title: Heterogeneity of dimer excision in young and senescent human dermal fibroblasts.
abstract: We have examined the relationship between nucleotide excision of the main UV-induced photoproduct, the cyclobutane pyrimidine dimer and in vitro cellular senescence. An in situ semiquantitative immunocytochemical assay has demonstrated that, following a UV-C dose of 15 J m-2, young human dermal fibroblasts maintained in a high level of serum are more efficient than senescent fibroblasts in the removal of dimers. However, in G0-arrested cultures (serum-starved), young fibroblasts are compromised in their ability to remove dimers and are significantly less efficient than senescent cells in this process. Supplementation of the culture medium with 0.1 mm deoxyribonucleosides enhances the removal of dimers in both young and senescent fibroblasts in proliferating or serum-starved cells. These data indicate that overall there is a modest but significant reduction in nucleotide excision of dimer photoproducts in cells as they age in vitro. In addition, G0-arrested young cells exhibit reduced removal of dimers, although this can be complemented by deoxyribonucleoside addition. In addition, this in situ assay has revealed heterogeneity in both susceptibility to UV-C-induced damage and excision. Overall, we provide evidence of reduced UV-induced damage excision in senescent compared with young fibroblasts, and demonstrate modulation of these processes in young and senescent cells under specific growth conditions.
authors.affiliation: Cell and Chromosome Biology Group, Brunel Institute of Cancer Genetics and Pharmacogenetics, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Middlesex, UB8 3PH, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Boyle
authors.forename: Ian R
authors.initials: IR
authors.lastname: Kill
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Parris
mesh_terms: D015415:Biomarkers; D002478:Cells, Cultured; D016922:Cellular Senescence; D003470:Culture Media / Q000737:chemistry; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003853:Deoxyribonucleosides / Q000378:metabolism; D020405:Dermis / Q000166:cytology*; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D006801:Humans; D008297:Male; D011740:Pyrimidine Dimers; D015203:Reproducibility of Results; D014466:Ultraviolet Rays; D051760:Xeroderma Pigmentosum Group A Protein
chemical_list: D015415:Biomarkers; D003470:Culture Media; D004268:DNA-Binding Proteins; D003853:Deoxyribonucleosides; D011740:Pyrimidine Dimers; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein