RAG-induced DNA damage: mechanisms and responses

项目摘要 V(D)J重组事件如何参与致癌染色体的产生 一些白血病和淋巴瘤的潜在易位？许多建议已经被提出 高级。一些事件似乎涉及由碎布生成的DSB加入到由 伙伴地点的其他机制。几年前，我们提出了错误的选择 修复DSB的修复途径可能会导致异常的连接事件。我们的最新数据现在 揭示了RAG1或RAG2中的特定突变取消了途径选择，还 在体外破坏裂解后复合体的稳定性。我们的初步数据显示其中一些 RAG诱导的小鼠淋巴瘤致癌易位的突变。这些是相同的 突变与体内淋巴细胞中选择性NHEJ的增加有关。一起， 这些数据支持以下假设，我们将在拟议的实验中进行测试。 假设1：“路径选择控制”在维持基因组稳定性方面起着关键作用。 在V(D)J重组中由RAG后切割复合体维持。稳定性降低 RAG后切割复合体(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路径的可用性，便于 包括致癌染色体在内的V(D)J重组产物的异常形成 易位。假设2：取消路径选择控制允许替代NHEJ 作为一种突变修复途径出现。理解路径选择的控制和 在V(D)J重组的背景下禁用这一调控机制的后果将是 阐明了一个近30年来一直没有得到回答的问题：致癌因素是如何 发生在发育中的淋巴细胞的易位会发生吗？我们从这个过程中获得的知识 拟议的研究也可能帮助我们在其他情况下处理这一重要问题。如果， 在拟议的研究中，我们的RAG突变体解除了对途径选择的调控，使我们能够观察到 在一个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确实可以与经典的加入竞争 机械装置。这一结果将意味着对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修复情况下。

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.