title: Long-patch DNA repair synthesis during base excision repair in mammalian cells.
abstract: The base excision repair (BER) process removes base damage such as oxidation, alkylation or abasic sites. Two BER sub-pathways have been characterized using in vitro methods, and have been classified according to the length of the repair patch as either 'short-patch' BER (one nucleotide) or 'long-patch' BER (LP-BER; more than one nucleotide). To investigate the occurrence of LP-BER in vivo, we developed an assay using a plasmid containing a single modified base in the transcribed strand of the enhanced green fluorescent protein (EGFP) gene and a stop codon, based on a single-nucleotide mismatch, at varying distances on the 3' side of the lesion. The reversion of the stop codon occurs after DNA repair synthesis and restores EGFP expression after transfection of mismatch-repair-deficient cells. Repair patches longer than one nucleotide were observed for 55-80% or 80-100% of the plasmids with a mean length of 2-6 or 6-12 nucleotides for 8-oxo-7,8-dihydroguanine or a synthetic abasic site, respectively. These data show the existence of LP-BER in vivo, and emphasize the effect of the type of BER substrate lesion on both the yield and the extent of the LP-BER sub-pathway.
authors.affiliation: Institut de Pharmacologie et Ciologie Structurale, CNRS UMR, Toulouse, France.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Sattler
authors.forename: Philippe
authors.initials: P
authors.lastname: Frit
authors.forename: Bernard
authors.initials: B
authors.lastname: Salles
authors.forename: Patrick
authors.initials: P
authors.lastname: Calsou
mesh_terms: D000818:Animals; D020137:Base Pair Mismatch; D002460:Cell Line; D002468:Cell Physiological Phenomena; D004260:DNA Repair; D004261:DNA Replication; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D008322:Mammals; D013698:Templates, Genetic; D014162:Transfection
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins