Effects of DNA Methylation and Chromatin State on Rates of Molecular Evolution in Insects
Effects of DNA Methylation and Chromatin State on Rates of Molecular Evolution in Insects
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DOI：
10.1534/g3.115.023499
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发表时间：
2016-02-01
影响因子：
2.6
通讯作者：
Hunt, Brendan G.
中科院分区：
文献类型：
--
作者：
Glastad, Karl M.;Goodisman, Michael A. D.;Hunt, Brendan G.
表观遗传信息因其在真核生物基因调控中的作用而受到广泛重视。然而，表观遗传信息也可以影响基因组进化。在这里，我们调查的表观遗传信息对基因序列进化的影响在两个不同的昆虫：果蝇，缺乏大量的DNA甲基化，和蚂蚁Camponotus floridanus，它具有功能性的DNA甲基化系统。我们发现，DNA甲基化与C. floridanus，表明DNA甲基化对基因进化模式的关键影响。然而，我们的数据表明，DNA甲基化和同义替换率升高之间的联系在很大程度上是通过将DNA甲基化靶向具有转录活性染色质特征的基因来解释的，而不是DNA甲基化本身的突变效应。这种现象可以解释为转录活性染色质中基因突变率的升高，或非活性染色质中基因结构约束的增加。这一结果突出了染色质结构作为昆虫基因组进化的主要表观遗传驱动力的重要性。总的来说，我们的研究证明了不同的表观遗传系统如何有助于编码序列进化速率的变化。
Epigenetic information is widely appreciated for its role in gene regulation in eukaryotic organisms. However, epigenetic information can also influence genome evolution. Here, we investigate the effects of epigenetic information on gene sequence evolution in two disparate insects: the fly Drosophila melanogaster, which lacks substantial DNA methylation, and the ant Camponotus floridanus, which possesses a functional DNA methylation system. We found that DNA methylation was positively correlated with the synonymous substitution rate in C. floridanus, suggesting a key effect of DNA methylation on patterns of gene evolution. However, our data suggest the link between DNA methylation and elevated rates of synonymous substitution was explained, in large part, by the targeting of DNA methylation to genes with signatures of transcriptionally active chromatin, rather than the mutational effect of DNA methylation itself. This phenomenon may be explained by an elevated mutation rate for genes residing in transcriptionally active chromatin, or by increased structural constraints on genes in inactive chromatin. This result highlights the importance of chromatin structure as the primary epigenetic driver of genome evolution in insects. Overall, our study demonstrates how different epigenetic systems contribute to variation in the rates of coding sequence evolution.