title: Psoralen adducts induced by triplex-forming oligonucleotides are refractory to repair in HeLa cells.
abstract: The use of triple helix-forming oligonucleotides constitutes an attractive strategy to regulate gene expression by inhibition of transcription. Psoralen-oligonucleotide conjugates form, upon irradiation, covalent triplexes and thereby modify the specific target sequence. The processing of such photoproducts on the promoter of the gene coding for the interleukin-2 receptor alpha chain was investigated in HeLa cells and HeLa nuclear extracts. We demonstrate that psoralen cross-links are not repaired within the cell extracts nor inside cells. The mechanism of repair inhibition was elucidated in vitro: the presence of the third strand oligonucleotide inhibits the incision step of the damaged target by repair endonucleases. These results demonstrate the possibility of using this approach to induce a persistent intracellular DNA damage at a specific site and to afford prolonged transcription inhibition.
authors.affiliation: Laboratoire de Biophysique, INSERM U 201 - CNRS UMR 8646, Muséum National d'Histoire Naturelle, 43, rue Cuvier, Paris, 75005, France. guieysse@mnhn.fr
authors.forename: A L
authors.initials: AL
authors.lastname: Guieysse
authors.forename: D
authors.initials: D
authors.lastname: Praseuth
authors.forename: C
authors.initials: C
authors.lastname: Giovannangeli
authors.forename: U
authors.initials: U
authors.lastname: Asseline
authors.forename: C
authors.initials: C
authors.lastname: Hélène
mesh_terms: D001483:Base Sequence; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000235:genetics; D003432:Cross-Linking Reagents / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D018736:DNA Adducts / Q000378:metabolism* / Q000528:radiation effects; D004249:DNA Damage / Q000235:genetics* / Q000528:radiation effects; D015342:DNA Probes / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D011564:Furocoumarins / Q000378:metabolism* / Q000528:radiation effects; D016356:Gene Products, tax / Q000378:metabolism; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000528:radiation effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D015375:Receptors, Interleukin-2 / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics / Q000528:radiation effects; D014162:Transfection; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D018736:DNA Adducts; D015342:DNA Probes; D004268:DNA-Binding Proteins; D011564:Furocoumarins; D016356:Gene Products, tax; D009838:Oligodeoxyribonucleotides; D017319:Photosensitizing Agents; D015375:Receptors, Interleukin-2; C056465:psoralen-DNA adduct; C051802:triplex DNA; D004247:DNA; D008156:Luciferases