Non-homologous end joining induced alterations in DNA methylation: A source of permanent epigenetic change.
Non-homologous end joining induced alterations in DNA methylation: A source of permanent epigenetic change.
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DOI：
10.18632/oncotarget.16122
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发表时间：
2017-06-20
期刊：
影响因子：
--
通讯作者：
Masternak MM
中科院分区：
文献类型：
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作者：
Allen B;Pezone A;Porcellini A;Muller MT;Masternak MM
除了基因突变，表观遗传修正在癌症的发生和发展中起着重要作用；具体地说，不适当的DNA甲基化或CpG残基去甲基化可能会改变促进肿瘤发生的基因的表达。我们推测DNA修复，特别是通过非同源末端连接(NHEJ)修复DNA双链断裂(DSB)可能在这一过程中发挥作用。使用插入HeLa细胞基因组的GFP报告系统，我们能够诱导靶向DNA损伤，使细胞在成功经历NHEJ修复后表达WT GFP。这些GFP+细胞被分成两种表达类型，一种是强势表达(Bright)，另一种是低表达(Dim)。使用DNA去甲基化药物(AzadC)，我们证明了不同的GFP表达水平是由于断裂部位两侧CPGS区域不同的甲基化状态所致。对已排序的Bright和Dim群体中这一区域的深度测序分析揭示了一组不同的表观等位基因，这些等位基因在NHEJ修复后显示出DNA甲基化的模式。这些模式在分别是低甲基化和高甲基化的Bright和Dim细胞之间，以及修复后的群体和原始的未切割细胞之间有所不同。这些数据表明，NHEJ修复促进了修复基因中甲基化格局的重写，阐明了癌细胞中甲基化模式改变的潜在来源，并了解了发生这种变化的机制可以为防止这一过程促进肿瘤发生提供新的治疗靶点。
In addition to genetic mutations, epigenetic revision plays a major role in the development and progression of cancer; specifically, inappropriate DNA methylation or demethylation of CpG residues may alter the expression of genes that promote tumorigenesis. We hypothesize that DNA repair, specifically the repair of DNA double strand breaks (DSB) by Non-Homologous End Joining (NHEJ) may play a role in this process. Using a GFP reporter system inserted into the genome of HeLa cells, we are able to induce targeted DNA damage that enables the cells, after successfully undergoing NHEJ repair, to express WT GFP. These GFP+ cells were segregated into two expression classes, one with robust expression (Bright) and the other with reduced expression (Dim). Using a DNA hypomethylating drug (AzadC) we demonstrated that the different GFP expression levels was due to differential methylation statuses of CpGs in regions on either side of the break site. Deep sequencing analysis of this area in sorted Bright and Dim populations revealed a collection of different epi-alleles that display patterns of DNA methylation following repair by NHEJ. These patterns differ between Bright and Dim cells which are hypo- and hypermethylated, respectively, and between the post-repair populations and the original, uncut cells. These data suggest that NHEJ repair facilitates a rewrite of the methylation landscape in repaired genes, elucidating a potential source for the altered methylation patterns seen in cancer cells, and understanding the mechanism by which this occurs could provide new therapeutic targets for preventing this process from contributing to tumorigenesis.