The function of H3K23me3, a transgenerationally inherited heterochromatin mark

项目概要： H3 K23甲基化是一种进化上保守但研究不足的异染色质组蛋白修饰 其功能未知。在过去的一年里，我们的实验室使用C。研究H3 K23甲基化，发现 它在核RNAi中发挥作用。核RNAi是一种进化上保守的途径，其中小分子RNA干扰是一种重要的生物学机制。 干扰RNA（siRNA）引导染色质修饰和转录抑制。其保护宿主 通过表观遗传学沉默转座子和其他“非自我”DNA来控制基因组。我们已作出以下决定 发现：（1）H3 K23 me 3基因是由核RNAi诱导的，并能遗传四代。(2)组蛋白 甲基转移酶SET-32，在体外甲基化H3 K23。(3)set-32和核RNAi效应蛋白， hrde-1是核RNAi在体内诱导H3 K23 me 3所必需的。这些发现提出了新的 问题.其他负责H3 K23 me 3的组蛋白甲基转移酶是什么？的功能是什么 H3K23me3？H3 K23 me 3能在核RNAi中促进转录沉默吗？在这份提案中，我将 采取遗传学，生物化学和计算方法来解决这些问题，目标如下。（一） 生物化学表征和鉴定负责这种修饰的组蛋白甲基转移酶。（二） 使用首次在癌症中发现的显性负突变创建H3 K23 me 3的功能性敲除。（三） 研究H3 K23 me 3在核RNAi中的作用。拟议的研究，探索一个基本的，但 现代生物学的未绘制的领域，将促进我们对组蛋白密码的理解， 甲基转移酶、致癌组蛋白、RNA介导的转录沉默和RNA染色质 相互作用，这些都与人类发展和疾病有关。

PROJECT SUMMARY: H3K23 methylation is an evolutionarily conserved but understudied heterochromatic histone modification whose function is unknown. In the past year our lab used C. elegans to study H3K23 methylation and found that it plays a role in nuclear RNAi. Nuclear RNAi is an evolutionarily conserved pathway in which small interfering RNAs (siRNAs) guide chromatin modifications and transcriptional repression. It protects the host genome by epigenetically silencing transposons and other “non-self” DNA. We have made the following discoveries: (1) H3K23me3 is induced by nuclear RNAi and is inherited for four generations. (2) The histone methyltransferase SET-32, methylates H3K23 in vitro. (3) Both set-32 and the nuclear RNAi effector protein, hrde-1, are required for nuclear RNAi-induced H3K23me3 in vivo. These discoveries have raised new questions. What are the other histone methyltransferases responsible for H3K23me3? What is the function of H3K23me3? Could H3K23me3 contribute to transcriptional silencing in nuclear RNAi? In this proposal I will take genetic, biochemical, and computational approaches to address these questions in the following aims. (1) Biochemically characterize and identify the histone methyltransferase(s) responsible for this modification. (2) Create a functional knockout of H3K23me3 using a dominant negative mutation first discovered in cancer. (3) Study the function of H3K23me3 in nuclear RNAi. The proposed studies, which explore a fundamental yet unmapped territory of modern biology, will advance our understanding of the histone code, histone methyltransferases, oncogenic histones, RNA-mediated transcriptional silencing, and RNA-chromatin interaction, which are all relevant to human development and disease.