DNA helicase and replication factor functions in genome maintenance

摘要 基本DNA-DNA相互作用的改变可导致严重的多光谱发育 疾病、细胞非整倍体、基因组不稳定和癌症。例如，DNA-DNA的不稳定 顺式结构中的相互作用(在环状dna分子的基础上)被认为会废除染色质。 DNA调控元件(增强剂、启动子、绝缘体)的紧凑和注册 部署发育转录程序。或者，DNA-DNA相互作用的不稳定 在反式中(通过染色体复制产生的姐妹染色单体之间)同时取消 高保真染色体分离所需的姐妹身份以及获得模板的途径 无错误的DNA修复所需的DNA。 粘附素复合体对于顺式和反式DNA-DNA结合都是至关重要的。因此，粘合 途径突变直接导致发育计划的放松管制，从而导致严重和 多谱系出生缺陷疾病，如罗伯茨综合征(RBS)、科妮莉亚·德朗格综合征 (CDLS)和华沙破裂综合征(WBS)，并与多种形式的 癌症、非整倍体和遗传毒性敏感性。粘附素调节的复杂分析是， 绝大多数粘附素沉积在DNA上，与核苷酸序列无关，因此 粘附素可以在细胞周期的任何部分将任何两个DNA片段捆绑在一起。我们所知道的 Scc2和Scc4异源复合体是所有粘附素沉积到DNA上所必需的 序列、系链构象或细胞周期阶段。不幸的是，人们对此知之甚少 Scc2，4对DNA的募集甚至比粘附素-分析同样受阻的发现 DNA序列可以支持Scc2，4的募集和细胞周期的任何阶段。 这份修订后的R15续订提案基于我的两个令人兴奋的发现 实验室。首先，我们最近发现CHL1 DNA解旋酶是Scc2沉积的关键调节因子。具体而言 目的1，我们将详细描述基于染色质的Scc2沉积的上游调控 我们预测将导致统一的模型，通过该模型，Scc2向DNA的募集发生在 转录、DNA复制和修复。在通过之前的R15奖励提供支持期间，我们还 成功地分离了顺式系留和反式系留中的粘附素功能(反之亦然)。 此外，我们发现，每一种都受到空间和时间上不同的机制的调节--一种 其中涉及增殖细胞核抗原。在修订后的R15续订提案的具体目标2中，我们将剖析 增殖细胞核抗原独立调节反式粘连蛋白系链的分子基础。

ABSTRACT Alterations in basic DNA-DNA interactions can result in severe multi-spectrum developmental disorders, cell aneuploidy, genome instabilities and cancer. For instance, destabilization of DNA-DNA interactions in cis (at the base of a looped DNA molecule) are thought to abolish chromatin compaction and the registration of DNA regulatory elements (enhancers, promoters, insulators) that deploy developmental transcription programs. Alternatively, destabilization of DNA-DNA interactions in trans (between sister chromatids that arise by chromosome replication) simultaneously abolishes the identity of sisters required for high fidelity chromosome segregation and also access to template DNA required for error-free DNA repair. Cohesin complexes are critical for both cis and trans DNA-DNA associations. Thus, cohesin pathway mutations directly lead to deregulation of developmental programs that result in severe and multi-spectrum birth defect maladies such as Roberts Syndrome (RBS), Cornelia de Lange Syndrome (CdLS) and Warsaw Breakage Syndrome (WBS) and also correlate tightly with numerous forms of cancer, aneuploidy and genotoxic sensitivities. Complicating analyses of cohesin regulation is that the vast majority of cohesins are deposited onto DNA, independent of nucleotide sequence, such that cohesins can tether together any two DNA segments and in any part of the cell cycle. What we know is that the Scc2 and Scc4 heterocomplex is essential for all cohesin deposition onto DNA regardless of sequence, tether conformation or cell cycle stage. Unfortunately, less is known regarding the recruitment of Scc2,4 to DNA than even cohesin – analyses similarly impeded by findings that any DNA sequence can support Scc2,4 recruitment and in any stage of the cell cycle. This revised R15 Renewal Proposal is predicated on two exciting findings emanating from my lab. First, we recently identified Chl1 DNA helicase as a key regulator of Scc2 deposition. In Specific Aim 1, we will characterize in detail the chromatin-based upstream regulation of Scc2 deposition that we predict will result in unified model through which Scc2 recruitment to DNA occurs during transcription, DNA replication and repair. During support through a previous R15 award, we also succeeded in isolating cohesin functions in cis tethering from that of trans tethering (and vice versa). Moreover, we discovered that each is regulated by spatially and temporally distinct mechanisms - one of which involves PCNA. In Specific Aim 2 of this revised R15 Renewal Proposal, we will dissect the molecular basis through which PCNA independently regulates trans cohesin tethers.