Histone Lysine Methylation: Structures and Functions

描述（由申请人提供）：表观遗传调控是一个新的认识和根本重要的基因控制机制，深刻影响染色质功能。组蛋白赖氨酸和精氨酸的甲基化、去甲基化以及这些甲基标记的检测是构成表观遗传调控基础的“组蛋白密码”的组成部分。表观遗传调节因子调节哺乳动物基因组的结构、功能和通路以调节转录。已经鉴定了数百种表观遗传效应物，其中许多是催化可逆染色质修饰的酶。这些酶中的许多在同一多肽内含有不同的功能结构域，用于产生（或去除）和结合给定的甲基标记。迄今为止，这些染色质修饰酶的大多数（如果不是全部的话）可用的结构知识来自于各个结构域的结构。为了更全面地了解表观遗传调控的机制，我们需要了解这些不同的功能域是如何单独和协同工作的。该建议的中心目标是通过确定跨越几个互补表观遗传调节因子的多个结构域的结构来了解这些结构域之间的相互作用和空间关系。这些信息将帮助我们解决“写入者”和“读取者”结构域是否作用于相同的组蛋白，以及是否存在可以影响/调节其靶特异性的任何结构域间相互作用。重要的是，更广泛的主题可能会得到承认，因为几个不同的表观遗传调节器将并行研究。我在此提出四个新的具体目标，旨在回答四个相关问题。(1)赖氨酸甲基化标记的阻遏是如何传播的？(2)现有的甲基标记如何阻止组蛋白中邻近残基的修饰？(3)抑制的组蛋白标记是如何与DNA甲基化联系起来的？(4)核小体中抑制的甲基标记是如何被去除的？公共卫生相关性：表观遗传调控是一种新发现的重要基因调控机制，它深刻地影响着染色质的功能，与许多人类疾病直接相关。越来越多的染色质修饰和去修饰酶与神经退行性疾病、代谢疾病、炎症以及最显著的癌症相关。因此，针对这类新兴的基因调控酶的结构和生物化学研究可能提供一种方法，用于开发高度选择性的治疗剂，从而为治疗人类疾病提供全新的方法。在这个建议中，我们将探讨组蛋白赖氨酸修饰的动态调节（创建和删除），修饰和位置特异性相互作用，以及几个不同的表观遗传调节因子之间的生物化学串扰的问题。

DESCRIPTION (provided by applicant): Epigenetic regulation is a newly appreciated and fundamentally important set of gene control mechanisms that profoundly influences chromatin function. Histone lysine and arginine methylation, demethylation, and the detection of these methyl marks are components of a "histone code" that underlies epigenetic regulation. Epigenetic regulators modulate the structure, function, and access of the mammalian genome to regulate transcription. Hundreds of epigenetic effectors have been identified, many of which are enzymes that catalyze reversible chromatin modifications. Many of these enzymes contain distinct functional domains, within the same polypeptide, for both creating (or removing) and binding to a given methyl mark. To date, most if not all available structural knowledge of these chromatin (de)modifying enzymes comes from the structures of individual domains. To approach a more complete understanding of the mechanisms of epigenetic regulation, we need to understand how these different functional domains work, both individually and in concert. The central goal of this proposal is to understand the interactions and spatial relationships between such domains by determining structures spanning multiple domains of several complementary epigenetic regulators. Such information will help us to address whether the "writer" and "reader" domains act on the same histone, and whether there are any inter-domain interactions that can influence/regulate their target specificity. Importantly, broader themes may be recognized because several distinct epigenetic regulators will be studied in parallel. I propose here four new specific aims that are designed to answer four related questions. (1) How does a lysine methylation mark for repression spread? (2) How does an existing methyl mark prevent the modification of neighboring residues in histones? (3) How are the histone marks of repression connected to DNA methylation? (4) How are the local methyl marks of repression removed within a nucleosome? PUBLIC HEALTH RELEVANCE: Epigenetic regulation is a newly appreciated and fundamentally important set of gene control mechanisms that profoundly influences chromatin function, which has direct relevance to a large number of human diseases. An increasing number of chromatin modifying and de-modifying enzymes have been associated with neurodegenerative disorders, metabolic diseases, inflammation, and, most notably, cancer. Thus, structural and biochemical studies directed against this emerging class of gene regulatory enzymes may provide a method for the development of highly selective therapeutic agents that promise entirely novel approaches for the treatment of human diseases. In this proposal, we will explore questions of dynamic regulation (creating and removing) of histone lysine modifications, modification- and position-specific interactions, and biochemical crosstalk between modifications by several distinct epigenetic regulators.