 2015; 37:10. [PMID: 27350807 PMCID: PMC4918004 DOI: 10.1186/s41021-015-0015-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/09/2015] [Indexed: 11/13/2022] Open
Abstract
Introduction In DNA, 8-oxo-7,8-dihydroguanine (GO, 8-hydroxyguanine) is one of the most pivotal oxidatively damaged bases and induces G:C → T:A transversion mutations. DNA polymerase λ preferentially inserts dCTP opposite GOin vitro, and this error-free bypass function is considered to be important after A base removal from GO:A pairs by the MUTYH DNA glycosylase. To examine the effects of reduced levels of DNA polymerase λ on the GO-induced mutations, the polymerase was knocked-down in human U2OS cells, and a shuttle plasmid DNA containing a GO:C pair at position 122 in the supF gene was transfected into the cells. The plasmid DNA replicated in the cells was introduced into an Escherichia coli indicator strain, to measure the supF mutant frequency. Results The knockdown of DNA polymerase λ significantly enhanced the mutant frequency of the GO plasmid DNA. Contrary to our expectations, the knockdown did not promote the targeted G:C → T:A transversion. Instead, substitution mutations at G:C sites other than position 122 were enhanced in the cells. Conclusions These results suggested that the knockdown of DNA polymerase λ induced action-at-a-distance mutagenesis in human cells when the GO:C pair was present in the DNA.
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Affiliation(s)
- Hiroyuki Kamiya
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577 Japan ; Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 Japan ; College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, 790-8578 Japan
| | - Masahiro Kurokawa
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577 Japan
| | - Tetsuaki Makino
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577 Japan ; Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 Japan
| | - Miwako Kobayashi
- College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, 790-8578 Japan
| | - Ichiro Matsuoka
- College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, 790-8578 Japan
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Oxidatively induced DNA damage and its repair in cancer. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 763:212-45. [PMID: 25795122 DOI: 10.1016/j.mrrev.2014.11.002] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 12/28/2022]
Abstract
Oxidatively induced DNA damage is caused in living organisms by endogenous and exogenous reactive species. DNA lesions resulting from this type of damage are mutagenic and cytotoxic and, if not repaired, can cause genetic instability that may lead to disease processes including carcinogenesis. Living organisms possess DNA repair mechanisms that include a variety of pathways to repair multiple DNA lesions. Mutations and polymorphisms also occur in DNA repair genes adversely affecting DNA repair systems. Cancer tissues overexpress DNA repair proteins and thus develop greater DNA repair capacity than normal tissues. Increased DNA repair in tumors that removes DNA lesions before they become toxic is a major mechanism for development of resistance to therapy, affecting patient survival. Accumulated evidence suggests that DNA repair capacity may be a predictive biomarker for patient response to therapy. Thus, knowledge of DNA protein expressions in normal and cancerous tissues may help predict and guide development of treatments and yield the best therapeutic response. DNA repair proteins constitute targets for inhibitors to overcome the resistance of tumors to therapy. Inhibitors of DNA repair for combination therapy or as single agents for monotherapy may help selectively kill tumors, potentially leading to personalized therapy. Numerous inhibitors have been developed and are being tested in clinical trials. The efficacy of some inhibitors in therapy has been demonstrated in patients. Further development of inhibitors of DNA repair proteins is globally underway to help eradicate cancer.
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Xu L, Vaidyanathan VG, Cho BP. Real-time surface plasmon resonance study of biomolecular interactions between polymerase and bulky mutagenic DNA lesions. Chem Res Toxicol 2014; 27:1796-807. [PMID: 25195494 PMCID: PMC4203393 DOI: 10.1021/tx500252z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
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Surface plasmon resonance (SPR) was
used to measure polymerase-binding
interactions of the bulky mutagenic DNA lesions N-(2′-deoxyguanosin-8-yl)-4′-fluoro-4-aminobiphenyl
(FABP) or N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-acetylaminofluorene
(FAAF) in the context of two unique 5′-flanking bases (CG*A and TG*A). The enzymes used
were exo-nuclease-deficient Klenow fragment (Kf-exo–) or polymerase β (pol β). Specific binary and ternary
DNA binding affinities of the enzymes were characterized at subnanomolar
concentrations. The SPR results showed that Kf-exo– binds strongly to a double strand/single strand template/primer
junction, whereas pol β binds preferentially to double-stranded
DNA having a one-nucleotide gap. Both enzymes exhibited tight binding
to native DNA, with high nucleotide selectivity, where the KD values for each base pair increased in the
order dCTP ≪ dTTP ∼ dATP ≪ dGTP. In contrast
to that for pol β, Kf-exo– binds tightly to
lesion-modified templates; however, both polymerases exhibited minimal
nucleotide selectivity toward adducted DNA. Primer steady-state kinetics
and 19F NMR results support the SPR data. The relative
insertion efficiency fins of dCTP opposite
FABP was significantly higher in the TG*A sequence
compared to that in CG*A. Although Kf-exo– was not sensitive to the presence of a DNA lesion,
FAAF-induced conformational heterogeneity perturbed the active site
of pol β, weakening the enzyme’s ability to bind to FAAF
adducts compared to FABP adducts. The present study demonstrates the
effectiveness of SPR for elucidating how lesion-induced conformational
heterogeneity affects the binding capability of polymerases and ultimately
the nucleotide insertion efficiency.
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Affiliation(s)
- Lifang Xu
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
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8
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Koag MC, Min K, Lee S. Structural basis for promutagenicity of 8-halogenated guanine. J Biol Chem 2014; 289:6289-98. [PMID: 24425881 DOI: 10.1074/jbc.m113.537803] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
8-Halogenated guanine (haloG), a major DNA adduct formed by reactive halogen species during inflammation, is a promutagenic lesion that promotes misincorporation of G opposite the lesion by various DNA polymerases. Currently, the structural basis for such misincorporation is unknown. To gain insights into the mechanism of misincorporation across haloG by polymerase, we determined seven x-ray structures of human DNA polymerase β (polβ) bound to DNA bearing 8-bromoguanine (BrG). We determined two pre-catalytic ternary complex structures of polβ with an incoming nonhydrolyzable dGTP or dCTP analog paired with templating BrG. We also determined five binary complex structures of polβ in complex with DNA containing BrG·C/T at post-insertion and post-extension sites. In the BrG·dGTP ternary structure, BrG adopts syn conformation and forms Hoogsteen base pairing with the incoming dGTP analog. In the BrG·dCTP ternary structure, BrG adopts anti conformation and forms Watson-Crick base pairing with the incoming dCTP analog. In addition, our polβ binary post-extension structures show Hoogsteen BrG·G base pair and Watson-Crick BrG·C base pair. Taken together, the first structures of haloG-containing DNA bound to a protein indicate that both BrG·G and BrG·C base pairs are accommodated in the active site of polβ. Our structures suggest that Hoogsteen-type base pairing between G and C8-modified G could be accommodated in the active site of a DNA polymerase, promoting G to C mutation.
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Affiliation(s)
- Myong-Chul Koag
- From the Division of Medicinal Chemistry, College of Pharmacy, the University of Texas, Austin, Texas 78712
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9
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Vaidyanathan VG, Liang F, Beard WA, Shock DD, Wilson SH, Cho BP. Insights into the conformation of aminofluorene-deoxyguanine adduct in a DNA polymerase active site. J Biol Chem 2013; 288:23573-85. [PMID: 23798703 DOI: 10.1074/jbc.m113.476150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The active site conformation of the mutagenic fluoroaminofluorene-deoxyguanine adduct (dG-FAF, N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene) has been investigated in the presence of Klenow fragment of Escherichia coli DNA polymerase I (Kfexo(-)) and DNA polymerase β (pol β) using (19)F NMR, insertion assay, and surface plasmon resonance. In a single nucleotide gap, the dG-FAF adduct adopts both a major-groove- oriented and base-displaced stacked conformation, and this heterogeneity is retained upon binding pol β. The addition of a non-hydrolysable 2'-deoxycytosine-5'-[(α,β)-methyleno]triphosphate (dCMPcPP) nucleotide analog to the binary complex results in an increase of the major groove conformation of the adduct at the expense of the stacked conformation. Similar results were obtained with the addition of an incorrect dAMPcPP analog but with formation of the minor groove binding conformer. In contrast, dG-FAF adduct at the replication fork for the Kfexo(-) complex adopts a mix of the major and minor groove conformers with minimal effect upon the addition of non-hydrolysable nucleotides. For pol β, the insertion of dCTP was preferred opposite the dG-FAF adduct in a single nucleotide gap assay consistent with (19)F NMR data. Surface plasmon resonance binding kinetics revealed that pol β binds tightly with DNA in the presence of correct dCTP, but the adduct weakens binding with no nucleotide specificity. These results provide molecular insights into the DNA binding characteristics of FAF in the active site of DNA polymerases and the role of DNA structure and sequence on its coding potential.
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Affiliation(s)
- Vaidyanathan G Vaidyanathan
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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10
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Markkanen E, Dorn J, Hübscher U. MUTYH DNA glycosylase: the rationale for removing undamaged bases from the DNA. Front Genet 2013; 4:18. [PMID: 23450852 PMCID: PMC3584444 DOI: 10.3389/fgene.2013.00018] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 02/01/2013] [Indexed: 12/13/2022] Open
Abstract
Maintenance of genetic stability is crucial for all organisms in order to avoid the onset of deleterious diseases such as cancer. One of the many proveniences of DNA base damage in mammalian cells is oxidative stress, arising from a variety of endogenous and exogenous sources, generating highly mutagenic oxidative DNA lesions. One of the best characterized oxidative DNA lesion is 7,8-dihydro-8-oxoguanine (8-oxo-G), which can give rise to base substitution mutations (also known as point mutations). This mutagenicity is due to the miscoding potential of 8-oxo-G that instructs most DNA polymerases (pols) to preferentially insert an Adenine (A) opposite 8-oxo-G instead of the appropriate Cytosine (C). If left unrepaired, such A:8-oxo-G mispairs can give rise to CG→AT transversion mutations. A:8-oxo-G mispairs are proficiently recognized by the MutY glycosylase homologue (MUTYH). MUTYH can remove the mispaired A from an A:8-oxo-G, giving way to the canonical base-excision repair (BER) that ultimately restores undamaged Guanine (G). The importance of this MUTYH-initiated pathway is illustrated by the fact that biallelic mutations in the MUTYH gene are associated with a hereditary colorectal cancer syndrome termed MUTYH-associated polyposis (MAP). In this review, we will focus on MUTYH, from its discovery to the most recent data regarding its cellular roles and interaction partners. We discuss the involvement of the MUTYH protein in the A:8-oxo-G BER pathway acting together with pol λ, the pol that can faithfully incorporate C opposite 8-oxo-G and thus bypass this lesion in a correct manner. We also outline the current knowledge about the regulation of MUTYH itself and the A:8-oxo-G repair pathway by posttranslational modifications (PTM). Finally, to achieve a clearer overview of the literature, we will briefly touch on the rather confusing MUTYH nomenclature. In short, MUTYH is a unique DNA glycosylase that catalyzes the excision of an undamaged base from DNA.
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Affiliation(s)
- Enni Markkanen
- Institute for Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel Zürich, Switzerland
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11
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Chary P, Beard WA, Wilson SH, Lloyd RS. DNA polymerase β gap-filling translesion DNA synthesis. Chem Res Toxicol 2012; 25:2744-54. [PMID: 23121263 PMCID: PMC3523550 DOI: 10.1021/tx300368f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Although the primary function of DNA polymerase (pol)
β is
associated with gap-filling DNA synthesis as part of the DNA base
excision repair pathway, translesion synthesis activity has also been
described. To further understand the potential role of pol β-catalyzed
translesion DNA synthesis (TLS) and the structure–function
relationships of specific residues in pol β, wild-type and selected
mutants of pol β were used in TLS assays with DNA substrates
containing bulky polycyclic aromatic hydrocarbon-adducted oligonucleotides.
Stereospecific (+) and (−)-anti-trans-(C10S and C10R)
benzo[a]pyrene-7,8- dihydrodiol-9-10-epoxide (BPDE)
adducts were covalently attached to both the N6-adenine and N2-guanine in the major and minor grooves, respectively. For all substrates
tested, the presence of the BPDE adducts greatly decreased the efficiency
of nucleotide incorporation opposite the lesion, and the stereochemistry
of the adducts also further modulated the efficiency of the insertion
step, such that lesions which were oriented in the 3′ direction
relative to the approaching polymerase were considerably more blocking
than those oriented in the 5′ direction. In the absence of
a downstream DNA strand, the extension step beyond the adduct was
extremely inefficient, relative to a dinucleotide gap-filling reaction,
such that in the presence of the downstream DNA, dinucleotide incorporation
was strongly favored. In general, analyses of the TLS activities of
four pol β mutants revealed similar overall properties, but
wild-type pol β exhibited more than 50-fold greater extension
and bypass of the C10S-dA adducts as compared
to a low fidelity mutant R283K expected to interact with the templating
base. Replication bypass investigations were further extended to include
analyses of HIV-1 reverse transcriptase, and these studies revealed
patterns of inhibition very similar to that observed for pol β.
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Affiliation(s)
- Parvathi Chary
- Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239-3098, United States
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12
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Hamm ML, Crowley KA, Ghio M, Lindell MAM, McFadden EJ, Silberg JSL, Weaver AM. Biochemical Investigations into the Mutagenic Potential of 8-Oxo-2′-deoxyguanosine Using Nucleotide Analogues. Chem Res Toxicol 2012; 25:2577-88. [DOI: 10.1021/tx300365g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Michelle L. Hamm
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
| | - Kelly A. Crowley
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
| | - Michael Ghio
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
| | - Maria A. M. Lindell
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
| | - Emily J. McFadden
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
| | - Jordan S. L. Silberg
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
| | - Amelia M. Weaver
- Department
of Chemistry, University of Richmond, Gottwald B-100, Richmond, Virginia 23173,
United States
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13
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Kamiya H, Kurokawa M. Mutagenic bypass of 8-oxo-7,8-dihydroguanine (8-hydroxyguanine) by DNA polymerase κ in human cells. Chem Res Toxicol 2012; 25:1771-6. [PMID: 22804710 DOI: 10.1021/tx300259x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The formation of 8-oxo-7,8-dihydroguanine (G(O), 8-hydroxyguanine) in DNA and in the nucleotide pool results in G:C→T:A and A:T→C:G substitution mutations, respectively, since G(O) can pair with both C and A. In this study, the role of DNA polymerase κ in the mutagenicity of G(O) was investigated, using a supF shuttle plasmid propagated in human U2OS cells. This translesion synthesis DNA polymerase was knocked down by siRNA, and plasmid DNAs containing G(O):C and G(O):A pairs were transfected into the knock-down cells. The supF plasmid DNAs replicated in the cells were then introduced into Escherichia coli. Mutation analyses indicated that the knock-down of DNA polymerase κ by siRNA decreased the frequency of G:C→T:A mutation caused by G(O):C, although no effects of the DNA polymerase κ reduction were observed for the A:T→C:G substitution induced by G(O):A. These results suggested that DNA polymerase κ is involved in the mutagenic bypass of G(O) in living human cells, when the damaged base is generated by direct DNA oxidation.
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Affiliation(s)
- Hiroyuki Kamiya
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan.
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14
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15
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Schalow BJ, Courcelle CT, Courcelle J. Escherichia coli Fpg glycosylase is nonrendundant and required for the rapid global repair of oxidized purine and pyrimidine damage in vivo. J Mol Biol 2011; 410:183-93. [PMID: 21601577 DOI: 10.1016/j.jmb.2011.05.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 05/03/2011] [Accepted: 05/03/2011] [Indexed: 01/13/2023]
Abstract
Endonuclease (Endo) III and formamidopyrimidine-N-glycosylase (Fpg) are two of the predominant DNA glycosylases in Escherichia coli that remove oxidative base damage. In cell extracts and purified form, Endo III is generally more active toward oxidized pyrimidines, while Fpg is more active towards oxidized purines. However, the substrate specificities of these enzymes partially overlap in vitro. Less is known about the relative contribution of these enzymes in restoring the genomic template following oxidative damage. In this study, we examined how efficiently Endo III and Fpg repair their oxidative substrates in vivo following treatment with hydrogen peroxide. We found that Fpg was nonredundant and required to rapidly remove its substrate lesions on the chromosome. In addition, Fpg also repaired a significant portion of the lesions recognized by Endo III, suggesting that it plays a prominent role in the global repair of both purine damage and pyrimidine damage in vivo. By comparison, Endo III did not affect the repair rate of Fpg substrates and was only responsible for repairing a subset of its own substrate lesions in vivo. The absence of Endo VIII or nucleotide excision repair did not significantly affect the global repair of either Fpg or Endo III substrates in vivo. Surprisingly, replication recovered after oxidative DNA damage in all mutants examined, even when lesions persisted in the DNA, suggesting the presence of an efficient mechanism to process or overcome oxidative damage encountered during replication.
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Affiliation(s)
- Brandy J Schalow
- Department of Biology, Portland State University, PO Box 751, Portland, OR 97207, USA.
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16
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Sassa A, Ohta T, Nohmi T, Honma M, Yasui M. Mutational specificities of brominated DNA adducts catalyzed by human DNA polymerases. J Mol Biol 2011; 406:679-86. [PMID: 21241706 DOI: 10.1016/j.jmb.2011.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/24/2010] [Accepted: 01/04/2011] [Indexed: 11/29/2022]
Abstract
Chronic inflammation is known to lead to an increased risk for the development of cancer. Under inflammatory condition, cellular DNA is damaged by hypobromous acid, which is generated by myeloperoxidase and eosinophil peroxidase. The reactive brominating species induced brominated DNA adducts such as 8-bromo-2'-deoxyguanosine (8-Br-dG), 8-bromo-2'-deoxyadenosine (8-Br-dA), and 5-bromo-2'-deoxycytidine (5-Br-dC). These DNA lesions may be implicated in carcinogenesis. In this study, we analyzed the miscoding properties of the brominated DNA adducts generated by human DNA polymerases (pols). Site-specifically modified oligodeoxynucleotides containing a single 8-Br-dG, 8-Br-dA, or 5-Br-dC were used as a template in primer extension reactions catalyzed by human pols α, κ, and η. When 8-Br-dG-modified template was used, pol α primarily incorporated dCMP, the correct base, opposite the lesion, along with a small amount of one-base deletion (4.8%). Pol κ also promoted one-base deletion (14.2%), accompanied by misincorporation of dGMP (9.5%), dAMP (8.0%), and dTMP (6.1%) opposite the lesion. Pol η, on the other hand, readily bypassed the 8-Br-dG lesion in an error-free manner. As for 8-Br-dA and 5-Br-dC, all the pols bypassed the lesions and no miscoding events were observed. These results indicate that only 8-Br-dG, and not 5-Br-dC and 8-Br-dA, is a mutagenic lesion; the miscoding frequency and specificity vary depending on the DNA pol used. Thus, hypobromous acid-induced 8-Br-dG adduct may increase mutagenic potential at the site of inflammation.
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Affiliation(s)
- Akira Sassa
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Setagaya-ku, Tokyo 158-8501, Japan
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17
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Gieseking S, Bergen K, Di Pasquale F, Diederichs K, Welte W, Marx A. Human DNA polymerase beta mutations allowing efficient abasic site bypass. J Biol Chem 2010; 286:4011-20. [PMID: 21107011 DOI: 10.1074/jbc.m110.176826] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The DNA of every cell in the human body gets damaged more than 50,000 times a day. The most frequent damages are abasic sites. This kind of damage blocks proceeding DNA synthesis by several DNA polymerases that are involved in DNA replication and repair. The mechanistic basis for the incapability of these DNA polymerases to bypass abasic sites is not clarified. To gain insights into the mechanistic basis, we intended to identify amino acid residues that govern for the pausing of DNA polymerase β when incorporating a nucleotide opposite to abasic sites. Human DNA polymerase β was chosen because it is a well characterized DNA polymerase and serves as model enzyme for studies of DNA polymerase mechanisms. Moreover, it acts as the main gap-filling enzyme in base excision repair, and human tumor studies suggest a link between DNA polymerase β and cancer. In this study we employed high throughput screening of a library of more than 11,000 human DNA polymerase β variants. We identified two mutants that have increased ability to incorporate a nucleotide opposite to an abasic site. We found that the substitutions E232K and T233I promote incorporation opposite the lesion. In addition to this feature, the variants have an increased activity and a lower fidelity when processing nondamaged DNA. The mutations described in this work are located in well characterized regions but have not been reported before. A crystallographic structure of one of the mutants was obtained, providing structural insights.
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Affiliation(s)
- Sonja Gieseking
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78464 Konstanz, Germany
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18
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Dorjsuren D, Wilson DM, Beard WA, McDonald JP, Austin CP, Woodgate R, Wilson SH, Simeonov A. A real-time fluorescence method for enzymatic characterization of specialized human DNA polymerases. Nucleic Acids Res 2009; 37:e128. [PMID: 19684079 PMCID: PMC2770649 DOI: 10.1093/nar/gkp641] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Specialized DNA polymerases are involved in DNA synthesis during base-excision repair and translesion synthesis across a wide range of chemically modified DNA templates. Notable features of these enzymes include low catalytic efficiency, low processivity and low fidelity. Traditionally, in vitro studies of these enzymes have utilized radiolabeled substrates and gel electrophoretic separation of products. We have developed a simple homogeneous fluorescence-based method to study the enzymology of specialized DNA polymerases in real time. The method is based on fluorescent reporter strand displacement from a tripartite substrate containing a quencher-labeled template strand, an unlabeled primer and a fluorophore-labeled reporter. With this method, we could follow the activity of human DNA polymerases β, η, ι and κ under different reaction conditions, and we investigated incorporation of the aberrant nucleotide, 8-oxodGTP, as well as bypass of an abasic site or 8-oxoG DNA template lesion in different configurations. Lastly, we demonstrate that the method can be used for small molecule inhibitor discovery and characterization in highly miniaturized settings, and we report the first nanomolar inhibitors of Y-family DNA polymerases ι and η. The fluorogenic method presented here should facilitate mechanistic and inhibitor investigations of these polymerases and is also applicable to the study of highly processive replicative polymerases.
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Affiliation(s)
- Dorjbal Dorjsuren
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3370, USA
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19
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Donigan KA, Sweasy JB. Sequence context-specific mutagenesis and base excision repair. Mol Carcinog 2009; 48:362-8. [PMID: 19306280 DOI: 10.1002/mc.20497] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Base excision repair (BER) is critical for the maintenance of genome stability because it repairs at least 20,000 endogenously generated DNA lesions/cell/d. Several enzymes within the BER pathway exhibit sequence context dependency during the excision and DNA synthesis steps of repair. New evidence is emerging that germ line and tumor-associated variants of enzymes in this repair pathway exhibit sequence context dependence that is different from their ancestral counterparts. We review what is known about the ancestral and variant BER proteins within various sequence contexts. We suggest that altering the sequence context preferences of BER proteins could give rise to rare cellular variants that might have a selective advantage in response to environmental exposure or to the tumor microenvironment.
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Affiliation(s)
- Katherine A Donigan
- Departments of Therapeutic Radiology and Human Genetics, Yale University School of Medicine, 15 York Street, New Haven, CT 06520-8040, USA
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20
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Yung CW, Okugawa Y, Otsuka C, Okamoto K, Arimoto S, Loakes D, Negishi K, Negishi T. Influence of neighbouring base sequences on the mutagenesis induced by 7,8-dihydro-8-oxoguanine in yeast. Mutagenesis 2008; 23:509-13. [PMID: 18765421 DOI: 10.1093/mutage/gen044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have analysed the influence of neighbouring base sequences on the mutagenesis induced by 7,8-dihydro-8-oxoguanine (8-oxoG or G(o)), a typical oxidative lesion of DNA, using the yeast oligonucleotide transformation technique. Two oligonucleotides, oligo-CCG(o) and oligo-CGG(o), each possessing a single 8-oxoG residue and represented by the sequences 5'-CCG(o)-3' and 5'-CGG(o)-3', respectively, were introduced into a chromosome of Saccharomyces cerevisiae and their mutagenic potentials were compared. In a wild-type strain, 8-oxoG showed very weak mutagenic potential in both cases. However, the lesion in 5'-CCG(o)-3' can cause efficient G-to-T transversion in a strain lacking the rad30 gene which encodes yeast DNA polymerase eta (Ypoleta). To explore the properties associated with this translesion synthesis (TLS), the same two oligonucleotides possessing an 8-oxoG were used as templates for a standing-start primer extension assay, and the nucleotide incorporation opposite 8-oxoG was investigated. We found that dATP incorporation opposite 8-oxoG with Ypoleta was low for both sequences. In particular, very low dATP incorporation was observed for the 5'-CCG(o)-3' sequence. These results account for the efficient inhibition of mutagenesis by Ypoleta. TLS plays an important role in one DNA sequence in terms of avoiding mutagenesis induced by 8-oxoG in yeast. In contrast, human yeast DNA polymerase eta showed higher dATP incorporation rates even with the 5'-CCG(o)-3' sequence.
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Affiliation(s)
- Chin-Wei Yung
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Tsushima, Okayama 700-8530, Japan
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21
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Oliva J, Bardag-Gorce F, French BA, Li J, McPhaul L, Amidi F, Dedes J, Habibi A, Nguyen S, French SW. Fat10 is an epigenetic marker for liver preneoplasia in a drug-primed mouse model of tumorigenesis. Exp Mol Pathol 2008; 84:102-12. [PMID: 18280469 DOI: 10.1016/j.yexmp.2007.12.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
Abstract
There is clinical evidence that chronic liver diseases in which MDBs (Mallory Denk Bodies) form progress to hepatocellular carcinoma. The present study provides evidence that links MDB formation induced by chronic drug injury, with preneoplasia and later to the formation of tumors, which develop long after drug withdrawal. Evidence indicated that this link was due to an epigenetic cellular memory induced by chronic drug ingestion. Microarray analysis showed that the expressions of many markers of preneoplasia (UBD, Alpha Fetoprotein, KLF6 and glutathione-S-transferase mu2) were increased together when the drug DDC was refed. These changes were suppressed by S-adenosylmethionine feeding, indicating that the drug was affecting DNA and histones methylation in an epigenetic manner. The link between MDB formation and neoplasia formation was likely due to the over expression of UBD (also called FAT10), which is up regulated in 90% of human hepatocellular carcinomas. Immunohistochemical staining of drug-primed mouse livers showed that FAT10 positive liver cells persisted up to 4 months after drug withdrawal and they were still found in the livers of mice, 14 months after drug withdrawal. The refeeding of DDC increased the percent of FAT10 hepatocytes.
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Affiliation(s)
- Joan Oliva
- Department of Pathology, Harbor-UCLA Medical Center, 1000 W. Carson Street Torrance, CA 90509, USA
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22
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Jain R, Kumar P, Varshney U. A distinct role of formamidopyrimidine DNA glycosylase (MutM) in down-regulation of accumulation of G, C mutations and protection against oxidative stress in mycobacteria. DNA Repair (Amst) 2007; 6:1774-85. [PMID: 17698424 DOI: 10.1016/j.dnarep.2007.06.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2007] [Revised: 06/24/2007] [Accepted: 06/26/2007] [Indexed: 10/22/2022]
Abstract
Reactive oxygen species produced as a part of cellular metabolism or environmental agent cause a multitude of damages in cell. Oxidative damages to DNA or the free nucleotide pool result in occurrence of 7,8-dihydro-8-oxoguanine (8-oxoG) in DNA, and failure to replace it with the correct base results in a variety of mutations in the genome. Formamidopyrimidine DNA glycosylase (Fpg/MutM), a functionally conserved repair enzyme initiates the 8-oxoG repair pathway in all eubacteria. DNA in mycobacteria with G+C rich genomes is particularly vulnerable to the oxidative damage. In this study, we disrupted fpg gene in Mycobacterium smegmatis to generate an Fpg deficient strain. The strain showed an enhanced mutator phenotype and susceptibility to hydrogen peroxide. Analyses of rifampicin resistance determining region (RRDR) revealed that, in contrast to Fpg deficient Escherichia coli where C to A mutations predominate, Fpg deficient M. smegmatis shows a remarkable increase in accumulation of A to G (or T to C) mutations. Interestingly, exposure of the mutant to sub-lethal level of hydrogen peroxide results in a major shift towards C to G (or G to C) mutations. Biochemical analysis showed that mycobacterial Fpg; and MutY (which excises misincorporated A against 8-oxoG) possess substrate specificities similar to their counterparts in E. coli. However, the DNA polymerase assays with cell-free extracts showed preferential incorporation of G in M. smegmatis as opposed to an A in E. coli. Our studies highlight the importance and the distinctive features of Fpg mediated DNA repair in mycobacteria.
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Affiliation(s)
- Ruchi Jain
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
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23
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Upadhyay S, Chatterjee A, Trink B, Sommer M, Ratovitski E, Sidransky D. TAp63γ regulates hOGG1 and repair of oxidative damage in cancer cell lines. Biochem Biophys Res Commun 2007; 356:823-8. [PMID: 17399686 DOI: 10.1016/j.bbrc.2007.01.168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 01/29/2007] [Indexed: 11/20/2022]
Abstract
We showed that TAp63gamma regulates hOGG1. Using chromatin immunoprecipitation (ChIP), we found that TAp63gamma binds to the hOGG1 promoter. Reintroduction of wild-type TAp63gamma into HEK 293 cells, induced transcription of hOGG1 promoter, leading to increase in RNA and protein. Using RNAi studies, we observed that TAp63gamma-RNAi resulted in reduced hOGG1 RNA and protein in HeLa cells. This decrease in hOGG1 expression was associated with reduced cell viability upon oxidative damage. Taken together, our results indicate that hOGG1 is a direct target of TAp63gamma, suggesting a role for TAp63gamma in oxidative damage and repair.
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Affiliation(s)
- Sunil Upadhyay
- Department of Otolaryngology-Head and Neck Surgery, Head and Neck Cancer Research Division, The Johns Hopkins University School of Medicine, 1550 Orleans Street, 5N.03 Baltimore, MD 21231, USA
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24
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Kumar S, Lamarche BJ, Tsai MD. Use of damaged DNA and dNTP substrates by the error-prone DNA polymerase X from African swine fever virus. Biochemistry 2007; 46:3814-25. [PMID: 17335287 DOI: 10.1021/bi061501l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structural specificity that translesion DNA polymerases often show for a particular class of lesions suggests that the predominant criterion of selection during their evolution has been the capacity for lesion tolerance and that the error-proneness they display when copying undamaged templates may simply be a byproduct of this adaptation. Regardless of selection criteria/evolutionary history, at present both of these properties coexist in these enzymes, and both properties confer a fitness advantage. The repair polymerase, Pol X, encoded by the African swine fever virus (ASFV) is one of the most error-prone polymerases known, leading us to previously hypothesize that it may work in tandem with the exceptionally error-tolerant ASFV DNA ligase to effect viral mutagenesis. Here, for the first time, we test whether the error-proneness of Pol X is coupled with a capacity for lesion tolerance by examining its ability to utilize the types of damaged DNA and dNTP substrates that are expected to be relevant to ASFV. We (i) test Pol X's ability to both incorporate opposite to and extend from ubiquitous oxidative purine (7,8-dihydro-8-oxoguanine), oxidative pyrimidine (5,6-dihydroxy-5,6-dihydrothymine), and noncoding (AP site) lesions, in addition to 5,6-dihydrothymine, (ii) determine the catalytic efficiency and dNTP specificity of Pol X when catalyzing incorporation opposite to, and when extending from, 7,8-dihydro-8-oxoguanine in a template/primer context, and (iii) quantitate Pol X-catalyzed incorporation of the damaged nucleotide 8-oxo-dGTP opposite to undamaged templates in the context of both template/primer and a single-nucleotide gap. Our findings are discussed in light of ASFV biology and the mutagenic DNA repair hypothesis described above.
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Affiliation(s)
- Sandeep Kumar
- Department of Chemistry, The Biophysics Program, The Ohio State University, Columbus, Ohio 43210, USA
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25
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Barciszewski J, Massino F, Clark BFC. Kinetin--a multiactive molecule. Int J Biol Macromol 2007; 40:182-92. [PMID: 16899291 DOI: 10.1016/j.ijbiomac.2006.06.024] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 06/30/2006] [Accepted: 06/30/2006] [Indexed: 10/24/2022]
Abstract
Cytokinins are important adenine derivatives that serve as hormones to control many processes in plants. They were discovered as factors that promote cell division in tobacco tissue cultures and have been shown also to regulate several other developmental events. Kinetin which was isolated 50 years ago for the first time as a plant hormone, as well as other cytokinins isopentenyladenine, zeatin and benzylaminopurine induce callus (clusters of dedifferentiated plant cells) to redifferentiate into adventitious buds. Because of some similarities in the biological phenotypes of cancer and callus cells, cytokinins and especially kinetin, affect the differentiation of human cells through a common signal transduction system. Therefore, cytokinins found their way to use in molecular medicine.
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Affiliation(s)
- Jan Barciszewski
- Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Noskowskiego 12, 61-704 Poznan, Poland.
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26
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McCulloch SD, Kunkel TA. Multiple solutions to inefficient lesion bypass by T7 DNA polymerase. DNA Repair (Amst) 2006; 5:1373-83. [PMID: 16876489 PMCID: PMC1892196 DOI: 10.1016/j.dnarep.2006.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 06/08/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022]
Abstract
We hypothesize that enzymatic switching during translesion synthesis (TLS) to relieve stalled replication forks occurs during transitions from preferential to disfavored use of damaged primer-templates, and that the polymerase or 3'-exonuclease used for each successive nucleotide incorporated is the one whose properties result in the highest efficiency and the highest fidelity of bypass. Testing this hypothesis requires quantitative determination of the relative lesion bypass ability of both TLS polymerases and major replicative polymerases. As a model of the latter, here we measure the efficiency and fidelity of cis-syn TT dimer and abasic site bypass using the structurally well-characterized T7 DNA polymerase. No bypass of either lesion occurred during a single round of synthesis, and the exonuclease activity of wild-type T7 DNA polymerase was critical in preventing TLS. When repetitive cycling of the exonuclease-deficient enzyme was allowed, limited bypass did occur but hundreds to thousands of cycles were required to achieve even a single bypass event. Analysis of TLS fidelity indicated that these rare bypass events involved rearrangements of the template and primer strands, insertions opposite the lesion, and combinations of these events, with the choice among these strongly depending on the sequence context of the lesion. Moreover, the presence of a lesion affected the fidelity of copying adjacent undamaged template bases, even when lesion bypass itself was correct. The results also indicate that a TT dimer presents a different type of block to the polymerase than an abasic site, even though both lesions are extremely potent blocks to processive synthesis. The approaches used here to quantify the efficiency and fidelity of TLS can be applied to other polymerase-lesion combinations, to provide guidance as to which of many possible polymerases is most likely to bypass various lesions in biological contexts.
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Affiliation(s)
- Scott D. McCulloch
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
| | - Thomas A. Kunkel
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
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Durant ST, Paffett KS, Shrivastav M, Timmins GS, Morgan WF, Nickoloff JA. UV radiation induces delayed hyperrecombination associated with hypermutation in human cells. Mol Cell Biol 2006; 26:6047-55. [PMID: 16880516 PMCID: PMC1592811 DOI: 10.1128/mcb.00444-06] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ionizing radiation induces delayed genomic instability in human cells, including chromosomal abnormalities and hyperrecombination. Here, we investigate delayed genome instability of cells exposed to UV radiation. We examined homologous recombination-mediated reactivation of a green fluorescent protein (GFP) gene in p53-proficient human cells. We observed an approximately 5-fold enhancement of delayed hyperrecombination (DHR) among cells surviving a low dose of UV-C (5 J/m2), revealed as mixed GFP+/- colonies. UV-B did not induce DHR at an equitoxic (75 J/m2) dose or a higher dose (150 J/m2). UV is known to induce delayed hypermutation associated with increased oxidative stress. We found that hypoxanthine phosphoribosyltransferase (HPRT) mutation frequencies were approximately 5-fold higher in strains derived from GFP+/- (DHR) colonies than in strains in which recombination was directly induced by UV (GFP+ colonies). To determine whether hypermutation was directly caused by hyperrecombination, we analyzed hprt mutation spectra. Large-scale alterations reflecting large deletions and insertions were observed in 25% of GFP+ strains, and most mutants had a single change in HPRT. In striking contrast, all mutations arising in the hypermutable GFP+/- strains were small (1- to 2-base) changes, including substitutions, deletions, and insertions (reminiscent of mutagenesis from oxidative damage), and the majority were compound, with an average of four hprt mutations per mutant. The absence of large hprt deletions in DHR strains indicates that DHR does not cause hypermutation. We propose that UV-induced DHR and hypermutation result from a common source, namely, increased oxidative stress. These two forms of delayed genome instability may collaborate in skin cancer initiation and progression.
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Affiliation(s)
- Stephen T Durant
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
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28
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Ohno M, Miura T, Furuichi M, Tominaga Y, Tsuchimoto D, Sakumi K, Nakabeppu Y. A genome-wide distribution of 8-oxoguanine correlates with the preferred regions for recombination and single nucleotide polymorphism in the human genome. Genome Res 2006; 16:567-75. [PMID: 16651663 PMCID: PMC1457041 DOI: 10.1101/gr.4769606] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
8-Oxoguanine (8-oxoG), a major spontaneous form of oxidative DNA damage, is considered to be a natural cause of genomic diversity in organisms because of its mutagenic potential. The steady-state level of 8-oxoG in the nuclear genome of a human cell has been estimated to be several residues per 10(6) guanines. In the present study, to clarify the genome-wide distribution of 8-oxoG in the steady state, we performed fluorescence in situ detection of 8-oxoG on human metaphase chromosomes using a monoclonal antibody. Multiple dot-like signals were observed on each metaphase chromosome. We then mapped the position of the signal at megabase resolution referring to the cytogenetically identified chromosomal band, and demonstrated that 8-oxoG is unevenly distributed in the normal human genome and that the distribution pattern is conserved among different individuals. Moreover, we found that regions with a high frequency of recombination and single nucleotide polymorphisms (SNPs) are preferentially located within chromosomal regions with a high density of 8-oxoG. Our findings suggest that 8-oxoG is one of the main causes of frequent recombinations and SNPs in the human genome, which largely contribute to the genomic diversity in human beings.
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Affiliation(s)
- Mizuki Ohno
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
| | - Tomofumi Miura
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
- Department of Neuropsychiatry, Graduate School of Medical Sciences
| | - Masato Furuichi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
- Radioisotope Center, Kyushu University, Fukuoka 812-8582, Japan
| | - Yohei Tominaga
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
| | - Daisuke Tsuchimoto
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
| | - Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation
- Corresponding author.E-mail ; fax +81-92-642-6791
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29
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Kalam MA, Haraguchi K, Chandani S, Loechler EL, Moriya M, Greenberg MM, Basu AK. Genetic effects of oxidative DNA damages: comparative mutagenesis of the imidazole ring-opened formamidopyrimidines (Fapy lesions) and 8-oxo-purines in simian kidney cells. Nucleic Acids Res 2006; 34:2305-15. [PMID: 16679449 PMCID: PMC1458282 DOI: 10.1093/nar/gkl099] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Fapy.dG and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) are formed in DNA by hydroxyl radical damage. In order to study replication past these lesions in cells, we constructed a single-stranded shuttle vector containing the lesion in 5'-TGT and 5'-TGA sequence contexts. Replication of the modified vector in simian kidney (COS-7) cells showed that Fapy.dG is mutagenic inducing primarily targeted Fapy.G-->T transversions. In the 5'-TGT sequence mutational frequency of Fapy.dG was approximately 30%, whereas in the 5'-TGA sequence it was approximately 8%. In parallel studies 8-oxo-dG was found to be slightly less mutagenic than Fapy.dG, though it also exhibited a similar context effect: 4-fold G-->T transversions (24% versus 6%) occurred in the 5'-TGT sequence relative to 5'-TGA. To investigate a possible structural basis for the higher G-->T mutations induced by both lesions when their 3' neighbor was T, we carried out a molecular modeling investigation in the active site of DNA polymerase beta, which is known to incorporate both dCTP (no mutation) and dATP (G-->T substitution) opposite 8-oxo-G. In pol beta, the syn-8-oxo-G:dATP pair showed greater stacking with the 3'-T:A base pair in the 5'-TGT sequence compared with the 3'-A:T in the 5'-TGA sequence, whereas stacking for the anti-8-oxo-G:dCTP pair was similar in both 5'-TGT and 5'-TGA sequences. Similarly, syn-Fapy.G:dATP pairing showed greater stacking in the 5'-TGT sequence compared with the 5'-TGA sequence, while stacking for anti-Fapy.G:dCTP pairs was similar in the two sequences. Thus, for both lesions less efficient base stacking between the lesion:dATP pair and the 3'-A:T base pair in the 5'-TGA sequence might cause lower G-->T mutational frequencies in the 5'-TGA sequence compared to 5'-TGT. The corresponding lesions derived from 2'-deoxyadenosine, Fapy.dA and 8-oxo-dA, were not detectably mutagenic in the 5'-TAT sequence, and were only weakly mutagenic (<1%) in the 5'-TAA sequence context, where both lesions induced targeted A-->C transversions. To our knowledge this is the first investigation using extrachromosomal probes containing a Fapy.dG or Fapy.dA site-specifically incorporated, which showed unequivocally that in simian kidney cells Fapy.G-->T substitutions occur at a higher frequency than 8-oxo-G-->T and that Fapy.dA is very weakly mutagenic, as is 8-oxo-dA.
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Affiliation(s)
| | - Kazuhiro Haraguchi
- Department of Chemistry, Johns Hopkins UniversityBaltimore, MD 21218, USA
| | | | | | - Maasaki Moriya
- Department of Pharmacological Sciences, State University of New YorkStony Brook, NY 11794, USA
| | - Marc M. Greenberg
- Department of Chemistry, Johns Hopkins UniversityBaltimore, MD 21218, USA
| | - Ashis K. Basu
- To whom correspondence should be addressed. Tel: +1 860 486 3965; Fax: +1 860 486 2981;
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30
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
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31
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Affiliation(s)
- William A Beard
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709-12233, USA
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Rechkoblit O, Malinina L, Cheng Y, Kuryavyi V, Broyde S, Geacintov NE, Patel DJ. Stepwise translocation of Dpo4 polymerase during error-free bypass of an oxoG lesion. PLoS Biol 2006; 4:e11. [PMID: 16379496 PMCID: PMC1325099 DOI: 10.1371/journal.pbio.0040011] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Accepted: 11/01/2005] [Indexed: 12/02/2022] Open
Abstract
7,8-dihydro-8-oxoguanine (oxoG), the predominant lesion formed following oxidative damage of DNA by reactive oxygen species, is processed differently by replicative and bypass polymerases. Our kinetic primer extension studies demonstrate that the bypass polymerase Dpo4 preferentially inserts C opposite oxoG, and also preferentially extends from the oxoG•C base pair, thus achieving error-free bypass of this lesion. We have determined the crystal structures of preinsertion binary, insertion ternary, and postinsertion binary complexes of oxoG-modified template-primer DNA and Dpo4. These structures provide insights into the translocation mechanics of the bypass polymerase during a complete cycle of nucleotide incorporation. Specifically, during noncovalent dCTP insertion opposite oxoG (or G), the little-finger domain–DNA phosphate contacts translocate by one nucleotide step, while the thumb domain–DNA phosphate contacts remain fixed. By contrast, during the nucleotidyl transfer reaction that covalently incorporates C opposite oxoG, the thumb-domain–phosphate contacts are translocated by one nucleotide step, while the little-finger contacts with phosphate groups remain fixed. These stepwise conformational transitions accompanying nucleoside triphosphate binding and covalent nucleobase incorporation during a full replication cycle of Dpo4-catalyzed bypass of the oxoG lesion are distinct from the translocation events in replicative polymerases. Crystal structures of the bypass polymerase Dpo4 at different stages of lesion-bypass reveal how the cell copes with oxidative DNA damage.
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Affiliation(s)
- Olga Rechkoblit
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Lucy Malinina
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Yuan Cheng
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Vitaly Kuryavyi
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Suse Broyde
- 2Biology Department, New York University, New York, New York, United States of America
| | - Nicholas E Geacintov
- 3Chemistry Department, New York University, New York, New York, United States of America
| | - Dinshaw J Patel
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
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Zang H, Harris TM, Guengerich FP. Kinetics of nucleotide incorporation opposite polycyclic aromatic hydrocarbon-DNA adducts by processive bacteriophage T7 DNA polymerase. Chem Res Toxicol 2005; 18:389-400. [PMID: 15720147 DOI: 10.1021/tx049683c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of six oligonucleotides with dihydrodiol epoxide metabolites of the polycyclic aromatic hydrocarbons (PAHs) benz[a]anthracene and benzo[a]pyrene attached to adenine N6 and guanine N2 atoms were prepared and studied with the processive bacteriophage DNA polymerase T7, exonuclease- (T7-). HIV-1 reverse transcriptase was much less efficient in polymerization than T7-. Benz[a]anthracene and benzo[a]pyrene adducts strongly blocked incorporation of dTTP and dCTP opposite the A and G derivatives, respectively. dATP was preferentially incorporated in all cases. Steady state kinetic analysis indicated that the low catalytic efficiency with adducted DNA was due to both increased K(m) and lowered k(cat) values. Some differences due to PAH stereochemistry were observed. Fluorescence estimates of K(d) and presteady state kinetic measurements of k(off) showed no major decrease in the affinity of T7- with damaged DNA substrates or with dNTPs. Presteady state kinetics showed a lack of the normal burst kinetics for dNTP incorporation with all PAH-DNA derivatives. These results indicate that the rate-limiting step is at or before the step of phosphodiester bond formation; release of the oligonucleotide is no longer the slowest step. Thio elemental effects (substitution of alpha-oxygen with sulfur) were relatively small, in contrast to previous work with T7- and 8-oxo-7,8-dihydroguanine. The effect of these bulky PAH adducts is either to attenuate rates of conformational changes or to introduce an additional conformation problem but not to alter the inherent affinity of the polymerase for DNA or dNTPs.
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Affiliation(s)
- Hong Zang
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
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Luo H, Tang L, Tang M, Billam M, Huang T, Yu J, Wei Z, Liang Y, Wang K, Zhang ZQ, Zhang L, Wang JS. Phase IIa chemoprevention trial of green tea polyphenols in high-risk individuals of liver cancer: modulation of urinary excretion of green tea polyphenols and 8-hydroxydeoxyguanosine. Carcinogenesis 2005; 27:262-8. [PMID: 15930028 DOI: 10.1093/carcin/bgi147] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Modulation of urinary excretion of green tea polyphenols (GTPs) and oxidative DNA damage biomarker, 8-hydroxydeoxyguanosine (8-OHdG), were assessed in urine samples collected from a randomized, double-blinded and placebo-controlled phase IIa chemoprevention trial with GTP in 124 individuals. These individuals were sero-positive for both HBsAg and aflatoxin-albumin adducts, and took GTP capsules daily at doses of 500 mg, 1000 mg or a placebo for 3 months. Twenty-four hour urine samples were collected before the intervention and at the first and third month of the study. Urinary excretion of 8-OHdG and GTP components was measured by HPLC-CoulArray electrochemical detection. The baseline levels of 8-OHdG and GTP components among the three groups showed homogeneity (P > 0.70), and a non-significant fluctuation was observed in the placebo group over the 3 months (P > 0.30). In GTP-treated groups, epigallocatechin (EGC) and epicatechin (EC) levels displayed significant and dose-dependent increases in both the 500 mg group and 1000 mg group (P < 0.05). The 8-OHdG levels did not differ between the three groups at the 1 month collection, with medians of 1.83, 2.08 and 1.86 ng/mg-creatinine for placebo, 500 and 1000 mg group, respectively (P = 0.999). At the end of the 3 months' intervention, 8-OHdG levels decreased significantly in both GTP-treated groups, with medians of 2.02, 1.03 and 1.15 ng/mg-creatinine for placebo, 500 mg and 1000 mg group, respectively (P = 0.007). These results suggest that urinary excretions of EGC and EC can serve as practical biomarkers for green tea consumption in human populations. The results also suggest that chemoprevention with GTP is effective in diminishing oxidative DNA damage.
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Affiliation(s)
- Haitao Luo
- The Institute of Environmental and Human Health and Department of Environmental Toxicology, Texas Tech University, PO Box 41163, Lubbock, TX 79409-1163, USA
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Jałoszyński P, Ohashi E, Ohmori H, Nishimura S. Error-prone and inefficient replication across 8-hydroxyguanine (8-oxoguanine) in human and mouse ras gene fragments by DNA polymerase κ. Genes Cells 2005; 10:543-50. [PMID: 15938713 DOI: 10.1111/j.1365-2443.2005.00858.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using fragments of human c-Ha-ras and mouse Ha-ras1 genes containing 8-hydroxyguanine (8-OH-G) in hypermutagenic codon 12, we analyzed the kinetics of DNA synthesis catalyzed by human Polkappa. This translesion DNA polymerase, belonging to the Y-family, was found to be moderately inhibited by the presence of 8-OH-G on either mouse or human templates. From our previous results, inhibition of various polymerases by 8-OH-G increases in the following order: Poleta < Polkappa < Polbeta < Polalpha, showing that major replicative and repair polymerases are more sensitive to this lesion than enzymes belonging to the Y-family. In the direct mutagenesis experiments, Polkappa was found to be more mutagenic than Poleta studied previously: it inserted dAMP more efficiently than dCMP opposite 8-OH-G. Polkappa was also able to cause indirect mispair ('action-at-a-distance' mutagenesis), this effect being more distinct on mouse templates. Two adjacent 8-OH-G residues in codon 12 inhibited Polkappa moderately and induced misincorporation of dAMP. However, this effect was not comparable to the strong relaxation of the enzyme specificity, observed previously in the case of Poleta. Polkappa catalyzed incorporation (and misincorporation of dAMP) much more efficiently on mouse templates, human DNA fragments being distinctly worse substrates. Interestingly, in direct mutagenesis systems, the preference for dAMP over dCMP was nearly the same on mouse and human templates.
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Affiliation(s)
- Paweł Jałoszyński
- Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd, Okubo 3, Tsukuba, Ibaraki 300-2611, Japan.
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36
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David O, Bourré L, Krika Y, Durand M, Patrice T. DNA damages after SIM01 photodynamic treatment. Photodiagnosis Photodyn Ther 2005; 2:25-33. [DOI: 10.1016/s1572-1000(05)00011-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 01/21/2005] [Accepted: 02/16/2005] [Indexed: 10/25/2022]
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37
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Seike K, Murata M, Oikawa S, Hiraku Y, Hirakawa K, Kawanishi S. Oxidative DNA damage induced by benz[a]anthracene metabolites via redox cycles of quinone and unique non-quinone. Chem Res Toxicol 2005; 16:1470-6. [PMID: 14615974 DOI: 10.1021/tx034103h] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Benz[a]anthracene (BA) is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) that are ubiquitous environmental pollutants. PAH carcinogenesis is explained by DNA adduct formation by PAH diol epoxide and oxidative DNA damage by PAH o-quinone. Benz[a]anthracene-trans-3,4-dihydrodiol (BA-3,4-dihydrodiol) is a minor metabolite but shows higher mutagenicity and tumorigenicity than parent BA. We confirmed that a BA o-quinone type metabolite, benz[a]anthracene-3,4-dione (BA-3,4-dione), induced oxidative DNA damage in the presence of cytochrome P450 reductase. Interestingly, we found that BA-3,4-dihydrodiol nonenzymatically caused Cu(II)-mediated DNA damage including 8-oxo-7,8-dihydro-2'-deoxyguanosine formation and the addition of NADH enhanced DNA damage. BA-3,4-dihydrodiol induced a double-base lesion of C and G at the 5'-ACG-3' sequence complementary to codon 273 of the human p53 tumor suppressor gene, which is known as a hotspot. The DNA damage was inhibited by catalase and bathocuproine, indicating the involvement of H(2)O(2) and Cu(I). Time-of-flight mass spectroscopic study suggested that BA-3,4-dihydrodiol undergoes Cu(II)-mediated autoxidation leading to the formation of its hydroxylated form of BA-3,4-dihydrodiol, capable of causing oxidative DNA damage. It is noteworthy that BA-3,4-dihydrodiol can nonenzymatically induce DNA damage more efficiently than BA-3,4-dione with metabolic activation. In conclusion, oxidative DNA damage induced by BA-3,4-dihydrodiol not only via quinone-type redox cycle but also via a new type of redox cycle participates in the expression of carcinogenicity of BA and BA-3,4-dihydrodiol.
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Affiliation(s)
- Kazuharu Seike
- Department of Environmental and Molecular Medicine, Mie University School of Medicine, Tsu, Mie 514-8507, Japan
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38
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Lim P, Wuenschell GE, Holland V, Lee DH, Pfeifer GP, Rodriguez H, Termini J. Peroxyl radical mediated oxidative DNA base damage: implications for lipid peroxidation induced mutagenesis. Biochemistry 2005; 43:15339-48. [PMID: 15581346 DOI: 10.1021/bi048276x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Endogenous DNA damage induced by lipid peroxidation is believed to play a critical role in carcinogenesis. Lipid peroxidation generates free radical intermediates (primarily peroxyl radicals, ROO(*)) and electrophilic aldehydes as the principal genotoxicants. Although detailed information is available on the role of aldehyde base adducts in mutagenesis and carcinogenesis, the contribution of peroxyl radical mediated DNA base damage is less well understood. In the present study we have mapped oxidative base damage induced by peroxyl radicals in the supF tRNA gene and correlated this information with peroxidation-induced mutations in several human fibroblast cell lines. Nearly identical patterns of oxidative base damage were obtained from reaction of DNA with either peroxidizing arachidonic acid (20:4omega6) or peroxyl radicals generated by thermolysis of ABIP in the presence of oxygen. Oxidative base damage primarily occurred at G and C. Transversions at GC base pairs in the supF gene were the major base substitution detected in all cell lines. Peroxyl radical induced tandem mutations were also observed. Many mutation hot spots coincided with sites of mapped oxidative lesions, although in some cases hot spots occurred adjacent to the damaged base. Evidence is presented for the involvement of 8-oxodG in the oxidation of DNA by ROO(*). These results are used to interpret some key features of previously published mutation spectra induced by lipid peroxidation in human cells.
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Affiliation(s)
- Punnajit Lim
- Division of Molecular Biology and Biology, Beckman Research Institute of the City of Hope, 1450 East Duarte Road, Duarte, California 91010, USA
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Besaratinia A, Bates SE, Synold TW, Pfeifer GP. Similar mutagenicity of photoactivated porphyrins and ultraviolet A radiation in mouse embryonic fibroblasts: involvement of oxidative DNA lesions in mutagenesis. Biochemistry 2005; 43:15557-66. [PMID: 15581368 DOI: 10.1021/bi048717c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ultraviolet A (UVA) radiation is implicated in the etiology of human skin cancer. However, the underlying mechanism of carcinogenicity for UVA is not fully delineated. A mutagenic role for UVA has been suggested, which involves activation of endogenous photosensitizers generating oxidative DNA damage. We investigated the mutagenicity of UVA alone and in combination with delta-aminolevulinic acid (delta-ALA), a precursor of the intracellular photosensitizers porphyrins, in transgenic Big Blue mouse embryonic fibroblasts. A significant generation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a typical promutagenic oxidative DNA lesion, was observed in cells treated with a combination of delta-ALA (1 mM) and UVA (0.06 J/cm(2)) as quantified by high-pressure liquid chromatography-tandem mass spectrometry (p < 0.001; relative to the control). The steady-state level of 8-oxo-dG, however, remained unchanged in cells irradiated with UVA or treated with delta-ALA alone. Other photolesions including cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts were not detectable in cells treated with delta-ALA and/or irradiated with UVA as determined by terminal transferase-dependent polymerase chain reaction assay. Mutation analyses of the cII transgene in cells treated with a combination of delta-ALA and UVA showed an approximately 3-fold increase in mutant frequency relative to the control (p < 0.008), as well as a unique induced mutation spectrum as established by DNA sequence analysis (p < 0.005; 95% CI, 0.002-0.009). No mutagenic effects were observed in cells irradiated with UVA or treated with delta-ALA alone. The spectrum of mutations produced by delta-ALA plus UVA was characterized by a significantly increased frequency of G --> T transversions (p < 0.0003; relative to the control), which are the hallmark mutations induced by 8-oxo-dG. Notably, the 8-oxo-dG-mediated mutagenicity of UVA plus delta-ALA is similar to that established previously for UVA alone at a mutagenic dose of 18 J/cm(2). We conclude that, in the presence of exogenous photosensitizers, UVA at a nonmutagenic dose induces mutations through the same mechanism as does a mutagenic dose of UVA per se.
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Affiliation(s)
- Ahmad Besaratinia
- Division of Biology and Department of Medical Oncology, Beckman Research Institute of the City of Hope National Medical Center, 1450 East Duarte Road, Duarte, California 91010, USA.
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Evans MD, Dizdaroglu M, Cooke MS. Oxidative DNA damage and disease: induction, repair and significance. MUTATION RESEARCH/REVIEWS IN MUTATION RESEARCH 2004; 567:1-61. [PMID: 15341901 DOI: 10.1016/j.mrrev.2003.11.001] [Citation(s) in RCA: 878] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Revised: 11/12/2003] [Accepted: 11/12/2003] [Indexed: 04/08/2023]
Abstract
The generation of reactive oxygen species may be both beneficial to cells, performing a function in inter- and intracellular signalling, and detrimental, modifying cellular biomolecules, accumulation of which has been associated with numerous diseases. Of the molecules subject to oxidative modification, DNA has received the greatest attention, with biomarkers of exposure and effect closest to validation. Despite nearly a quarter of a century of study, and a large number of base- and sugar-derived DNA lesions having been identified, the majority of studies have focussed upon the guanine modification, 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-OH-dG). For the most part, the biological significance of other lesions has not, as yet, been investigated. In contrast, the description and characterisation of enzyme systems responsible for repairing oxidative DNA base damage is growing rapidly, being the subject of intense study. However, there remain notable gaps in our knowledge of which repair proteins remove which lesions, plus, as more lesions identified, new processes/substrates need to be determined. There are many reports describing elevated levels of oxidatively modified DNA lesions, in various biological matrices, in a plethora of diseases; however, for the majority of these the association could merely be coincidental, and more detailed studies are required. Nevertheless, even based simply upon reports of studies investigating the potential role of 8-OH-dG in disease, the weight of evidence strongly suggests a link between such damage and the pathogenesis of disease. However, exact roles remain to be elucidated.
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Affiliation(s)
- Mark D Evans
- Oxidative Stress Group, Department of Clinical Biochemistry, University of Leicester, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, LE2 7LX, UK
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Jałoszyński P, Masutani C, Hanaoka F, Perez AB, Nishimura S. 8-Hydroxyguanine in a mutational hotspot of the c-Ha-ras gene causes misreplication, 'action-at-a-distance' mutagenesis and inhibition of replication. Nucleic Acids Res 2003; 31:6085-95. [PMID: 14576295 PMCID: PMC275471 DOI: 10.1093/nar/gkg829] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Revised: 09/11/2003] [Accepted: 09/11/2003] [Indexed: 11/14/2022] Open
Abstract
Mutations in particular codons of c-Ha-ras have a strong activating potential, and an activated ras oncogene has been found in a number of human cancers. Using fragments of the human c-Ha-ras gene containing 8-hydroxyguanine (8-OH-G) in codon 12, we provide evidence for highly complex biochemical events leading to activation of the oncogene. Replication with DNA polymerases alpha (Pol(alpha)) and beta (Pol(beta)) led to misincorporation of dAMP, while DNA polymerase eta (Pol(eta)) caused additional insertion of dGMP. For the first time we report an 'action-at-a-distance' mutagenic effect for Pol(eta). Replication catalyzed by this enzyme resulted in misincorporating dAMP, dTMP and dGMP opposite non-oxidized guanine 3'-flanked by 8-OH-G. Interestingly, two adjacent 8-OH-G residues greatly relaxed the specificity of Pol(eta), which in this system was able to incorporate all four nucleotides. Moreover, two adjacent 8-OH-G residues completely blocked Pol(alpha) and strongly inhibited Pol(beta), whereas Pol(eta) was entirely resistant to this inhibition. These results suggest an important role for Pol(eta) in inducing hypermutability in codon 12. Our observations are important for understanding the consequences of 8-OH-G being positioned within the mutational hot spots of oncogenes, the outcome of which appears to be relatively complex even in minimal in vitro systems.
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Affiliation(s)
- Paweł Jałoszyński
- Banyu Tsukuba Research Institute in Collaboration with Merck Research Laboratories, Okubo 3, Tsukuba, Ibaraki 300-2611, Japan
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Fowler RG, White SJ, Koyama C, Moore SC, Dunn RL, Schaaper RM. Interactions among the Escherichia coli mutT, mutM, and mutY damage prevention pathways. DNA Repair (Amst) 2003; 2:159-73. [PMID: 12531387 DOI: 10.1016/s1568-7864(02)00193-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated in detail the interactions between the Escherichia coli mutT, mutM, and mutY error-prevention systems. Jointly, these systems protect the cell against the effects of the oxidative stress product, 8-oxoguanine (8-oxoG), a base analog with ambiguous base-pairing properties, pairing with either A or C during DNA synthesis. mutT mutator strains display a specific increase in A.T-->C.G transversions, while mutM and mutY mutator strains show specific G.C-->T.A increases. To study in more detail the in vivo processing of the various mutational intermediates leading to A.T-->C.G and G.C-->T.A transversions, we analyzed defined A.T-->C.G and G.C-->T.A events in strains containing all possible combinations of these mutator alleles. We report three major findings. First, we do not find evidence that the mutT allele significantly increases G.C-->T.A transversions in either mut(+), mutM, mutY or mutMmutY backgrounds. We interpret this result to indicate that incorporation of 8-oxodGTP opposite template C may not be frequent relative to incorporation opposite template A. Second, we show that mutT-induced A.T-->C.G transversions are significantly reduced in strains carrying mutY and mutMmutY deficiencies suggesting that 8-oxoG, when present in DNA, preferentially mispairs with dATP. Third, the mutY and mutMmutY deficiencies also decrease A.T-->C.G transversions in the mutT(+) background, suggesting that, even in the presence of functional MutT protein, A.T-->C.G transversions may still result from 8-oxodGTP misincorporation.
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Affiliation(s)
- Robert G Fowler
- Department of Biological Sciences, San Jose State University, San Jose, CA 95192, USA.
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Kamiya H. Mutagenic potentials of damaged nucleic acids produced by reactive oxygen/nitrogen species: approaches using synthetic oligonucleotides and nucleotides: survey and summary. Nucleic Acids Res 2003; 31:517-31. [PMID: 12527759 PMCID: PMC140503 DOI: 10.1093/nar/gkg137] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
DNA and DNA precursors (deoxyribonucleotides) suffer damage by reactive oxygen/nitrogen species. They are important mutagens for organisms, due to their endogenous formation. Damaged DNA and nucleotides cause alterations of the genetic information by the mispairing properties of the damaged bases, such as 8-hydroxyguanine (7,8-dihydro-8-oxoguanine) and 2-hydroxyadenine. Here, the author reviews the mutagenic potentials of damaged bases in DNA and of damaged DNA precursors formed by reactive oxygen/nitrogen species, focusing on the results obtained with synthetic oligonucleotides and 2'-deoxyribonucleoside 5'-triphosphates.
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Affiliation(s)
- Hiroyuki Kamiya
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan.
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Yamada NA, Parker JM, Farber RA. Mutation frequency analysis of mononucleotide and dinucleotide repeats after oxidative stress. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2003; 42:75-84. [PMID: 12929119 DOI: 10.1002/em.10179] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Many tumors exhibit genetic instability at the DNA sequence level in the form of frameshift mutations in simple repeats (microsatellite instability). A high level of microsatellite instability, such as that seen in hereditary nonpolyposis colorectal cancer (HNPCC), arises from defects in the mismatch repair pathway. A low level of microsatellite instability is found in some non-HNPCC-associated cancers, such as those of the breast and lung, and is not attributable to mismatch repair defects. We hypothesized that oxidative DNA damage may be at least partly responsible for the generation of microsatellite mutations in these tumors. We investigated whether oxidative DNA damage can induce microsatellite mutations in mismatch repair-proficient cultured cells. Telomerase-immortalized normal human fibroblasts were stably transfected with a plasmid containing a tk-neo fusion gene, such that the neo coding region was placed out of frame by the presence of an upstream microsatellite sequence. Cells were treated with H(2)O(2) and mutation frequencies were determined for G(17), A(17), and (CA)(17) repeats. Mutation frequencies of mononucleotide repeats in cells with the neo gene in the (+1) reading frame were reduced after treatment. No effect was observed in cells with the mononucleotide repeats in the (-1) reading frame. A small increase in mutation frequency was observed in cells with the (CA)(17) repeat. Our data suggest that diploid human cells may have protective mechanisms that prevent the induction of microsatellite mutations by a short exposure to high levels of oxidative stress.
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Affiliation(s)
- Nazumi A Yamada
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Kornyushyna O, Berges AM, Muller JG, Burrows CJ. In vitro nucleotide misinsertion opposite the oxidized guanosine lesions spiroiminodihydantoin and guanidinohydantoin and DNA synthesis past the lesions using Escherichia coli DNA polymerase I (Klenow fragment). Biochemistry 2002; 41:15304-14. [PMID: 12484769 DOI: 10.1021/bi0264925] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The low redox potential of 8-oxo-7,8-dihydroguanine (OG), a molecule regarded as a marker of oxidative damage in cells, makes it an easy target for further oxidation. Using a temperature-dependent method of synthesis, the oxidation products of OG, guanidinohydantoin (Gh) and/or its isomer iminoallantoin (Ia) as well as spiroiminodihydantoin (Sp), have been site-specifically incorporated into DNA oligomers. Single nucleotide insertion and primer extension experiments using Escherichia coli Kf exo(-) DNA polymerase were carried out under "standing start" and "running start" conditions in various sequence contexts. dAMP and dGMP were found to be inserted opposite these OG oxidation products. Steady-state kinetic studies show that the Gh/Ia.G base pair yields a lower K(m) value compared to the Sp.G pair or X.A (X = Gh/Ia or Sp). Running start experiments using oxidized and unoxidized OG-containing templates showed enhanced full extension in the presence of all four dNTPs. A sequence preference for efficiency of extension was found when Gh/Ia and Sp are present in the DNA template, possibly leading to primer misalignment. Full extension is more efficient for the templates containing two Gs immediately 3' to the lesions compared to two As. Although these lesions cause a significant block for DNA elongation, results show that they are more easily bypassed by the polymerase when situated in the appropriate sequence context. UV melting studies carried out on duplexes mimicking the template/primer systems were used to characterize thermal stability of the duplexes. These experiments suggest that both Gh/Ia and Sp destabilize the duplex to a much greater extent than OG, with Sp being most severe.
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Affiliation(s)
- Olga Kornyushyna
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
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Servant L, Cazaux C, Bieth A, Iwai S, Hanaoka F, Hoffmann JS. A role for DNA polymerase beta in mutagenic UV lesion bypass. J Biol Chem 2002; 277:50046-53. [PMID: 12388548 DOI: 10.1074/jbc.m207101200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report here that DNA polymerase beta (pol beta), the base excision repair polymerase, is highly expressed in human melanoma tissues, known to be associated with UV radiation exposure. To investigate the potential role of pol beta in UV-induced genetic instability, we analyzed the cellular and molecular effects of excess pol beta. We firstly demonstrated that mammalian cells overexpressing pol beta are resistant and hypermutagenic after UV irradiation and that replicative extracts from these cells are able to catalyze complete translesion replication of a thymine-thymine cyclobutane pyrimidine dimer (CPD). By using in vitro primer extension reactions with purified pol beta, we showed that CPD as well as, to a lesser extent, the thymine-thymine pyrimidine-pyrimidone (6-4) photoproduct, were bypassed. pol beta mostly incorporates the correct dATP opposite the 3'-terminus of both CPD and the (6-4) photoproduct but can also misinsert dCTP at a frequency of 32 and 26%, respectively. In the case of CPD, efficient and error-prone extension of the correct dATP was found. These data support a biological role of pol beta in UV lesion bypass and suggest that deregulated pol beta may enhance UV-induced genetic instability.
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Affiliation(s)
- Laurence Servant
- Group "Genetic instability and cancer" at the Institut de Pharmacologie et Biologie Structurale, UMR CNRS 5089, 31077 Toulouse cédex 4, France
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Holmes EW, Bingham CM, Cunningham ML. Hepatic expression of polymerase beta, Ref-1, PCNA, and Bax in WY 14,643-exposed rats and hamsters. Exp Mol Pathol 2002; 73:209-19. [PMID: 12565796 DOI: 10.1006/exmp.2002.2477] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hepatic levels of three protein markers of oxidative stress, polymerase beta, Ref-1, and PCNA, and of the pro-apoptotic protein, Bax, were quantitated after exposure to WY 14,643 (500 ppm in the feed) for 6 or 34 days in a rodent that is susceptible peroxisome proliferator (PP)-induced liver tumors (the Sprague Dawley rat) and in a rodent that is relatively resistant PP-induced liver tumors (the Syrian hamster). The analysis of detergent-extracted whole liver homogenates by immunoblotting showed a marked increase in the abundance of a 45-kDa variant of polymerase beta immunoreactivity and significant increases in the expression of Ref-1 and PCNA in WY 14,643-exposed rats. In contrast. WY 14,643-exposed hamsters expressed only trace levels of the polymerase beta variant and showed significant decreases in the expression of Ref-1 and PCNA. Long-term WY 14,643 exposure was associated with marked decreases in Bax expression in both species. Dose-response studies in the rat showed that the hepatic expression of the polymerase beta and Ref-1 were significantly increased after 6 days of exposure to WY 14,643 at levels of 5 and 50 ppm, respectively. The analysis of subcellular fractions of rat liver showed that the pathological increases in the levels of polymerase beta, Ref-1, and PCNA were especially prominent in mitochondria-enriched particulate liver subfractions. These results indicate that WY 14,643 exposure is associated with an increase in oxidative stress to the liver and that liver mitochondria are a major target of WY 14,643-associated liver damage. Our data are consistent with the hypothesis that the chronic overexpression of mutagenic or oncogenic effectors like polymerase beta and Ref-1 in a setting of increased hepatocyte proliferation and decreased apoptosis may facilitate peroxisome proliferator-induced hepatocellular carcinoma in the rat.
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Affiliation(s)
- E W Holmes
- Department of Pathology, Loyola University Stritch School of Medicine, Maywood, Illinois 60153, USA
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Lee DH, O'Connor TR, Pfeifer GP. Oxidative DNA damage induced by copper and hydrogen peroxide promotes CG-->TT tandem mutations at methylated CpG dinucleotides in nucleotide excision repair-deficient cells. Nucleic Acids Res 2002; 30:3566-73. [PMID: 12177298 PMCID: PMC134245 DOI: 10.1093/nar/gkf478] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Oxidative DNA damage may play an important role in human disease including cancer. Previously, mutational spectra have been determined using systems that include transition metal ions and hydrogen peroxide (H2O2). G-->T transversions and C-->T transitions were the most common mutations observed including some CC-->TT tandem mutations. C-->T transition mutations at methylated CpG dinucleotides are the most common mutations in human genetic diseases. It has been hypothesized that oxidative stress may increase the frequency of mutations at methylated CpG sequences. Here we have used a CpG-methylated shuttle vector to derive mutational spectra of copper/H2O2-induced DNA damage upon passage of the shuttle vector through human fibroblasts. We find that copper/H2O2 treatment produces higher numbers of CpG transition mutations when the CpGs are methylated but does not create clear C-->T hotspots at these sites. More strikingly, we observed that this treatment produces a substantial frequency of mutations that were mCG-->TT tandem mutations. Six of seven tandem mutations were of this type. mCG-->TT mutations (6/63 = 10% of all mutations) were observed only in nucleotide excision repair-deficient (XP-A) cells but were not found in repair-proficient cells. The data suggest that this novel type of mutation may be produced by vicinal or cross-linked base damage involving 5-methylcytosine and a neighboring guanine, which is repaired by nucleotide excision repair. We suggest that the underlying oxidative lesions could be responsible for the progressive neurodegeneration seen in XP-A individuals.
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Affiliation(s)
- Dong-Hyun Lee
- Department of Biology, Beckman Research Institute of the City of Hope, 1450 East Duarte Road, Duarte, CA 91010, USA
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Parlanti E, Fortini P, Macpherson P, Laval J, Dogliotti E. Base excision repair of adenine/8-oxoguanine mispairs by an aphidicolin-sensitive DNA polymerase in human cell extracts. Oncogene 2002; 21:5204-12. [PMID: 12149642 DOI: 10.1038/sj.onc.1205561] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2002] [Revised: 03/06/2002] [Accepted: 03/28/2002] [Indexed: 11/08/2022]
Abstract
Replication of DNA containing 8-oxo-7,8-dihydroguanine (8oxoG) can generate 8oxoG/A base pairs which, if uncorrected, lead to G-->T transversions. It is generally accepted that the repair of these promutagenic base pairs in human cells is initiated by the MutY DNA glycosylase homolog (hMYH). Here we provide biochemical evidence that human cell extracts perform base excision repair (BER) on both DNA strands of an 8oxoG/A mismatch. At early repair times the specificity of nucleotide incorporation indicates a preferential insertion of C opposite 8oxoG leading to the formation of 8oxoG/C pairs. This is followed by repair synthesis on the opposite DNA strand that is consistent with hOGG1-mediated correction of 8oxoG/C to G/C. Repair synthesis on either strand is completely inhibited by aphidicolin suggesting that a replicative DNA polymerase is involved in the gap filling. This is the first demonstration that repair of 8oxoG/A base pairs is by two BER events likely mediated by Poldelta/epsilon. We suggest that the Poldelta/epsilon-mediated BER is the general mode of repair when BER lesions are formed at replication forks.
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Affiliation(s)
- Eleonora Parlanti
- Laboratory of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita', Viale Regina Elena 299, 00161 Rome, Italy
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Chiapperino D, Kroth H, Kramarczuk IH, Sayer JM, Masutani C, Hanaoka F, Jerina DM, Cheh AM. Preferential misincorporation of purine nucleotides by human DNA polymerase eta opposite benzo[a]pyrene 7,8-diol 9,10-epoxide deoxyguanosine adducts. J Biol Chem 2002; 277:11765-71. [PMID: 11821420 DOI: 10.1074/jbc.m112139200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human DNA polymerase eta was used to copy four stereoisomeric deoxyguanosine (dG) adducts derived from benzo[a]pyrene 7,8-diol 9,10-epoxide (diastereomer with the 7-hydroxyl group and epoxide oxygen trans (BaP DE-2)). The adducts, formed by either cis or trans epoxide ring opening of each enantiomer of BaP DE-2 by N(2) of dG, were placed at the fourth nucleotide from the 5'-end in two 16-mer sequence contexts, 5' approximately CG*A approximately and 5' approximately GG*T. poleta was remarkably error prone at all four diol epoxide adducts, preferring to misincorporate G and A at frequencies 3- to more than 50-fold greater than the frequencies for T or the correct C, although the highest rates were 60-fold below the rate of incorporation of C opposite a non-adducted G. Anti to syn rotation of the adducted base, consistent with previous NMR data for a BaP DE-2 dG adduct placed just beyond a primer terminus, provides a rationale for preferring purine misincorporation. Extension of purine misincorporations occurred preferentially, but extension beyond the adduct site was weak with V(max)/K(m) values generally 10-fold less than for misincorporation. Mostly A was incorporated opposite (+)-BaP DE-2 dG adducts, which correlates with published observations that G --> T is the most common type of mutation that (+)-BaP DE-2 induces in mammalian cells.
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Affiliation(s)
- Dominic Chiapperino
- Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA
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