Tsurudome Y, Hirano T, Kamiya H, Yamaguchi R, Asami S, Itoh H, Kasai H
Department of Environmental Oncology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Mutat Res. 1998 Aug 7;408(2):121-7. doi: 10.1016/s0921-8777(98)00025-1.
Oxygen radicals are known to play a role in causing cellular DNA damage, which is involved in carcinogenesis. 8-Hydroxyguanine (8-OH-Gua) is a major form of oxidative DNA damage and is known as a useful marker of DNA oxidation. Recently, we found another type of oxidative DNA damage, 2-hydroxyadenine (2-OH-Ade), which has a mutation frequency comparable to that of 8-OH-Gua. We compared the repair activities for two types of oxidative DNA damage, 8-OH-Gua and 2-OH-Ade, in 7-week-old male Sprague-Dawley (SD) rat organs. The repair activities were measured by an endonuclease nicking assay using 22 mer [32P]-end-labeled double-stranded DNA substrates, which contained either 8-OH-Gua (opposite C) or 2-OH-Ade (opposite T or C). In all of the SD rat organs we studied, the nicking activity for 2-OH-Ade was not detected, while that for 8-OH-Gua was clearly detected with the same conditions. Moreover, the 2-OH-Ade nicking activity was not induced in Wistar rat kidney extracts prepared after ferric nitrilotriacetate (Fe-NTA) treatment, which is known to increase 8-OH-Gua repair activity. These results suggest that 2-OH-Ade might not be repaired by the glycosylase type mechanism in mammalian cells.
已知氧自由基在导致细胞DNA损伤中起作用，而细胞DNA损伤与致癌作用有关。8-羟基鸟嘌呤（8-OH-Gua）是氧化性DNA损伤的主要形式，是一种有用的DNA氧化标志物。最近，我们发现了另一种氧化性DNA损伤类型，2-羟基腺嘌呤（2-OH-Ade），其突变频率与8-OH-Gua相当。我们比较了7周龄雄性斯普拉格-道利（SD）大鼠器官中两种氧化性DNA损伤类型，即8-OH-Gua和2-OH-Ade的修复活性。使用22聚体[32P]末端标记的双链DNA底物通过内切酶切口测定法测量修复活性，该底物含有8-OH-Gua（与C相对）或2-OH-Ade（与T或C相对）。在我们研究的所有SD大鼠器官中，未检测到2-OH-Ade的切口活性，而在相同条件下清楚地检测到了8-OH-Gua的切口活性。此外，在次氮基三乙酸铁（Fe-NTA）处理后制备的Wistar大鼠肾提取物中未诱导出2-OH-Ade切口活性，已知Fe-NTA处理可增加8-OH-Gua修复活性。这些结果表明，2-OH-Ade在哺乳动物细胞中可能不会通过糖基化酶类型的机制进行修复。
