Mutagenic properties of the 8-amino-2 '-deoxyguanosine DNA adduct in mammalian cells

作者：Tan XZ; Suzuki N; Johnson F; Grollman AP; Shibutani S^*

来源：Nucleic Acids Research, 1999, 27(11): 2310-2314.

DOI：10.1093/nar/27.11.2310

The DNA adduct 8-amino-2'-deoxyguanosine (8-amino-dG) is found in liver DNA of rats treated with the hepatocarcinogen 2-nitropropane. Site-specifically modified oligodeoxynucleotides were used to explore the mutagenic potential of 8-amino-dG in simian kidney (COS-7) cells. Oligodeoxynucleotides (5'-TCCTCCTX(1)G(2)CCTCTC and 5'-TCCTCCTG(1)X(2)CCTCTC, X = dG or 8-amino-dG) with the lesion positioned at codon 60 or 61 of the non-coding strand of the human c-Ha-ras1 gene were inserted into single-stranded phagemid vectors and transfected into COS-7 cells. The progeny plasmid obtained was used to transform Escherichia coli DH10B. Transformants were analyzed by oligodeoxynucleotide hybridization and DNA sequencing to establish the mutation frequency and spectrum produced by the modified base. The correct base, dCMP, was incorporated preferentially opposite 8-amino-dG at X(1) and X(2) When 8-amino-dG was at X(1), targeted G(NH2)-->T transversions were detected, along with smaller numbers of G(NH2)-->A transitions and G(NH2)-->C transversions. When the adduct was at X(2), Only G(NH2)-->T transversions were observed. The frequencies of targeted mutation at X1 and Xp were 2.7 and 1.7%, respectively. Mutation frequency and mutagenic spectrum were sequence context dependent. In addition, non-targeted G-->T transversions, accompanied by some G-->A transitions, were detected 5' to 8-amino-dG when the lesion was at XP We conclude that 8-amino-dG is a mutagenic lesion, generating G-->T and G-->C transversions and G-->A transitions in mammalian cells.

• 出版日期1999-6-1