Mechanisms of R loop-mediated genome instability in Wiskott-Aldrich syndrome

摘要 DNA损伤介导的基因组不稳定性是导致人类疾病的一个因素，包括 神经变性、免疫紊乱和癌症。了解细胞如何预防和管理DNA 损伤非常严重。R环，由RNA：DNA组成的转录连接的3个核酸结构 杂合体和置换单链DNA（ssDNA），当用组蛋白H3 S10 p标记修饰时， 在其裂解成DNA双链断裂（DSB）时不稳定。目前，我们对R循环一无所知。 人类原发性免疫缺陷疾病（PIDDs），又名先天性缺陷， 免疫力使用人类Wiskott-Aldrich综合征（WAS）的PID疾病模型，我们最近发现了一种 WASp（WAS缺陷蛋白）在限制CD 4+细胞中R环介导的DNA损伤中的重要核作用 辅助性T细胞1（Th 1）淋巴细胞。这一发现开辟了一条新的研究途径， 在F-肌动蛋白聚合和基因转录中具有双重作用的核质蛋白，确保R环连接 基因组稳定性目前的建议旨在确定核信号通路和机制所涉及的 在确保健康的R环平衡，因此稳定的基因组，在人类Th细胞，以及如何他们的 WAS基因突变的破坏与免疫缺陷和临床 WAS中的表型。目的1着重于定义WASp影响细胞凋亡的基于染色质的机制。 有益（“好”）R环和有害（“坏”）R环之间的平衡，以及它们在因果关系中的影响 WAS Th 1和WAS Th 2细胞表型。目的2阐明新发现的mRNA的作用机制 WAS Th细胞中的剪接缺陷，因为它涉及R环形成和基因组不稳定性。目标3将利用主要 来自不同临床严重程度的多个WAS患者的T细胞，以建立T细胞中的R环负荷， “动态”疾病生物标志物，并确定WASp在WAS中的核-F-肌动蛋白作用的参与 表型发育从长远来看，从这些研究中获得的知识将促进发展 新的免疫学，诊断学和治疗学，用于这种PID和其他R环介导的免疫学 紊乱

ABSTRACT DNA damage-mediated genome instability is a contributing factor in the causation of human diseases, including neurodegeneration, immunological disorders, and cancer. Understanding how cells prevent and manage DNA damage is highly significant. R loop, a transcription-linked 3 nucleic-acid structure consisting of a RNA:DNA hybrid and a displaced single-strand DNA (ssDNA), when decorated with histone H3S10p mark causes genomic instability upon its cleavage into DNA double strand breaks (DSBs). Currently, nothing is known about R loop dysfunction in the causation of human primary immunodeficiency disorders (PIDDs), aka, inborn errors of immunity. Using a PID disease model of human Wiskott-Aldrich syndrome (WAS), we recently discovered an essential nuclear role of WASp, the protein deficient in WAS, in limiting R loop-mediated DNA damage in CD4+ T helper 1 (Th1) lymphocytes. This discovery has opened up a new avenue of research into how WASp, a nucleocytoplasmic protein with dual-roles in F-actin polymerization and gene transcription, ensures R loop-linked genome stability. The current proposal seeks to define the nuclear signaling pathways and mechanisms involved in ensuring a healthy R loop balance, and therefore a stable genome, in human Th cells, and how their disruptions by WAS gene mutations is causally-linked to the development of immune deficiency and clinical phenotypes in WAS. Aim 1 focuses on defining chromatin-based mechanisms by which WASp influences the balance between beneficial (“good”) R loops and deleterious (“bad”) R loops, and their effects in the causation of WAS Th1 and WAS Th2 cellular phenotypes. Aim 2 will clarify the mechanism of the newly identified mRNA splicing defect in WAS Th cells as it relates to R loop formation and genome instability. Aim 3 will utilize primary T cells from multiple WAS patients of differing clinical severities to establish R loop load in the T cells as a “dynamic” disease biomarker, and to define the involvement of nuclear-F-actin effects of WASp in WAS phenotype development. In the long-term, the knowledge gained from these studies will foster the development of novel prognostics, diagnostics, and therapeutics for this PID and other R loop-mediated immunological disorders.