Evolution of epigenetic regulation in beetles (Coleoptera)

昆虫表现出显着的进化灵活性的手段，通过表观遗传调控实现。即使在甲虫（鞘翅目）的组中，一些物种依赖于CpG甲基化，而其他物种似乎没有表现出任何功能相关的CpG甲基化水平。因此，编码DNA甲基转移酶的基因（Dnmt 1和3基因）已经部分（例如，赤拟谷盗（Tribolium castaneum））或完全（例如，Dendroctonus ponderosae）在一些甲虫物种中消失。令人惊讶的是，这些Dnmt基因的敲低可以具有强烈的甚至致命的影响，即使在缺乏CpG甲基化的物种中，这表明DNMT的额外功能。另一方面，目前还不清楚哪些其他表观遗传过程可能取代了这些物种中的CpG甲基化。在脊椎动物中，组蛋白修饰在基因调控中起主要作用。组蛋白修饰系统的许多核心组分甚至从动物到植物都是保守的。组蛋白修饰和DNA甲基化两者都是全局调节剂，它们在机制上相似，即它们产生沿基因组沿着设置的标记，但在物质基础上不同。因此，本研究的主要目的有三个：（1）了解表观遗传调控系统的进化;（2）阐明DNA甲基转移酶的替代功能;（3）评估DNA甲基化和组蛋白修饰之间的相互依赖性。通过与核心项目和SPP的其他几个拟议项目的密切合作，我们将利用生物信息学，测序技术的综合力量来分析十种甲虫的表观遗传过程（甲基测序，切割和标签，RNAseq）和功能验证（RNAi）。我们的项目解决了令人惊讶的进化灵活性的东西一样重要的表观遗传调控，从而提供迫切需要的基本知识的表观遗传调控系统的进化，甚至更普遍的，超越昆虫。

Insects show a remarkable evolutionary flexibility concerning the means by which epigenetic regulation is achieved. Even within the group of beetles (Coleoptera), some species rely on CpG methylation, while other species do not seem to show any functionally relevant levels of CpG methylation. Accordingly, genes encoding DNA methyltransferases (Dnmt1 and 3 genes) have been partially (e.g., Tribolium castaneum) or completely (e.g., Dendroctonus ponderosae) lost in some beetle species. Surprisingly, knock-down of these Dnmt genes can have strong and even lethal effects, even in species lacking CpG methylation, suggesting additional functions of DNMTs. On the other hand, it is still unclear, which other epigenetic processes could have replaced CpG methylation in such species. In vertebrates, histone modification plays a major role in gene regulation. Many core components of the histone modification system are even conserved from animals to plants. Both, histone modification and DNA methylation are global regulators that are mechanistically similar in the sense that they give rise to marks being set along the genome but distinct with respect to their material basis. However, the combined mode of control may range from the mere coexistence to indispensable and rich crosstalk.Our project thus has the following three main aims: (1) Understanding the evolution of epigenetic regulation systems; (2) Elucidating alternative functions of DNA methyltransferases; (3) Assessing the mutual dependences between DNA methylation and histone modification. In close collaboration with both Core projects and several other proposed projects of this SPP, we will make use of the combined power of bioinformatics, sequencing technology to analyse epigenetic processes (Methyl-Seq, Cut&Tag, RNAseq) and functional validation (RNAi) in ten beetle species. Our project addressing the surprising evolutionary flexibility in something as crucial as epigenetic regulation will thus provide urgently needed basic knowledge of the evolution of epigenetic regulation systems even more generally, beyond insects.