title: Mutagenicity of 5-formylcytosine, an oxidation product of 5-methylcytosine, in DNA in mammalian cells.
abstract: To examine the mutagenicity of 5-formylcytosine (5-fC), an oxidation product of 5-methylcytosine (5-mC), 5-fC was incorporated into predetermined sites of double-stranded shuttle vectors. The nucleotide sequences in which the modified base was incorporated were 5'-AFGCGT-3' and 5'-ACGFGT-3' (F represents 5-fC), the recognition site for the restriction enzyme MluI (5'-ACGCGT-3'). 5-fC was incorporated into the template strand of either the leading or lagging strand of DNA replication. The modified DNAs were transfected into simian COS-7 cells, and the DNAs replicated in the cells were recovered and analyzed after a second transfection into Escherichia coli. 5-fC weakly blocked DNA replication in mammalian cells. The 5-fC residues were mutagenic, with mutation frequencies in double-stranded vectors of 0.03-0.28%. The mutation spectrum of 5-fC was broad, and included targeted (5-fC-->G, 5-fC-->A, and 5-fC-->T) and untargeted mutations. These results suggest that the oxidation of 5-mC results in mutations at and around the modified sites.
mesh_terms: D044503:5-Methylcytosine; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D003596:Cytosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000633:toxicity*; D004249:DNA Damage; D004261:DNA Replication / Q000187:drug effects; D005822:Genetic Vectors / Q000737:chemistry / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010084:Oxidation-Reduction; D010957:Plasmids / Q000235:genetics; D013698:Templates, Genetic; D014162:Transfection
chemical_list: D009153:Mutagens; D009838:Oligodeoxyribonucleotides; D044503:5-Methylcytosine; D003596:Cytosine