DNA helicase functions in genome maintenance

描述（由申请人提供）：内聚因子突变与出生缺陷、严重认知障碍、细胞非整倍体和癌症密切相关。目前，不同种类的内聚因子（内聚系索、沉积复合体和建立因子）的突变被认为会导致不同的发育疾病：内聚蛋白和沉积突变会导致Cornelia de Lange综合征（CdLS），而建立突变会导致Roberts综合征（RBS）。这些出生缺陷的分子基础也被认为是分开的，尽管这些多谱疾病的性质非常相似：CdLS由转录失调引起，RBS由祖细胞凋亡损失引起。我们首先发现并鉴定了第三类内聚因子- Chl1 DNA解旋酶。人类ch1 （ChlR1/DDX11）的突变导致另一种多谱发育障碍，称为华沙断裂综合征（WABS），在CdLS和RBS中都发现了许多共同的特征（认知障碍，颅/面部异常，生长迟缓，耳聋，心脏缺陷和四肢损伤）。在我们的研究过程中，我们发现Chl1不仅与建立因子Eco1相互作用，而且是内聚蛋白和内聚蛋白沉积复合物招募到DNA所必需的。由此，我们假设WABS、CdLS和RBS实际上是一种单一的疾病状态，仅通过外显率和严重程度来区分。目前，Chl1 DNA解旋酶是唯一的基础环节，通过它可以综合研究这三种疾病。尽管Chl1具有重要的（和临床）性质，但人们对其调控、作用位点或对染色质结构的影响知之甚少。在这个建议中，我们使用遗传，分子和生化方法来利用出芽酵母模型系统中的Chl1来解决与人类出生缺陷和非整倍体相关的保守途径的基本问题。具体来说，我们建议阐明Chl1在DNA复制过程中被特异性招募到DNA的机制（Specific Aim1），并确定Chl1促进内聚蛋白沉积活性的机制，重点是染色质结构（Specific Aim 2）。

DESCRIPTION (provided by applicant): Cohesion factor mutations are firmly situated at the nexus of birth defects, severe cognitive impairment, cell aneuploidy and cancer. Presently, mutations within different classes of cohesion factors (cohesin tethers, deposition complex and establishment factors) are thought to result in different developmental maladies: cohesin and deposition mutations give rise to Cornelia de Lange Syndrome (CdLS) while establishment mutations give rise to Roberts Syndrome (RBS). The molecular bases for these birth defects are also considered to be separate, despite the very similar nature of these multispectrum maladies: CdLS arising from transcription dysregulation, RBS arising from apoptotic loss of progenitor cells. We first identified and now have characterized a third class of cohesion factors - Chl1 DNA helicase. Mutations in human Chl1 (ChlR1/DDX11) leads to another multispectrum developmental disorder, termed Warsaw Breakage Syndrome (WABS) that share many features (cognitive impairment, cranio/facial abnormalities, growth retardation, deafness, heart defects and extremity impairments) found in both CdLS and RBS. In the course of our studies, we found that Chl1 both interacts with establishment factor Eco1 and is required for the recruitment to DNA of both cohesin and cohesin deposition complex. From this, we hypothesize that WABS, CdLS and RBS are in reality a single disease state differentiated only by penetrance and severity. Currently, Chl1 DNA helicase is uniquely placed as the founding link through which all three maladies can be studied in the aggregate. Despite the critical (and clinical) nature of Chl1, little is known regarding its regulation, site of action or impact on chromatin architecture. In this proposal, we use genetic, molecular and biochemical methodologies to exploit Chl1 in the budding yeast model system to address fundamental questions of conserved pathways relevant to both birth defects and aneuploidy in humans. Specifically, we propose to elucidate the mechanism through which Chl1 is recruited to DNA specifically during DNA replication (Specific Aim1) and identify the mechanism through which Chl1 promotes cohesin deposition activity, focusing on chromatin architecture (Specific Aim 2)