Intragenic DNA methylation alters chromatin structure and elongation efficiency in mammalian cells
Intragenic DNA methylation alters chromatin structure and elongation efficiency in mammalian cells
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DOI：
10.1038/nsmb840
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发表时间：
2004-11-01
影响因子：
16.8
通讯作者：
Groudine, M
中科院分区：
文献类型：
--
作者：
Lorincz, MC;Dickerson, DR;Groudine, M
哺乳动物中的转录沉默通常与启动子甲基化有关。然而，相当数量的基因组甲基化CpG存在于转座元件中，其经常在内含子区域中发现。为了确定基因内甲基化是否影响转录效率，我们使用了Cre/loxP为基础的系统，RMCE，引入一个转基因，甲基化专门在一个区域的下游启动子，到一个特定的基因组位点。这种甲基化模式在体内得以维持，并且相对于未甲基化的对照，转基因表达明显降低。值得注意的是，RNA聚合酶II（Pol II）仅在甲基化区域被耗尽，组蛋白H3在Lys 4上被二甲基化和三甲基化以及在Lys 9和Lys 14上被乙酰化也是如此。由于甲基化区域在体内采用封闭的染色质结构，我们提出哺乳动物细胞中密集的基因内DNA甲基化启动了染色质结构的形成，从而降低了Pol II延伸的效率。
Transcriptional silencing in mammals is often associated with promoter methylation. However, a considerable number of genomic methylated CpGs exist in transposable elements, which are frequently found in intronic regions. To determine whether intragenic methylation influences transcription efficiency, we used the Cre/loxP-based system, RMCE, to introduce a transgene, methylated exclusively in a region downstream of the promoter, into a specific genomic site. This methylation pattern was maintained in vivo, and yielded a clear decrease in transgene expression relative to an unmethylated control. Notably, RNA polymerase II (Pol II) was depleted exclusively in the methylated region, as was histone H3 di- and trimethylated on Lys4 and acetylated on Lys9 and Lys14. As the methylated region adopts a closed chromatin structure in vivo, we propose that dense intragenic DNA methylation in mammalian cells initiates formation of a chromatin structure that reduces the efficiency of Pol II elongation.