Gene silencing induced by oxidative DNA base damage: association with local decrease of histone H4 acetylation in the promoter region
Gene silencing induced by oxidative DNA base damage: association with local decrease of histone H4 acetylation in the promoter region
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DOI：
10.1093/nar/gkq170
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发表时间：
2010-07-01
影响因子：
14.9
通讯作者：
Epe, Bernd
中科院分区：
文献类型：
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作者：
Khobta, Andriy;Anderhub, Simon;Epe, Bernd
氧化的DNA碱基，特别是7,8-二氢-8-氧鸟嘌呤（8-oxoG），是细胞内源性产生的，是致癌突变的原因，可能干扰基因表达。我们发现，氧化损伤的质粒DNA在传递到人类宿主细胞后，不仅由于在转染细胞中的保留减少，而且由于受损的报告基因的选择性沉默。为了测试基因沉默是否与染色质结构的特定变化有关，我们确定了启动子区域和下游转录DNA中与转录激活（乙酰化组蛋白H3和H4）或抑制（甲基化组蛋白H3和组蛋白H1的K9和K27）相关的组蛋白修饰水平。在受损基因的近端启动子区域发现组蛋白H4的乙酰化特异性降低了25%，而其他测试的染色质成分的微小定量变化不能证明是显著的。用组蛋白去乙酰化酶抑制剂trichostatin A治疗，部分恢复了受损DNA的表达，这表明组蛋白乙酰化的变化与持续的基因抑制之间存在因果关系。基于这些发现，我们提出氧化损伤DNA的沉默可能发生在染色质介导的机制中。
Oxidized DNA bases, particularly 7,8-dihydro-8-oxoguanine (8-oxoG), are endogenously generated in cells, being a cause of carcinogenic mutations and possibly interfering with gene expression. We found that expression of an oxidatively damaged plasmid DNA is impaired after delivery into human host cells not only due to decreased retention in the transfected cells, but also due to selective silencing of the damaged reporter gene. To test whether the gene silencing was associated with a specific change of the chromatin structure, we determined the levels of histone modifications related to transcriptional activation (acetylated histones H3 and H4) or repression (methylated K9 and K27 of the histone H3, and histone H1) in the promoter region and in the downstream transcribed DNA. Acetylation of histone H4 was found to be specifically decreased by 25% in the proximal promoter region of the damaged gene, while minor quantitative changes in other tested chromatin components could not be proven as significant. Treatment with an inhibitor of histone deacetylases, trichostatin A, partially restored expression of the damaged DNA, suggesting a causal connection between the changes of histone acetylation and persistent gene repression. Based on these findings, we propose that silencing of the oxidatively damaged DNA may occur in a chromatin-mediated mechanism.