MAPPING OF CHROMATIN BORDER ELEMENTS IN THE MAMMALIAN GENOME

哺乳动物的染色体被组织成一系列可超盘绕的环 结构域的长度约为100千碱基，每个结构域的末端都连接到一个 核矩阵。这些环或染色质结构域是功能单位 转录能力，因为每个独立的结构域都可以 组装成活性染色质或非活性染色质。我们的长- 术语目标是了解染色质结构域的功能和 组成它们的元素，这样我们就可以获得完整的 了解基因表达的调节以及它可能是如何 用于基础研究、医学(基因和癌症治疗)和 商业(药品生产和交付)应用。 大多数研究都集中在邻近区域的调控因素上。 基因，包括启动子和增强子元件，结合蛋白 这些，以及启动子周围的DNA修饰。现在，它是丰富的 显然，关键的控制元素往往多达数百个 在我们有一个结构定义的单位内的一个基因的千碱基 称为染色质结构域。很少有这样的功能域被 在任何细节上都有特点，当他们有了方法一般 通常是寻找一种或几种类型的监管要素。 要彻底理解，我们需要在 细节，使用一系列方法来识别所有潜在的 这些领域中的重要监管要素。尽管矩阵 附着区、复制源和绝缘体，其能够 抑制一个结构域中的启动子和增强子之间的相互作用 在另一种情况下，可能在某些情况下，这些元素可能仍然是 功能上不同的，不一定重叠的。它只是通过 在我们希望做出的一些案例中列出了所有这样的元素 这些重要的区别。域的详细映射将允许 美国确定这些领域的关键监管要素，在 为将来的研究做准备，在这些研究中，我们计划在 实验系统，或删除或更改它们。我们最初的映射是 在这里提出不仅让我们能够理解和操纵这些 更好的特定领域，但有望揭示一般功能 也将加快我们绘制其他领域地图的能力。

Mammalian chromosomes are organized as a series of supercoilable looped domains about 100 kilobases in length, each tethered at its end to a nuclear matrix. These loops or chromatin domains are the functional units of transcriptional competence in that each independent domain can be assembled either as active chromatin or as inactive chromatin. Our long- term objective is to understand the function of chromatin domains and the elements that comprise them so that we may acquire a complete understanding of the regulation of gene expression and how it may be manipulated for basic research, medical (gene and cancer therapy) and commercial (drug production and delivery) applications. Most studies have focused on regulatory elements in the immediate vicinity of genes, including promoter and enhancer elements, proteins binding to these, and DNA modification around the promoter. It is now abundantly clear that crucial control elements often lie as much as several hundred kilobases from a gene within a structurally-defined unit which we have referred to as the chromatin domain. Few such functional domains have been characterized in any detail, and when they have the approach has generally has generally been a search for one or a few types of regulatory elements. A thorough understanding requires that we map a number of domains in detail, using a battery of methods to identify all of the potentially important regulatory elements in those domains. Although a matrix attachment region, a replication origin and an insulator, capable of dampening the interaction between a promoter in one domain and an enhancer in another, could co-occur in some instances, these elements may still be functionally distinct and not necessarily overlapping. It is only by mapping out all such elements in a number of cases that we expect to make these important distinctions. The detailed mapping of domains will allow us to identify the crucial regulatory elements in those domains, in preparation for future studies in which we plan to test these elements in experimental systems, or to delete or alter them. The initial mapping we propose here will not only allow us to understand and manipulate these particular domains better, but will hopefully reveal general features that will accelerate our ability to map other domains as well.