title: Detrimental effects of UV-B radiation in a xeroderma pigmentosum-variant cell line.
abstract: DNA polymerase η (pol η), of the Y-family, is well known for its in vitro DNA lesion bypass ability. The most well-characterized lesion bypassed by this polymerase is the cyclobutane pyrimidine dimer (CPD) caused by ultraviolet (UV) light. Historically, cellular and whole-animal models for this area of research have been conducted using UV-C (λ=100-280 nm) owing to its ability to generate large quantities of CPDs and also the more structurally distorting 6-4 photoproduct. Although UV-C is useful as a laboratory tool, exposure to these wavelengths is generally very low owing to being filtered by stratospheric ozone. We are interested in the more environmentally relevant wavelength range of UV-B (λ=280-315 nm) for its role in causing cytotoxicity and mutagenesis. We evaluated these endpoints in both a normal human fibroblast control line and a Xeroderma pigmentosum variant cell line in which the POLH gene contains a truncating point mutation, leading to a nonfunctional polymerase. We demonstrate that UV-B has similar but less striking effects compared to UV-C in both its cytotoxic and its mutagenic effects. Analysis of the mutation spectra after a single dose of UV-B shows that a majority of mutations can be attributed to mutagenic bypass of dipyrimidine sequences. However, we do note additional types of mutations with UV-B that are not previously reported after UV-C exposure. We speculate that these differences are attributed to a change in the spectra of photoproduct lesions rather than other lesions caused by oxidative stress.
authors.affiliation: Department of Biological Sciences, Environmental and Molecular Toxicology Program, North Carolina State University, Raleigh, North Carolina.
authors.forename: Kimberly N
authors.initials: KN
authors.lastname: Herman
authors.forename: Shannon
authors.initials: S
authors.lastname: Toffton
authors.forename: Scott D
authors.initials: SD
authors.lastname: McCulloch
mesh_terms: D002110:Caffeine / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects*; D002478:Cells, Cultured; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D016296:Mutagenesis; D009154:Mutation / Q000235:genetics*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014983:Xeroderma Pigmentosum; D000099270:Y-Family DNA Polymerases
chemical_list: D002110:Caffeine; D000697:Central Nervous System Stimulants; D004259:DNA-Directed DNA Polymerase; D007041:Hypoxanthine Phosphoribosyltransferase; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases
keywords: DNA damage; DNA polymerase η; mutagenesis; translesion synthesis; ultraviolet radiation