Effect of G:C-->A:T transition, potentially arising from O6-guanine alkylation, in the transcription regulation of c-fos serum response element.
O6-meGs, if not repaired before cell undergo DNA synthesis, can cause erroneous pairing of thymine resulting in a G:C-->A:T transition, after the next DNA replication. It is known that the presence of O6-meG in promoter sequences inhibits the specific binding of transcription factors. Little is known on the effect of G:C-->A:T transitions on this binding. c-fos SRE was used as a model to study the effect of different G:C-->A:T transitions (at the positions -305, -306, -316, -319 and -320) in terms of SRE specific DNA-binding and functional ability to activate transcription of a reporter gene. The electromobility shift assay and a transient transfection assay were used. The G:C-->A:T transition at -320 caused 92% inhibition, while mutations at the positions -305, -306, -316 and -319 caused respectively 55, 43, 19 and 44% inhibition. The findings indicate that some G:C-->A:T transitions, potentially arising from O6-guanine methylation, can impair the regulation of c-fos transcription.
Bonfanti
M
M
Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Colella
G
G
Broggini
M
M
D'Incalci
M
M
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D004261:DNA Replication; D017930:Genes, Reporter; D016762:Genes, fos; D006147:Guanine / Q000031:analogs & derivatives*; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection
D017931:DNA Primers; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D011993:Recombinant Fusion Proteins; D006147:Guanine; C008449:O-(6)-methylguanine