title: Mechanisms underlying targeted gene correction using chimeric RNA/DNA and single-stranded DNA oligonucleotides.
abstract: Chimeric RNA/DNA oligonucleotides and modified single-stranded oligonucleotides have been developed for site-specific correction of episomal and chromosomal target genes. The gene repair approach relies on specific hybridization of the oligonucleotides to the target gene generating a mismatch with the targeted point mutation. Restored gene function is anticipated to occur through activation of endogenous repair systems that recognize the created mismatch. We present an overview of the gene correction results obtained in several target genes by employing various oligonucleotide designs and a discussion of the possible mechanisms underlying the gene correction techniques. Experimental data suggest that modified single-stranded oligonucleotides form intermediate three-stranded heteroduplexes involving the human RecA homologue, hRad51, whereas chimeric RNA/DNA oligonucleotides may participate in three or four-stranded intermediate structures. Protein factors such as hRad52, hRad54, hRPA, and p53 may modulate the heteroduplex formation and participate in the activation of the endogenous mismatch repair and/or nucleotide excision repair pathway(s). The efficiency of the gene correction process may furthermore be influenced by the differential recognition of mismatches by repair enzymes and possible sequence context effects.
authors.affiliation: Department of Human Genetics, University of Aarhus, 8000 Aarhus C, Denmark.
authors.forename: Marie S
authors.initials: MS
authors.lastname: Andersen
authors.forename: Charlotte B
authors.initials: CB
authors.lastname: Sørensen
authors.forename: Lars
authors.initials: L
authors.lastname: Bolund
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Jensen
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D001426:Bacterial Proteins; D020137:Base Pair Mismatch; D004247:DNA / Q000494:pharmacology*; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics; D016158:Genes, p53; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008957:Models, Genetic; D051719:MutS DNA Mismatch-Binding Protein; D051718:MutS Homolog 2 Protein; D009841:Oligonucleotides / Q000494:pharmacology*; D017354:Point Mutation; D012150:Polymorphism, Restriction Fragment Length; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012313:RNA / Q000494:pharmacology*; D011995:Recombination, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D011518:Proto-Oncogene Proteins; D012313:RNA; D004247:DNA; D000251:Adenosine Triphosphatases; C497172:MSH2 protein, human; D051719:MutS DNA Mismatch-Binding Protein; D051718:MutS Homolog 2 Protein; C497175:MutS protein, E coli