Role of ATM and RAG in maintaining genome stability during Tcra/d rearrangement.

描述（由申请人提供）：B细胞和T细胞表达识别几乎无限种抗原的受体。这些受体的多样性是通过称为V(D)J重组的过程产生的。这涉及到抗原受体基因的重复切割和修复，这些基因分散在几个不同的染色体上。重组是精心调节的，发生在不同的染色体位点在一个特定的序列。这通常不会发生意外，但有时也会发生错误。已知非同源末端连接（NHEJ）组分和DNA损伤反应途径的缺陷易导致异常的V(D)J重排事件，从而导致白血病和淋巴瘤。在很大程度上，损伤的范围将取决于每个因素对rag介导的双链断裂修复的贡献。在这种情况下，个体修复和损伤反应因子的作用已经得到了广泛的研究，但除此之外，对于这些因子是否在调节RAG酶活性或抗原受体位点和周围基因的可及性中发挥作用知之甚少，在一个等位基因上引入RAG介导的断裂后停止切割。本基金概述的工作将导致对程序性DNA断裂如何以受控方式引入以保护V(D)J重组期间基因组稳定性的更详细和机制的理解。我们的目标是观察发育中的T细胞基因组的3D组织，以识别与重组细胞中Tcra/d密切相关的“危险”候选细胞。此外，我们将确定亲密关系是否通过活跃转录基因的环出和转录工厂的聚集来培养，这些转录工厂可以富集RAG蛋白。核组织和基因活性的联合分析（已知是RAG靶向的重要决定因素）将为我们解开单个修复因子的作用提供一个起点。重要的是，该分析将使我们能够将已知的致癌易位事件置于全球背景下，以便我们能够开始理解为什么特定基因被靶向并与染色体重排中的Tcra/d结合。)

DESCRIPTION (provided by applicant): B and T cells express receptors that recognize an almost infinite variety of antigens. The diversity of these receptors is generated through a process known as V(D)J recombination. This involves repeated cleavage and repair of antigen receptor genes, which are scattered across several different chromosomes. Recombination is carefully regulated and occurs at different chromosomal loci in a specific sequence. This normally proceeds without mishap, but mistakes do sometimes occur. Deficiencies in components of the nonhomologous end joining (NHEJ) and DNA damage response pathways are known to predispose to aberrant V(D)J rearrangement events that can lead to leukemias and lymphomas. In large part, the spectrum of damage will depend on the contribution of each factor to the repair of RAG-mediated double strand breaks. The effects of individual repair and damage response factors in this context have been extensively studied, but beyond this, little is known about whether any of these factors have a role in regulating RAG enzymatic activity or the accessibility of the antigen receptor loci and surrounding genes to halt cleavage after RAG-mediated breaks are introduced on one allele. The work outlined in this grant will lead to a more detailed and mechanistic understanding of how programmed DNA breaks are introduced in a controlled manner to protect genome stability during V(D)J recombination. We aim to look at the 3D organization of the genome in developing T cells to identify 'at risk' candidates that are closely associated with Tcra/d in cells where they are being recombined. Further, we will determine whether intimate relationships are fostered by looping out of actively transcribed genes and congregation in transcription factories that could be enriched for RAG proteins. The combined analyses of nuclear organization and gene activity (which is known to be an important determinant of RAG targeting) will provide us with a starting point from which to unravel the effects of individual repair factors. Importantly, this analysis will allow us to put known oncogenc translocation events into a global context so that we can begin to understand why particular genes are targeted and join with Tcra/d in chromosomal rearrangements. )