ATM FUNCTION DURING V(D)J RECOMBINATION

V(D)J 重组期间的 ATM 功能

• 批准号: 8386917
• 负责人: BARRY P SLECKMAN
• 金额: $ 35.01万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-12-02 至 2013-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8386917
• 关键词: Antigen Receptors; Ataxia Telangiectasia; Biological Assay; Cell Cycle Checkpoint; Cell Line; Cells; Chromosomal translocation; Code; Complex; DNA; DNA Damage; DNA Double Strand Break; Defect; Disease; Double Strand Break Repair; Genes; Genome Stability; Goals; Health; Hybrids; Incidence; Joints; Lead; Lymphocyte; Lymphocyte antigen; Lymphoid; Lymphopenia; Mediating; Mus; Mutation; Nonhomologous DNA End Joining; Pathway interactions; Phenotype; Protein-Serine-Threonine Kinases; Proteins; Reaction; Receptor Gene; Resolution; Site; Testing; V(D)J Recombination; ataxia telangiectasia mutated protein; base; lymphoid neoplasm; mouse model; protein function; repaired; response

DESCRIPTION (provided by applicant): Mutations in the gene encoding the ATM serine-threonine kinase cause Ataxia Telangiectasia (A-T), a disease marked by lymphopenia and an increased incidence of lymphoid tumors with translocations involving antigen receptor loci, suggesting that ATM functions during V(D)J recombination. ATM activates cell cycle checkpoints in response to DNA double strand breaks (DSBs). However, the lymphoid phenotypes of A-T are not recapitulated in mice with isolated deficiencies in checkpoint pathways. We have demonstrated that ATM functions to repair DSBs generated during V(D)J recombination, and to suppress the aberrant resolution of these DSBs as chromosomal translocations. The combined defect in checkpoint pathways and DSB repair explains some of the lymphoid phenotypes of A-T. Given all of the defects in V(D)J recombination observed in ATM-deficient lymphocytes, we have proposed that ATM functions, in part, to maintain the stability of DSB complexes after RAG-mediated DNA cleavage, which is a hypothesis that will be directly tested in Specific Aim One. Although ATM could function directly in the repair of RAG-mediated DSBs, we expect that ATM will likely phosphorylate proteins that perform this function. In this regard we show that the MRN complex (Mre11, Rad50 and Nbs1), 53BP1 and H2AX, which are all targets of ATM, function in the response to RAG-mediated DSBs. How these proteins function in the ATM-dependent pathway of RAG-DSB repair will be elucidated in Specific Aim Two. In addition, we will consider the possibility that the RAG proteins may have ATM-dependent functions in the joining step of the V(D)J recombination reaction. Importantly, we believe that these different proteins will function in an integrated manner in the ATM-dependent RAG-DSB repair pathway. Finally, we will investigate the mechanisms by which DNA DSBs generated during V(D)J recombination in ATM-deficient cells become aberrantly resolved as chromosomal translocations (Specific Aim 3). The completion of these aims will provide important new information about: 1) how RAG-mediated DSBs are repaired; 2) how ATM functions in DSB repair and in maintaining genomic stability; and 3) the mechanisms that promote the formation of chromosomal translocations.

描述（由申请方提供）：编码ATM丝氨酸-苏氨酸激酶的基因突变导致共济失调毛细血管扩张症（A-T），这是一种以淋巴细胞减少和淋巴肿瘤发生率增加为特征的疾病，伴有涉及抗原受体基因座的易位，表明ATM在V（D）J重组过程中发挥作用。ATM激活细胞周期检查点以响应DNA双链断裂（DSB）。然而，A-T的淋巴表型在检查点途径中具有孤立缺陷的小鼠中不重现。我们已经证明，ATM的功能，以修复在V（D）J重组过程中产生的DSB，并抑制这些DSB作为染色体易位的异常分辨率。检查点通路和DSB修复的组合缺陷解释了A-T的一些淋巴表型。鉴于在ATM缺陷淋巴细胞中观察到的V（D）J重组中的所有缺陷，我们提出ATM的功能部分是在RAG介导的DNA切割后维持DSB复合物的稳定性，这是一个将在Specific Aim One中直接测试的假设。虽然ATM可以直接在RAG介导的DSB修复中发挥作用，但我们预计ATM可能会磷酸化执行此功能的蛋白质。在这方面，我们表明，MRN复合物（Mre 11，Rad 50和Nbs 1），53 BP 1和H2 AX，这都是ATM的目标，在RAG介导的DSB的响应功能。这些蛋白质如何在RAG-DSB修复的ATM依赖性途径中发挥作用将在具体目标2中阐明。此外，我们将考虑RAG蛋白在V（D）J重组反应的连接步骤中可能具有ATM依赖性功能的可能性。重要的是，我们相信这些不同的蛋白质将以整合的方式在ATM依赖性RAG-DSB修复途径中发挥作用。最后，我们将研究ATM缺陷细胞中V（D）J重组过程中产生的DNA DSB异常分解为染色体易位的机制（具体目标3）。这些目标的完成将提供重要的新信息：1）RAG介导的DSB如何修复; 2）ATM如何在DSB修复和维持基因组稳定性中发挥作用; 3）促进染色体易位形成的机制。