Structure and Pharmacologic Modulation of the Mitotic Chromosome's Central Axis

项目摘要 有丝分裂染色体的形成对于真核生物中遗传信息的传播是必不可少的。 分散的间期染色质转化为标志性的X型中期染色体 涉及三个主要事件：在纵向上形成一个中心轴(染色体的“支架”) 收缩和凝结。为了解释后两个事件，已经提出了可信的理论， 收缩是通过挤压染色质环发生的，缩合是通过 染色体物质的体积相变。相比之下，人们对它的形成知之甚少。 有丝分裂支架的存在，它的存在本身就引起了相当大的争议。直接 支架存在的证据最近来自于对中央灯丝的观察 天然有丝分裂染色体在体外进行受控扩张。这根细丝可以被解放出来， 完整，不受其染色体的限制，通过仔细的核溶解，为进一步研究提供了基础。 这项建议旨在阐明有丝分裂染色体支架的基本原理，包括其 分子组成(目标1)、其三维结构(目标2)及其与 染色质包裹它(目标1和2)。所获得的信息将提供对 有丝分裂染色体的核心，解释它的组成部分如何组装成介观比例的结构，以及这种结构如何以确保其忠实和 高效配送。所获得的知识将使我们能够更详细地研究支架组装和拆卸的机制，以及它与其他细胞相互作用的性质 成分(例如，染色质、动粒)。 该提案还寻求开发脚手架组件的化学调节剂(目标3)。作为 人们越来越了解支架及其成分在人类健康和健康中的重要作用 对于这种疾病，这些工具不仅将使对支架的进一步研究成为可能，而且还将使其能够在临床上进行药理操作。例如，凝聚素等支架成分的失调与越来越多的恶性肿瘤有关，它们在这些肿瘤中起到了作用。 一种特殊形式的基因组不稳定，称为染色体不稳定。基因组的不稳定性是一个关键 在癌细胞进化中的一个因素，促进它们逃避免疫清除和获得治疗耐药性。通过抑制导致染色体不稳定的途径，调节器 凝集素(和其他支架成分)可能会限制癌症的进化潜力 细胞。

Project Summary Mitotic chromosome formation is essential for the dissemination of genetic information in eukaryotes. The conversion of dispersed interphase chromatin into the iconic, X-shaped metaphase chromosome involves three principal events: the formation of a central axis (the chromosomal “scaffold”), lengthwise contraction, and condensation. Plausible theories have been advanced to explain the latter two events, with contraction occurring through the extrusion of chromatin loops and condensation occurring through a volume phase transition of the chromosomal material. In contrast, little is known about the formation of the mitotic scaffold, and its very existence has been the source of considerable controversy. Direct evidence for the scaffold's existence has recently come from the observation of a central filament in native mitotic chromosomes subjected to controlled expansion ex vivo. This filament could be liberated, intact, from its chromosomal confines by careful nucleolysis, providing a basis for further study. This proposal aims to elucidate basic principles of the mitotic chromosome scaffold, including its molecular composition (Aim 1), its three-dimensional architecture (Aim 2), and its interactions with the chromatin enveloping it (Aims 1 and 2). The information obtained will provide a global view of the core of the mitotic chromosome, explaining how its components assemble into a structure of mesoscopic proportions and how this structure organizes the genome in a manner ensuring its faithful and efficient distribution. The acquired knowledge will enable more detailed investigations into the mechanisms governing scaffold assembly and disassembly and the nature of its interactions with other cellular components (e.g., chromatin, kinetochores). This proposal also seeks to develop chemical modulators of scaffold assembly (Aim 3). As the scaffold and its constituents are increasingly understood to play important roles in human health and disease, such tools will not only enable further research on the scaffold but will also allow for its pharmacological manipulation in clinical contexts. Dysregulation of scaffold components such as the condensins, for instance, has been implicated in a growing number of malignancies, where they contribute to a particular form of genome instability known as chromosome instability. Genome instability is a key factor in the evolution of cancer cells, facilitating their escape from immune clearance and their acquisition of therapeutic resistance. By suppressing a pathway leading to chromosome instability, modulators of condensins (and other scaffold components) may act to limit the evolutionary potential of cancer cells.