Distribution and repair of bipyrimidine photoproducts in solar UV-irradiated mammalian cells - Possible role of Dewar photoproducts in solar mutagenesis

Citation
D. Perdiz et al., Distribution and repair of bipyrimidine photoproducts in solar UV-irradiated mammalian cells - Possible role of Dewar photoproducts in solar mutagenesis, J BIOL CHEM, 275(35), 2000, pp. 26732-26742
Citations number
67
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
00219258 → ACNP
Volume
275
Issue
35
Year of publication
2000
Pages
26732 - 26742
Database
ISI
SICI code
0021-9258(20000901)275:35<26732:DAROBP>2.0.ZU;2-#
Abstract
In order to better understand the relative contribution of the different UV components of sunlight to solar mutagenesis, the distribution of the bipyr imidine photolesions, cyclobutane pyrimidine dimers (CPD), (6-4) photoprodu cts ((6-4)PP), and their Dewar valence photoisomers (DewarPP) was examined in Chinese hamster ovary cells irradiated with WC, UVB, or UVA radiation or simulated sunlight. The absolute amount of each type of photoproduct was m easured by using a calibrated and sensitive immune-dot-blot assay. As alrea dy established for UVC and UVB, we report the production of CPD by UVA radi ation, at a yield in accordance with the DNA absorption spectrum. At biolog ically relevant doses, DewarPP were more efficiently produced by simulated solar light than by WE (ratios of DewarPP to (6-4)PP of 1:3 and 1:8, respec tively), but were detected neither after UVA nor after UVC radiation, The c omparative rates of formation for CPD, (6-4)PP and DewarPP are 1:0.25 for U VC, 1:0.12:0.014 for UVB, and 1:0.18:0.06 for simulated sunlight. The repai r rates of these photoproducts were also studied in nucleotide excision re pair-proficient cells irradiated with UVB, UVA radiation, or simulated sunl ight. Interestingly, DewarPP were eliminated slowly, inefficiently, and at the same rate as CPD, In contrast, removal of (6-4) photoproducts was rapid and completed 24 h after exposure, Altogether, our results indicate that, in addition to CPD and (6-4)PP, DewarPP may play a role in solar cytotoxici ty and mutagenesis.