Molecular Basis of Coats Plus Disease

Coats+综合征是一种罕见的危及生命的遗传性疾病，其特征是多系统 导致双侧渗出性视网膜病变、视网膜毛细血管扩张、生长迟缓 颅内钙化、骨骼异常、胃肠道血管扩张和常见的早衰 病理特征像许多其他发育障碍一样，Coats plus是由基因缺陷引起的 参与维护全球基因组完整性。具体地说，它是由基因组中的功能丧失突变引起的。 人CTC 1/STN 1/TEN 1（CST）复合物，其是优先结合富含G的ssDNA的三聚体复合物 或ss-ds DNA连接，并且对于防止由复制扰动引起的基因组不稳定性至关重要。我们 希望通过以下方式帮助更好地了解疾病发展和设计有效的治疗策略， 研究在复制压力下基因组稳定性的机制。为了应对叉子失速， 信号级联激活多种途径，包括叉逆转、跨损伤合成、再引发 停止的位点的下游，以及休眠的起始点激发以拯救停止的复制。这些途径的活动 需要严格控制以确保复制的保真度。这个提案的目的是描绘一个新的 信号通路，阐明它如何调节蛋白质的相互作用和招聘 在失速的叉子，并了解调节再引发途径的机制。在目标1中，我们假设， 钙依赖性信号通路磷酸化STN 1以激活停滞分叉处的CST， 稳定的分叉。我们将阐明这一新的信号通路，并确定这一通路如何 拮抗不定期的新生链DNA降解并调节叉保护。在目标2中，我们将 研究这种信号通路如何调节单链DNA结合蛋白在分叉处的相互作用， 其他叉结合蛋白。在目标3中，我们将研究限制过度再启动的机制， 防止ssDNA缺口形成和基因组不稳定性。我们将结合联合收割机高灵敏度的细胞分析， 单分子和强大的生化分析，以实现拟议的研究目标。我们预计 我们的努力将确定新的因素和途径调节救援停滞的复制和 保持基因组的稳定性。

The Coats plus syndrome is a rare and life-threatening genetic disorder characterized by multi-system developmental defects that lead to bilateral exudative retinopathy, retinal telangiectasias, growth retardation, intracranial calcifications, bone abnormalities, gastrointestinal vascular ectasias, and common early-aging pathological features. Like many other developmental disorders, Coats plus is caused by defects in genes involved in maintaining global genome integrity. Specifically, it is caused by loss-of-function mutations in the human CTC1/STN1/TEN1 (CST) complex, which is a trimeric complex that preferentially binds to G-rich ssDNA or ss-ds DNA junctions and is critical for preventing genome instabilities arising from replication perturbation. We hope to aid in better understanding of disease development and designing of effective therapeutic strategies by investigating the mechanisms governing genome stability under replication stress. In response to fork stalling, signaling cascades activate multiple pathways including fork reversal, translesion synthesis, repriming downstream of stalled sites, and dormant origin firing to rescue stalled replication. Activities of these pathways need to be tightly regulated to ensure replication fidelity. The objectives of this proposal is to delineate a novel signaling pathway in response to replication stress, elucidate how it regulates protein interplays and recruitment at stalled forks, and understand the mechanism regulating the repriming pathway. In Aim 1, we hypothesize that a calcium-dependent signaling pathway phosphorylates STN1 to activate CST at stalled forks to protect the stability of stalled forks. We will elucidate this new signaling pathway and determine how this pathway antagonizes unscheduled nascent strand DNA degradation and regulates fork protection. In Aim 2, we will investigate how this signaling pathway regulates the interplay of single-strand DNA binding proteins at forks and other fork binding proteins. In Aim 3, we will investigate the mechanism for restricting excessive repriming to prevent ssDNA gap formation and genome instability. We will combine highly sensitive cell-based analyses, single-molecule and powerful biochemical assays to accomplish the goals of the proposed research. We expect that our efforts will identify new factors and pathways regulating the rescue of stalled replication and the preservation of genome stability.