EFFICIENT PROTECTION AGAINST OXIDATIVE DNA DAMAGE IN CHROMATIN
EFFICIENT PROTECTION AGAINST OXIDATIVE DNA DAMAGE IN CHROMATIN
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DOI：
10.1002/mc.2940050406
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发表时间：
1992-01-01
影响因子：
4.6
通讯作者：
HANAWALT, PC
中科院分区：
文献类型：
--
作者：
LJUNGMAN, M;HANAWALT, PC
利用由核单分子层和类核样单分子层组成的体外体系作为模型染色质底物，研究了组蛋白和高阶染色质结构在保护DNA氧化损伤中的作用。这些来自人皮肤成纤维细胞的底物被通过Fe(11)-乙二胺四乙酸和抗坏血酸的Fenton反应产生的羟基自由基挑战。使用碱性解卷技术测量所产生的DNA链断裂。随着盐浓度的增加，通过对核单分子层进行预处理来顺序地从DNA中去除染色体蛋白质，显着增加了羟基自由基诱导的DNA链断裂的频率。此外，脱缩染色质中的DNA所含的DNA链断裂比裸露的超螺旋DNA少14倍，而“天然的”染色质和“浓缩的”染色质的DNA所含的染色质结构分别减少100倍和300倍，从而显著地保护DNA免受羟基自由基诱导的DNA链断裂，因此应该被认为是细胞防御DNA氧化损伤的一部分。
The role of histones and higher order chromatin structures in protecting against oxidative DNA damage was investigated using an in vitro system consisting of nuclear and nucleoid monolayers as model chromatin substrates. These substrates, derived from human skin fibroblasts, were challenged with hydroxyl radicals produced via a Fenton reaction involving Fe(ll)-ethylenediaminetetraacetic acid and ascorbic acid. The resulting DNA strand breaks were measured using the alkaline unwinding technique. The sequential removal of chromosomal proteins from the DNA by pretreating nuclear monolayers with increasing concentrations of salt dramatically increased the frequency of hydroxyl radical-induced DNA strand breaks. Furthermore, the DNA in decondensed chromatin was found to contain 14-fold fewer DNA strand breaks than naked, supercoiled DNA, whereas the DNA of "native" chromatin and "condensed" chromatin contained 100-fold and 300-fold fewer chromatin structures dramatically protects the DNA against hydroxyl radical-induced DNA strand breaks and thus should be considered part of the cellular defense against the induction of oxidative DNA damage.