title: Clustered sites of DNA repair synthesis during early nucleotide excision repair in ultraviolet light-irradiated quiescent human fibroblasts.
abstract: The ubiquitous process of nucleotide excision repair includes an obligatory step of DNA repair synthesis (DRS) to fill the gapped heteroduplex following excision of a short (approximately 30-nucleotide) damaged single-strand fragment. Using 5-iododeoxyuridine to label repair patches during the first 10-60 min after UV irradiation of quiescent normal human fibroblasts we have visualized a limited number of discrete foci of DRS. These must reflect clusters of elementary DRS patches, since single patches would not be detected. The DRS foci are attenuated in normal cells treated with alpha-amanitin or in Cockayne syndrome (CS) cells, which are specifically deficient in the pathway of transcription-coupled repair (TCR). It is therefore likely that the clusters of DRS arise in chromatin domains within which RNA polymerase II transcription is compartmentalized. However, we also found significant suppression of DRS foci in xeroderma pigmentosum, complementation group C cells in which global genome repair (GGR) is defective, but TCR is normal. This suggests that the TCR is responsible for the DRS cluster formation in the absence of GGR. The residual foci detected in CS cells indicate that, even at early times following UV irradiation, GGR may open some chromatin domains for processive scanning and consequent DRS independent of transcription.
authors.affiliation: Laboratory of Chromosome Stability, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia.
authors.forename: Maria
authors.initials: M
authors.lastname: Svetlova
authors.forename: Lioudmila
authors.initials: L
authors.lastname: Solovjeva
authors.forename: Nadezhda
authors.initials: N
authors.lastname: Pleskach
authors.forename: Natalia
authors.initials: N
authors.lastname: Yartseva
authors.forename: Tatyana
authors.initials: T
authors.lastname: Yakovleva
authors.forename: Nikolai
authors.initials: N
authors.lastname: Tomilin
authors.forename: Philip
authors.initials: P
authors.lastname: Hanawalt
mesh_terms: D000546:Amanitins / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism* / Q000528:radiation effects; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D002875:Chromosomes / Q000235:genetics / Q000528:radiation effects; D003057:Cockayne Syndrome / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D004247:DNA / Q000096:biosynthesis* / Q000235:genetics / Q000528:radiation effects; D004249:DNA Damage / Q000235:genetics* / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects; D006801:Humans; D007065:Idoxuridine / Q000494:pharmacology; D007399:Interphase / Q000235:genetics / Q000528:radiation effects; D008677:Metaphase / Q000235:genetics / Q000528:radiation effects; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D000546:Amanitins; D002843:Chromatin; D019384:Nucleic Acid Synthesis Inhibitors; D004247:DNA; D012319:RNA Polymerase II; D007065:Idoxuridine