Title: Next-generation sequencing reveals the biological significance of the N(2),3-ethenoguanine lesion in vivo.
Authors: Chang, Shiou-chi; Fedeles, Bogdan I; Wu, Jie; Delaney, James C; Li, Deyu; Zhao, Linlin; Christov, Plamen P; Yau, Emily; Singh, Vipender; Jost, Marco; Drennan, Catherine L; Marnett, Lawrence J; Rizzo, Carmelo J; Levine, Stuart S; Guengerich, F Peter; Essigmann, John M
Published In Nucleic Acids Res, (2015 Jun 23)
Abstract: Etheno DNA adducts are a prevalent type of DNA damage caused by vinyl chloride (VC) exposure and oxidative stress. Etheno adducts are mutagenic and may contribute to the initiation of several pathologies; thus, elucidating the pathways by which they induce cellular transformation is critical. Although N(2),3-ethenoguanine (N(2),3-εG) is the most abundant etheno adduct, its biological consequences have not been well characterized in cells due to its labile glycosidic bond. Here, a stabilized 2'-fluoro-2'-deoxyribose analog of N(2),3-εG was used to quantify directly its genotoxicity and mutagenicity. A multiplex method involving next-generation sequencing enabled a large-scale in vivo analysis, in which both N(2),3-εG and its isomer 1,N(2)-ethenoguanine (1,N(2)-εG) were evaluated in various repair and replication backgrounds. We found that N(2),3-εG potently induces G to A transitions, the same mutation previously observed in VC-associated tumors. By contrast, 1,N(2)-εG induces various substitutions and frameshifts. We also found that N(2),3-εG is the only etheno lesion that cannot be repaired by AlkB, which partially explains its persistence. Both εG lesions are strong replication blocks and DinB, a translesion polymerase, facilitates the mutagenic bypass of both lesions. Collectively, our results indicate that N(2),3-εG is a biologically important lesion and may have a functional role in VC-induced or inflammation-driven carcinogenesis.
PubMed ID: 25837992
MeSH Terms: DNA Adducts/chemistry; DNA Damage*; DNA Polymerase beta/metabolism; DNA Repair; DNA Repair Enzymes/metabolism; Dioxygenases/metabolism; Guanine/analogs & derivatives*; Guanine/chemistry; High-Throughput Nucleotide Sequencing; Mutagenesis; Mutation*; Sequence Analysis, DNA; Sequence Deletion