Comparative analysis of DNA methylation patterns in transgenic Drosophila overexpressing mouse DNA methyltransferases
Comparative analysis of DNA methylation patterns in transgenic Drosophila overexpressing mouse DNA methyltransferases
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DOI：
10.1042/bj20031567
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发表时间：
2004-03-15
影响因子：
4.1
通讯作者：
Lyko, F
中科院分区：
文献类型：
--
作者：
Mund, C;Musch, T;Lyko, F
DNA甲基转移酶(DNMT)介导真核基因组的表观遗传修饰。哺乳动物的DNA甲基化模式是通过Dnmt蛋白Dnmt1、DNMT3a和Dnmt3b之间的协同作用来建立和维持的。由于它们同时存在于哺乳动物细胞中，单个DNMT的活性尚未确定。这包括第四种推定的DNMT，即DNMT2，在以前的检测中未能发现任何活性。我们现在已经建立了转基因果蝇品系，允许所有已知的小鼠DNMT单独过表达。基因组胞嘧啶甲基化水平的定量分析表明，从头开始的甲基转移酶DNMT3a和Dnmt3b具有很强的硬脑膜活性。此外，我们还检测到了DNMT2的微弱但显著的活性。随后的基因组测序甲基化途径分析表明，DNMT3酶以进程方式优先甲基化CpG二核苷酸，而DNMT2在非CpG二核苷酸背景下甲基化分离的胞嘧啶残基。我们的结果允许直接比较哺乳动物DNMT的活性，并表明这些酶具有显著的功能专一性。
DNA methyltransferases (Dnmts) mediate the epigenetic modification of eukaryotic genomes. Mammalian DNA methylation patterns are established and maintained by co-operative interactions among the Dnmt proteins Dnmt1, Dnmt3a and Dnmt3b. Owing to their simultaneous presence in mammalian cells, the activities of individual Dnmt have not yet been determined. This includes a fourth putative Dnmt, namely Dnmt2, which has failed to reveal any activity in previous assays. We have now established transgenic Drosophila strains that allow for individual overexpression of all known mouse Dnmts. Quantitative analysis of genomic cytosine methylation levels demonstrated a robust Dural activity for the de novo methyltransferases Dnmt3a and Dnmt3b. In addition, we also detected a weak but significant activity for Dnmt2. Subsequent methylation tract analysis by genomic bisulphite sequencing revealed that Dnmt3 enzymes preferentially methylated CpG dinucleotides in a processive manner, whereas Dnmt2 methylated isolated cytosine residues in a non-CpG dinucleotide context. Our results allow a direct comparison of the activities of mammalian Dnmts and suggest a significant functional specialization of these enzymes.