Discovering the basis of the essential function of DNMT1 in wasp embryogenesis

 描述(申请人提供)：DNA甲基化在调节人类和其他真核生物的多种生物学环境中的基因组功能方面起着至关重要的作用。在人类中，甲基化异常与包括癌症在内的许多疾病有关。令人惊讶的是，甲基化所需的大部分细胞机制在主要的无脊椎动物模型系统中已经丢失，如蠕虫、线虫和果蝇。因此，这些系统中可用的强大遗传工具尚未用于DNA甲基化在发育和疾病中的基本作用的问题。黄蜂Nasonia具有无脊椎动物模型系统的许多优点(例如，小的、有序列和注释的基因组、快速发育、强大的遗传工具)。它具有完整的真核DNA甲基转移酶(DNMT1、2和3)，并且基因组在典型的CpG位点具有显著的甲基化水平。在Nasonia中有3个DNMT1同源基因(a、b和c)。当DNMT1a被RNAi击倒时，会导致胚胎死亡。这个项目旨在回答四个关于DNA甲基化和DNMT1a的作用的问题。1)早期黄蜂胚胎发育过程中DNA甲基化的动态变化？2)早期胚胎中的甲基化模式是否依赖于DNMT1a的功能？3)DNMT1a的缺失如何影响早期胚胎发育过程中基因的表达？4)依赖于DNMT1a甲基化状态的基因与DNMT1a RNAi后基因表达水平的变化是否相关？问题1和2将用全基因组亚硫酸盐序列来解决，问题3将使用RNA测序方法，问题4将使用计算方法。医学意义：Nasonia胚胎提供了一个简单、可访问和强大的模型系统，以获得对DNMT1酶和DNA甲基化的功能的基本见解，这两个主题与人类健康密切相关。在真核生物中发现的主要甲基化类型中，Nasonia似乎几乎完全使用基因体甲基化，这越来越被认为是DNA甲基化与疾病相关的一个主要方面。因此，从其他DNA甲基化模式的潜在混杂效应中分离出来，为研究基因体甲基化的重要性提供了一个特殊的机会。

 DESCRIPTION (provided by applicant): DNA methylation plays a crucial role in regulating genome function in a wide variety of biological contexts in humans and other eukaryotes. In humans, aberrations of methylation are implicated in many diseases, including cancers. Surprisingly, most of the cellular machinery required for methylation has been lost in the main invertebrate model systems, the worm C. elegans and the fly Drosophila. Thus, the powerful genetic tools available in those systems have not been brought to bear on the questions of the fundamental roles for DNA methylation in development and disease. The wasp Nasonia has many of the advantages of the invertebrate model systems (e.g., small, sequenced and annotated genome, fast development, powerful genetic tools). It possesses the full complement of eukaryotic DNA methyltransferases (DNMT1, 2, and 3), and the genome has significant levels of methylation at typical CpG sites. There are three DNMT1 paralogs (a, b, and c) in Nasonia. When DNMT1a is knocked down by RNAi, embryonic lethality results. This project aims to answer four questions about the roles of DNA methylation and DNMT1a. 1) Is DNA methylation dynamic in early wasp embryogenesis? 2) Do the patterns of methylation in the early embryo depend on DNMT1a function? 3) How does the loss of DNMT1a affect the expression of genes during early embryogenesis? 4) Are the genes whose methylation state is dependent on DNMT1a correlated with those whose mRNA expression levels change after DNMT1a RNAi? Questions 1 and 2 will be addressed with Whole Genome Bisulfite Sequence, and Question 3 will use an RNA-sequencing approach, and Question 4 will use a computational approach. Medical Relevance: The Nasonia embryo provides a simple, accessible and powerful model system to gain basic insights into the functions of DNMT1 enzymes and DNA methylation, topics that are of great relevance to human health. Of the main types of methylation found in eukaryotes, Nasonia appears to employ almost exclusively gene body methylation, which is increasingly recognized as a major aspect of the disease relevance of DNA methylation. Thus Nasonia presents a special opportunity to study the importance of gene body methylation in isolation from potential confounding effects of other modes of DNA methylation.