The function of H3K23me3, a transgenerationally inherited heterochromatin mark

项目总结： H3K23甲基化是一种进化上保守但研究较少的异染色组蛋白修饰 其功能尚不清楚。在过去的一年里，我们的实验室使用线虫来研究H3K23甲基化，发现 它在核RNAi中发挥作用。核RNAi是一条进化上保守的途径，其中小分子 干扰RNA(SiRNAs)引导染色质修饰和转录抑制。它可以保护主机 通过表观遗传沉默转座子和其他“非我”DNA。我们做了以下工作 发现：(1)H3K23me3由核RNAi诱导，遗传4代。(2)组蛋白 甲基转移酶SET-32，体外甲基化H3K23。(3)SET-32和核RNAi效应蛋白， Hrde-1是RNAi在体内诱导H3K23me3核表达所必需的。这些发现提出了新的 问题。H3K23me3的其他组蛋白甲基转移酶是什么？的功能是什么？ H3K23me3？H3K23me3是否有助于核RNAi中的转录沉默？在这项提议中，我将 采取遗传学、生物化学和计算方法来解决以下目标中的这些问题。(1) 生化表征和鉴定负责这种修饰的组蛋白甲基转移酶(S)。(2) 使用首次在癌症中发现的显性负突变创建H3K23me3的功能性敲除。(3) 研究H3K23me3在核RNAi中的作用。拟议的研究，探索了一个基础的 现代生物学的未知领域，将推进我们对组蛋白密码、组蛋白的理解 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.