RAG-induced DNA damage: mechanisms and responses

项目概要 V(D)J 重组事件如何参与致癌染色体的生成 某些白血病和淋巴瘤的易位？许多提案已被 先进的。一些事件似乎涉及将 RAG 生成的 DSB 加入到由 伙伴基因座的其他机制。几年前，我们提出错误的选择 修复 DSB 的途径可能会导致异常的连接事件。我们现在的最新数据 表明 RAG1 或 RAG2 中的特定突变会取消通路选择，并且 体外破坏切割后复合物的稳定性。我们的初步数据表明其中一些 RAG 诱导的小鼠淋巴瘤致癌易位突变。这些相同的 突变与体内淋巴细胞中替代 NHEJ 的增加有关。在一起， 这些数据支持以下假设，我们将在拟议的实验中对其进行测试。 假设1：“通路选择控制”在维持基因组稳定性中发挥着关键作用，并且 由 RAG 裂解后复合物维持 V(D)J 重组。稳定性下降 RAG 裂解后复合物（由多种原因中的任何一种引起）允许增加 编码和/或信号末端对不适当的连接途径的可用性，促进 异常 V(D)J 重组产物的形成，包括致癌染色体 易位。假设 2：废除通路选择控制允许替代 NHEJ 作为一种诱变修复途径出现。了解路径选择的控制和 在 V(D)J 重组背景下禁用该调节机制的后果将 阐明了一个近 30 年来一直悬而未决的问题：致癌物质是如何产生的？ 发育中的淋巴细胞发生易位吗？我们从中获得的知识 拟议的研究也可能帮助我们在其他情况下解决这个重要问题。如果， 在拟议的研究中，我们的 RAG 突变体解除了通路选择的管制，使我们能够观察到 在完整的经典途径的背景下频繁的致癌重排，我们将 能够确定替代 NHEJ 确实可以与经典连接竞争 机制。这一结果意味着路径选择的控制是由某些人强加的。 机制，在其他不涉及 RAG 蛋白的 DSB 修复情况中。

Project Summary How are V(D)J recombination events involved in generating oncogenic chromosome translocations underlying some leukemias and lymphomas? Many proposals have been advanced. Some events appear to involve joining of RAG-generated DSBs to breaks made by other mechanisms at the partner loci. A few years ago, we proposed that errors the choice of repair pathway to heal the DSB could lead to aberrant joining events. Our recent data now reveal that specific mutations in either RAG1 or RAG2 abrogate pathway choice and also destabilize the post-cleavage complex in vitro. Our preliminary data implicate some of these mutations in RAG-induced oncogenic translocations in murine lymphomas. These same mutations are associated with increased alternative NHEJ in lymphocytes in vivo. Together, these data support the following hypotheses, which we will test in the proposed experiments. Hypothesis 1: "Pathway choice control" plays a critical role in maintaining genomic stability, and is maintained in V(D)J recombination by the RAG post-cleavage complex. Decreased stability of the RAG postcleavage complex (resulting from any of a number of causes) allows increased availability of the coding and/or signal ends to inappropriate joining pathways, facilitating formation of aberrant V(D)J recombination products, including oncogenic chromosome translocations. Hypothesis 2: Abrogating pathway choice control allows alternative NHEJ to emerge as a mutagenic repair pathway. Understanding control of pathway choice and the consequences of disabling this regulatory mechanism in the context of V(D)J recombination will illuminate a question that has remained unanswered for almost 30 years: how do the oncogenic translocations that occur in developing lymphocytes arise? The knowledge we gain from the proposed studies is also likely to help us approach this important question in other contexts. If, in the proposed studies, our RAG mutants which deregulate pathway choice allow us to observe frequent oncogenic rearrangements in the context of an intact classical pathway, we will be able to establish that alternative NHEJ can indeed compete with the classical joining mechanisms. This result would imply that control of pathway choice is imposed, by some mechanism, in other DSB repair situations that do not involve the RAG proteins.