DNA helicase functions in genome maintenance

描述(申请人提供)：凝聚力因子突变牢固地位于出生缺陷、严重认知障碍、细胞非整倍体和癌症的连接处。目前，不同类型的凝聚力因子(粘附素锚链、沉积复合体和建立因子)内的突变被认为导致不同的发育疾病：凝聚素和沉积突变导致Cornelia de Lange综合征(CDLS)，而建立突变导致Roberts综合征(RBS)。这些出生缺陷的分子基础也被认为是独立的，尽管这些多光谱疾病的性质非常相似：CDL源于转录调控失调，RBS源于祖细胞的凋亡丧失。我们首先发现并鉴定了第三类凝聚力因子--CHL1 DNA解旋酶。人类CHL1(ChlR1/DDX11)突变导致另一种多谱系发育障碍，称为华沙破裂综合征(WABS)，该综合征在CDLS和RBS中发现许多共同特征(认知障碍、颅面部异常、生长迟缓、耳聋、心脏缺陷和肢体损害)。在我们的研究过程中，我们发现CHL1既与建立因子Eco1相互作用，也是凝集素和粘附素沉积复合体重新聚集到DNA中所必需的。由此，我们假设WABS、CDLS和RBS实际上是仅通过外显性和严重性区分的单一疾病状态。目前，CHL1 DNA解旋酶被认为是研究这三种疾病的唯一基础。尽管CHL1具有严重的(和临床的)性质，但人们对其调控、作用部位或对染色质结构的影响知之甚少。在这项建议中，我们使用遗传学、分子和生化方法在萌芽酵母模型系统中利用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。具体地说，我们建议阐明在DNA复制过程中chl1被特异性地招募到dna中的机制(特异性Aim1)，并确定chl1促进粘附素沉积活性的机制，重点是染色质结构(特异性目标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)