title: Spatial organization of nucleotide excision repair proteins after UV-induced DNA damage in the human cell nucleus.
abstract: Nucleotide excision repair (NER) is an evolutionary conserved DNA repair system that is essential for the removal of UV-induced DNA damage. In this study we investigated how NER is compartmentalized in the interphase nucleus of human cells at the ultrastructural level by using electron microscopy in combination with immunogold labeling. We analyzed the role of two nuclear compartments: condensed chromatin domains and the perichromatin region. The latter contains transcriptionally active and partly decondensed chromatin at the surface of condensed chromatin domains. We studied the distribution of the damage-recognition protein XPC and of XPA, which is a central component of the chromatin-associated NER complex. Both XPC and XPA rapidly accumulate in the perichromatin region after UV irradiation, whereas only XPC is also moderately enriched in condensed chromatin domains. These observations suggest that DNA damage is detected by XPC throughout condensed chromatin domains, whereas DNA-repair complexes seem preferentially assembled in the perichromatin region. We propose that UV-damaged DNA inside condensed chromatin domains is relocated to the perichromatin region, similar to what has been shown for DNA replication. In support of this, we provide evidence that UV-damaged chromatin domains undergo expansion, which might facilitate the translocation process. Our results offer novel insight into the dynamic spatial organization of DNA repair in the human cell nucleus.
authors.affiliation: Centre of Electron Microscopy, University of Lausanne, 27 Bugnon, CH-1005 Lausanne, Switzerland.
authors.forename: Liliana
authors.initials: L
authors.lastname: Solimando
authors.forename: Martijn S
authors.initials: MS
authors.lastname: Luijsterburg
authors.forename: Lorella
authors.initials: L
authors.lastname: Vecchio
authors.forename: Wim
authors.initials: W
authors.lastname: Vermeulen
authors.forename: Roel
authors.initials: R
authors.lastname: van Driel
authors.forename: Stanislav
authors.initials: S
authors.lastname: Fakan
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D004247:DNA / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D051760:Xeroderma Pigmentosum Group A Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; C086984:XPC protein, human; D004247:DNA; D045643:DNA Repair Enzymes