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Ohno M, Takano N, Hidaka K, Sasaki F, Yamauchi K, Aoki Y, Nohmi T, Nakabeppu Y, Nakatsu Y, Tsuzuki T. Oxidative stress accelerates intestinal tumorigenesis by enhancing 8-oxoguanine-mediated mutagenesis in MUTYH-deficient mice. Genome Res 2024; 34:47-56. [PMID: 38290979 PMCID: PMC10904009 DOI: 10.1101/gr.278326.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/02/2024] [Indexed: 02/01/2024]
Abstract
Oxidative stress-induced DNA damage and its repair systems are related to cancer etiology; however, the molecular basis triggering tumorigenesis is not well understood. Here, we aimed to explore the causal relationship between oxidative stress, somatic mutations in pre-tumor-initiated normal tissues, and tumor incidence in the small intestines of MUTYH-proficient and MUTYH-deficient mice. MUTYH is a base excision repair enzyme associated with human colorectal cancer. Mice were administered different concentrations of potassium bromate (KBrO3; an oxidizing agent)-containing water for 4 wk for mutagenesis studies or 16 wk for tumorigenesis studies. All Mutyh -/- mice treated with >0.1% KBrO3 developed multiple tumors, and the average tumor number increased dose dependently. Somatic mutation analysis of Mutyh -/-/rpsL transgenic mice revealed that G:C > T:A transversion was the only mutation type correlated positively with KBrO3 dose and tumor incidence. These mutations preferentially occurred at 5'G in GG and GAA sequences in rpsL This characteristic mutation pattern was also observed in the genomic region of Mutyh -/- tumors using whole-exome sequencing. It closely corresponded to signature 18 and SBS36, typically caused by 8-oxo-guanine (8-oxoG). 8-oxoG-induced mutations were sequence context dependent, yielding a biased amino acid change leading to missense and stop-gain mutations. These mutations frequently occurred in critical amino acid codons of known cancer drivers, Apc or Ctnnb1, known for activating Wnt signal pathway. Our results indicate that oxidative stress contributes to increased tumor incidence by elevating the likelihood of gaining driver mutations by increasing 8-oxoG-mediated mutagenesis, particularly under MUTYH-deficient conditions.
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Affiliation(s)
- Mizuki Ohno
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan;
| | - Noriko Takano
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
| | - Kyoko Hidaka
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
- Center for Fundamental Education, The University of Kitakyushu, Kitakyushu, Fukuoka 802-8577, Japan
| | - Fumiko Sasaki
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
| | - Kazumi Yamauchi
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
- Department of Radiobiology, Institute for Environmental Sciences, Kamikita, Aomori 039-3212, Japan
| | - Yasunobu Aoki
- Health and Environmental Risk Division, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
| | - Takehiko Nohmi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kawasaki, Kanagawa 210-9501, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
- Japan Society for the Promotion of Science, San Francisco Office, Berkeley, California 94704, USA
| | - Yoshimichi Nakatsu
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
| | - Teruhisa Tsuzuki
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
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Schmaltz LF, Koag MC, Kou Y, Zhang L, Lee S. Genotoxic effects of the major alkylation damage N7-methylguanine and methyl formamidopyrimidine. Biochem J 2023; 480:573-585. [PMID: 37078496 PMCID: PMC11061863 DOI: 10.1042/bcj20220460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 03/29/2023] [Accepted: 04/19/2023] [Indexed: 04/21/2023]
Abstract
Various alkylating agents are known to preferentially modify guanine in DNA, resulting in the formation of N7-alkylguanine (N7-alkylG) and the imidazole ring opened alkyl-formamidopyrimidine (alkyl-FapyG) lesions. Evaluating the mutagenic effects of N7-alkylG has been challenging due to the instability of the positively charged N7-alkylG. To address this issue, we developed a 2'-fluorine-mediated transition-state destabilization approach, which stabilizes N7-alkylG and prevents spontaneous depurination. We also developed a postsynthetic conversion of 2'-F-N7-alkylG DNA into 2'-F-alkyl-FapyG DNA. Using these methods, we incorporated site-specific N7-methylG and methyl-FapyG into pSP189 plasmid and determined their mutagenic properties in bacterial cells using the supF-based colony screening assay. The mutation frequency of N7-methylG was found to be less than 0.5%. Our crystal structure analysis revealed that N7-methylation did not significantly alter base pairing properties, as evidenced by a correct base pairing between 2'-F-N7-methylG and dCTP in Dpo4 polymerase catalytic site. In contrast, the mutation frequency of methyl-FapyG was 6.3%, highlighting the mutagenic nature of this secondary lesion. Interestingly, all mutations arising from methyl-FapyG in the 5'-GGT(methyl-FapyG)G-3' context were single nucleotide deletions at the 5'-G of the lesion. Overall, our results demonstrate that 2'-fluorination technology is a useful tool for studying the chemically labile N7-alkylG and alkyl-FapyG lesions.
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Affiliation(s)
- Lillian F Schmaltz
- From the Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, U.S.A
| | - Myong-Chul Koag
- From the Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, U.S.A
| | - Yi Kou
- From the Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, U.S.A
| | - Louis Zhang
- From the Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, U.S.A
| | - Seongmin Lee
- From the Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, U.S.A
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Bacurio JHT, Yang H, Naldiga S, Powell BV, Ryan BJ, Freudenthal BD, Greenberg MM, Basu AK. Sequence context effects of replication of Fapy•dG in three mutational hot spot sequences of the p53 gene in human cells. DNA Repair (Amst) 2021; 108:103213. [PMID: 34464900 DOI: 10.1016/j.dnarep.2021.103213] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 01/01/2023]
Abstract
Fapy•dG and 8-OxodGuo are formed in DNA from a common N7-dG radical intermediate by reaction with hydroxyl radical. Although cellular levels of Fapy•dG are often greater, its effects on replication are less well understood than those of 8-OxodGuo. In this study plasmid DNA containing Fapy•dG in three mutational hotspots of human cancers, codons 248, 249, and 273 of the p53 tumor suppressor gene, was replicated in HEK 293T cells. TLS efficiencies for the Fapy•dG containing plasmids varied from 72 to 89%, and were further reduced in polymerase-deficient cells. The mutation frequency (MF) of Fapy•dG ranged from 7.3 to 11.6%, with G→T and G→A as major mutations in codons 248 and 249 compared to primarily G→T in codon 273. Increased MF in hPol ι-, hPol κ-, and hPol ζ-deficient cells suggested that these polymerases more frequently insert the correct nucleotide dC opposite Fapy•dG, whereas decreased G→A in codons 248 and 249 and reduction of all mutations in codon 273 in hPol λ-deficient cells indicated hPol λ's involvement in Fapy•dG mutagenesis. In vitro kinetic analysis using isolated translesion synthesis polymerases and hPol λ incompletely corroborated the mutagenesis experiments, indicating codependence on other proteins in the cellular milieu. In conclusion, Fapy•dG mutagenesis is dependent on the DNA sequence context, but its bypass by the TLS polymerases is largely error-free.
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Affiliation(s)
| | - Haozhe Yang
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Spandana Naldiga
- Department of Chemistry, University of Connecticut, Storrs, CT, 06269, USA
| | - Brent V Powell
- Department of Chemistry, University of Connecticut, Storrs, CT, 06269, USA
| | - Benjamin J Ryan
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Ashis K Basu
- Department of Chemistry, University of Connecticut, Storrs, CT, 06269, USA.
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Sung RJ, Zhang M, Qi Y, Verdine GL. Sequence-dependent structural variation in DNA undergoing intrahelical inspection by the DNA glycosylase MutM. J Biol Chem 2012; 287:18044-54. [PMID: 22465958 DOI: 10.1074/jbc.m111.313635] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MutM, a bacterial DNA-glycosylase, plays a critical role in maintaining genome integrity by catalyzing glycosidic bond cleavage of 8-oxoguanine (oxoG) lesions to initiate base excision DNA repair. The task faced by MutM of locating rare oxoG residues embedded in an overwhelming excess of undamaged bases is especially challenging given the close structural similarity between oxoG and its normal progenitor, guanine (G). MutM actively interrogates the DNA to detect the presence of an intrahelical, fully base-paired oxoG, whereupon the enzyme promotes extrusion of the target nucleobase from the DNA duplex and insertion into the extrahelical active site. Recent structural studies have begun to provide the first glimpse into the protein-DNA interactions that enable MutM to distinguish an intrahelical oxoG from G; however, these initial studies left open the important question of how MutM can recognize oxoG residues embedded in 16 different neighboring sequence contexts (considering only the 5'- and 3'-neighboring base pairs). In this study we set out to understand the manner and extent to which intrahelical lesion recognition varies as a function of the 5'-neighbor. Here we report a comprehensive, systematic structural analysis of the effect of the 5'-neighboring base pair on recognition of an intrahelical oxoG lesion. These structures reveal that MutM imposes the same extrusion-prone ("extrudogenic") backbone conformation on the oxoG lesion irrespective of its 5'-neighbor while leaving the rest of the DNA relatively free to adjust to the particular demands of individual sequences.
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Affiliation(s)
- Rou-Jia Sung
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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Lim KS, Taghizadeh K, Wishnok JS, Babu IR, Shafirovich V, Geacintov NE, Dedon PC. Sequence-dependent variation in the reactivity of 8-Oxo-7,8-dihydro-2'-deoxyguanosine toward oxidation. Chem Res Toxicol 2011; 25:366-73. [PMID: 22103813 DOI: 10.1021/tx200422g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The goal of this study was to define the effect of DNA sequence on the reactivity of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) toward oxidation. To this end, we developed a quadrupole/time-of-flight (QTOF) mass spectrometric method to quantify the reactivity of site specifically modified oligodeoxyribonucleotides with two model oxidants: nitrosoperoxycarbonate (ONOOCO(2)(-)), a chemical mediator of inflammation, and photoactivated riboflavin, a classical one-electron oxidant widely studied in mutagenesis and charge transport in DNA. In contrast to previous observations with guanine [ Margolin , Y. , ( 2006 ) Nat. Chem. Biol. 2 , 365 ], sequence context did not affect the reactivity of ONOOCO(2)(-) with 8-oxodG, but photosensitized riboflavin showed a strong sequence preference in its reactivity with the following order (8-oxodG = O): COA ≈ AOG > GOG ≥ COT > TOC > AOC. That the COA context was the most reactive was unexpected and suggests a new sequence context where mutation hotspots might occur. These results point to both sequence- and agent-specific effects on 8-oxodG oxidation.
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Affiliation(s)
- Kok Seong Lim
- Department of Biological Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
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Mashimo K, Nagata Y, Kawata M, Iwasaki H, Yamamoto K. Role of the RuvAB protein in avoiding spontaneous formation of deletion mutations in the Escherichia coli K-12 endogenous tonB gene. Biochem Biophys Res Commun 2004; 323:197-203. [PMID: 15351721 DOI: 10.1016/j.bbrc.2004.08.078] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Indexed: 11/17/2022]
Abstract
The endogenous tonB gene of Escherichia coli was used as a target for spontaneous deletion mutations which were isolated from ruvAB-, recG-, and ruvC- cells. The rates of tonB mutation were essentially the same in ruv+, ruvAB-, recG-, and ruvC- cells. We analyzed tonB mutants by sequencing. In the ruv+, recG-, and ruvC- strains, the spectra were different from those obtained from the ruvAB- cells, where deletions dominated followed by IS insertions, base substitutions, and frameshifts, in that order. We then analyzed the tonB-trp large deletion, due to simultaneous mutations of the trp operon, and found that the frequency in ruvAB- was higher than those in ruv+, recG-, and ruvC- cells. To characterize deletion formation further, we analyzed all the tonB mutants from one colicin plate. Seven deletions were identified at five sites from the 45 tonB mutants of ruv+ cells and 24 deletions at 11 sites from the 43 tonB mutants of ruvAB- cells. Thus, the ruvAB- strain is a deletion mutator. We discuss the role of RuvAB in avoiding deletions.
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Affiliation(s)
- Kazumi Mashimo
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
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Nunoshiba T, Watanabe T, Nakabeppu Y, Yamamoto K. Mutagenic target for hydroxyl radicals generated in Escherichia coli mutant deficient in Mn- and Fe- superoxide dismutases and Fur, a repressor for iron-uptake systems. DNA Repair (Amst) 2002; 1:411-418. [PMID: 12530376 DOI: 10.1016/s1568-7864(02)00014-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We previously reported that mutations in Mn- and Fe-superoxide dismutases and Fur, a repressor for iron uptake systems, simulated generation of hydroxyl radicals, and caused hypermutability in Escherichia coli. The predominant type of spontaneous mutation was GC --> TA, followed by AT --> CG, suggesting the involvement of 7,8-dihydro-8-oxoguanine (8-oxoG) and 1,2-dihydro-2-oxoadenine (2-oxoA) in DNA as well as 7,8-dihydro-8-oxodeoxyguanosine triphosphate (8-oxodGTP) and 1,2-dihydro-2-oxodeoxyadenosine triphosphate (2-oxodATP) in the nucleotide pool. To determine the targets contributing to oxidative mutagenesis, DNA or nucleotides, we characterized spontaneous mutations and compared the distribution to those in mutMY and mutT strains, in which GC --> TA and AT --> CG were predominantly induced, respectively. The hotspots and sequence contexts where AT --> CG occurred frequently in sodAB fur strain were almost identical to those in mutT strain,whereas, those where GC --> TA occurred frequently in sodAB fur strain were quite different from those in mutMY strain. These observations suggested that AT --> CG is due to 8-oxodGTP, while GC --> TA is produced by some other lesion(s). The 2-oxodATP is also a major oxidative lesion in nucleotides, and strongly induces GC --> TA. The expression of cDNA for MTH1, which can hydrolyze 2-oxodATP as well as 8-oxodGTP, partially but significantly, suppressed the GC --> TA mutator phenotype of the sodAB fur strain, whereas, it did not for the mutMY strain. Additionally, the sequence contextby 2-oxodATP in E. coli was similar to that in sodAB fur strain. These results suggested that the targets contributing to oxidative mutagenesis in sodAB fur strain are nucleotides such as dGTP and dATP, rather than DNA.
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Affiliation(s)
- Tatsuo Nunoshiba
- Department of Biomolecular Science, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan.
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