Lipinski L J, Hoehr N, Mazur S J, Dianov G L, Sentürker S, Dizdaroglu M, Bohr V A
Laboratory of Molecular Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
Nucleic Acids Res. 1999 Aug 1;27(15):3153-8. doi: 10.1093/nar/27.15.3153.
Fluorescent light (FL) has been shown to generate free radicals within cells, however, the specific chemical nature of DNA damage induced by FL has not previously been determined. Using gas chromatography/isotope dilution mass spectrometry, we have detected induction of the oxidative DNA lesions 5-hydroxycytosine (5-OH-Cyt), 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4, 6-diamino-5-formamidopyrimidine (FapyAde) in cultured cells irradiated with FL. We followed the repair of these lesions in normal and xeroderma pigmentosum group A (XP-A) cells. 5-OH-Cyt and FapyGua were repaired efficiently in normal cells within 6 h following FL exposure. XP-A cells were unable to repair these oxidative DNA base lesions. Additionally, to compare the repair of oxidative lesions induced by various sources, in vitro repair studies were performed using plasmid DNA damaged by FL, gamma-irradiation or OsO(4)treatment. Whole cell extracts from normal cells repaired damaged substrates efficiently, whereas there was little repair in XP-A extracts. Our data demon-strate defective repair of oxidative DNA base lesions in XP-A cells in vivo and in vitro.
荧光(FL)已被证明能在细胞内产生自由基,然而,此前尚未确定FL诱导的DNA损伤的具体化学性质。我们使用气相色谱/同位素稀释质谱法,检测了在用FL照射的培养细胞中氧化性DNA损伤5-羟基胞嘧啶(5-OH-Cyt)、2,6-二氨基-4-羟基-5-甲酰胺基嘧啶(FapyGua)和4,6-二氨基-5-甲酰胺基嘧啶(FapyAde)的诱导情况。我们追踪了正常细胞和A型着色性干皮病(XP-A)细胞中这些损伤的修复过程。在FL照射后6小时内,正常细胞中的5-OH-Cyt和FapyGua能有效修复。XP-A细胞无法修复这些氧化性DNA碱基损伤。此外,为了比较不同来源诱导的氧化性损伤的修复情况,我们使用经FL、γ射线照射或OsO₄处理损伤的质粒DNA进行了体外修复研究。正常细胞的全细胞提取物能有效修复受损底物,而XP-A提取物中的修复则很少。我们的数据表明,XP-A细胞在体内和体外对氧化性DNA碱基损伤的修复存在缺陷。