title: Triplex targeted genomic crosslinks enter separable deletion and base substitution pathways.
abstract: We have synthesized triple helix forming oligonucleotides (TFOs) that target a psoralen (pso) interstrand crosslink to a specific chromosomal site in mammalian cells. Mutagenesis of the targeted crosslinks results in base substitutions and deletions. Identification of the gene products involved in mutation formation is important for developing practical applications of pso-TFOs, and may be informative about the metabolism of other interstrand crosslinks. We have studied mutagenesis of a pso-TFO genomic crosslink in repair proficient and deficient cells. Deficiencies in non homologous end joining and mismatch repair do not influence mutation patterns. In contrast, the frequency of base substitutions is dependent on the activity of ERCC1/XPF and polymerase zeta, but independent of other nucleotide excision repair (NER) or transcription coupled repair (TCR) genes. In NER/TCR deficient cells the frequency of deletions rises, indicating that in wild-type cells NER/TCR functions divert pso-TFO crosslinks from processes that result in deletions. We conclude that targeted pso-TFO crosslinks can enter genetically distinct mutational routes that resolve to base substitutions or deletions.
authors.affiliation: Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr, Baltimore, MD 21224, USA.
authors.forename: Sally
authors.initials: S
authors.lastname: Richards
authors.forename: Su-Ting
authors.initials: ST
authors.lastname: Liu
authors.forename: Alokes
authors.initials: A
authors.lastname: Majumdar
authors.forename: Ji-Lan
authors.initials: JL
authors.lastname: Liu
authors.forename: Rodney S
authors.initials: RS
authors.lastname: Nairn
authors.forename: Michel
authors.initials: M
authors.lastname: Bernier
authors.forename: Veronica
authors.initials: V
authors.lastname: Maher
authors.forename: Michael M
authors.initials: MM
authors.lastname: Seidman
mesh_terms: D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003432:Cross-Linking Reagents; D004247:DNA / Q000737:chemistry; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000502:physiology; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D005363:Ficusin / Q000494:pharmacology; D016193:G1 Phase; D023281:Genomics; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D016296:Mutagenesis; D009154:Mutation; D009841:Oligonucleotides / Q000737:chemistry*; D017384:Sequence Deletion
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D009841:Oligonucleotides; C051802:triplex DNA; C095888:xeroderma pigmentosum group F protein; D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase; C425929:DNA polymerase zeta; D004259:DNA-Directed DNA Polymerase; D005363:Ficusin