Transcription domain-associated repair in human cells.
Nucleotide excision repair (NER), which is arguably the most versatile DNA repair system, is strongly attenuated in human cells of the monocytic lineage when they differentiate into macrophages. Within active genes, however, both DNA strands continue to be proficiently repaired. The proficient repair of the nontranscribed strand cannot be explained by the dedicated subpathway of transcription-coupled repair (TCR), which is targeted to the transcribed strand in expressed genes. We now report that the previously termed differentiation-associated repair (DAR) depends upon transcription, but not simply upon RNA polymerase II (RNAPII) encountering a lesion: proficient repair of both DNA strands can occur in a part of a gene that the polymerase never reaches, and even if the translocation of RNAPII is blocked with transcription inhibitors. This suggests that DAR may be a subset of global NER, restricted to the subnuclear compartments or chromatin domains within which transcription occurs. Downregulation of selected NER genes with small interfering RNA has confirmed that DAR relies upon the same genes as global genome repair, rather than upon TCR-specific genes. Our findings support the general view that the genomic domains within which transcription is active are more accessible than the bulk of the genome to the recognition and repair of lesions through the global pathway and that TCR is superimposed upon that pathway of NER.
Nouspikel
Thierry P
TP
Institute for Cancer Studies, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX, United Kingdom. t.nouspikel@sheffield.ac.uk
Hyka-Nouspikel
Nevila
N
Hanawalt
Philip C
PC
D000546:Amanitins / Q000494:pharmacology; D002454:Cell Differentiation; D047369:Chromatin Immunoprecipitation; D004249:DNA Damage; D004260:DNA Repair; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000187:drug effects; D009097:Multienzyme Complexes / Q000378:metabolism; D012320:RNA Polymerase III / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D013940:Thymidylate Synthase / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014466:Ultraviolet Rays
D000546:Amanitins; D004791:Enzyme Inhibitors; D009097:Multienzyme Complexes; D034741:RNA, Small Interfering; C056930:thymidylate synthase-dihydrofolate reductase; D004004:Dichlororibofuranosylbenzimidazole; D013762:Tetrahydrofolate Dehydrogenase; D013940:Thymidylate Synthase; D012320:RNA Polymerase III; D013755:Tetradecanoylphorbol Acetate