PATHWAYS THAT PRESERVE GENOME STABILITY DURING ANTIGEN RECEPTOR GENE ASSEMBLY

抗原受体基因组装过程中保持基因组稳定性的途径

基本信息

批准号：
8649628
负责人：
Bo-Ruei Chen
金额：
$ 5.51万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-02-01 至 2017-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8649628
关键词：
Antibodies Antigen Receptors Apoptosis Ataxia-Telangiectasia-Mutated protein kinase B-Lymphocytes Binding Biological Assay Cell Cycle Arrest Cell physiology Cells Chromatin Chromatin Structure Chromosomal translocation Chromosome Deletion DNA DNA Damage DNA Double Strand Break DNA Repair DNA Repair Pathway DNA Sequence DNA Sequence Rearrangement DNA lesion DNA repair protein Double Strand Break Repair Enzymes Event Excision Exons G1 Phase G2 Phase Genome Stability Genomic Instability Genotoxic Stress Histones Human In Vitro Infection Ionizing radiation Label Laboratories Lead Lesion Lymphocyte Lymphocyte antigen Lymphoid Malignant Neoplasms Malignant lymphoid neoplasm Mediating Modification Molecular Monitor Nonhomologous DNA End Joining Oncogenic Pathway interactions Phosphorylation Process Proteins Receptor Gene Recruitment Activity Research Proposals Resolution Role Signal Transduction Single-Stranded DNA Structure T-Cell Receptor Testing Variant base chromatin immunoprecipitation endonuclease fighting histone modification homologous recombination in vitro Assay in vivo insight leukemia/lymphoma novel nuclease physical separation prevent public health relevance receptor repair enzyme repaired response sensor tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): DNA double strand breaks (DSBs) are perhaps the most harmful among all types of DNA damage because they involve physical separation of DNA molecules. If un-repaired or repaired aberrantly, DSBs can lead to loss (i.e. deletion) or abnormal rearrangement (i.e. translocation) of chromosomes, which can drive the genesis of a wide variety of cancers. DSBs can be generated by genotoxic stress, such as ionizing radiation, or as intermediates of normal cellular activities, such as the assembly of antigen receptor genes in lymphocytes that encode antibodies and T cell receptors that are key to fighting infection. During the assembly process, DNA DSBs are introduced at antigen receptor gene segments, and then repaired to generate the final DNA sequence encoding antigen receptor proteins. However, under certain circumstances, such DSBs cannot be properly repaired and eventually lead to the oncogenic deletions or translocations commonly seen in leukemias and lymphomas. Our laboratory previously identified a novel pathway that has an important role in protecting DSBs at antigen receptor genes from undergoing inappropriate processing by cellular enzymes and aberrant resolution. This pathway depends on the modification of a histone protein, H2AX, that is closely associated with cellular DNA. In response to DNA double strand breaks (DSBs), H2AX is phosphorylated by DNA damage sensor kinase ATM to form ?-H2AX that functions to recruit DNA damage response and repair proteins, and mediates additional modifications on other histone proteins. We have found that the phosphorylation of H2AX associated with broken DNA ends prevents processing of these DNA ends in ways that could lead to their aberrant repair. Here we propose to elucidate the mechanisms by which H2AX functions to prevent aberrant DSB repair. We hypothesize that ?-H2AX maintains DSB end structure through mechanisms that include modulating chromatin structure and DNA end accessibility through directing additional histone PTMs. In addition, given that ?-H2AX is shown to regulate protein association at DSBs, we predict that ?-H2AX can also impact the association of nucleases at DSB ends. To test our hypothesis, we will first reveal which histone modifications are generated in response to DSBs in a ?-H2AX-dependent manner and then determine whether ?-H2AX and ?-H2AX-dependent histone modifications modulate DNA end structures in a way that renders them less susceptible to degradation by nucleases. We will then determine whether ?-H2AX may prevent aberrant DNA end processing by limiting the association of nucleases with DSB ends. These studies will further our understanding of the genesis of chromosomal lesions that lead to lymphoid transformation and have broader implications for our understanding of the basis for genome instability in a variety of cancers.

描述（由申请人提供）：DNA 双链断裂 (DSB) 可能是所有类型的 DNA 损伤中危害最大的，因为它们涉及 DNA 分子的物理分离。如果未修复或修复异常，DSB 可能导致染色体丢失（即缺失）或异常重排（即易位），从而导致多种癌症的发生。 DSB 可以通过基因毒性应激（例如电离辐射）产生，也可以作为正常细胞活动的中间体（例如编码抗感染关键抗体和 T 细胞受体的淋巴细胞中抗原受体基因的组装）产生。在组装过程中，DNA DSB 被引入抗原受体基因片段，然后修复以生成编码抗原受体蛋白的最终 DNA 序列。然而，在某些情况下，此类 DSB 无法正确修复，最终导致白血病和淋巴瘤中常见的致癌缺失或易位。我们的实验室之前发现了一种新的途径，该途径在保护抗原受体基因上的 DSB 免遭细胞酶的不当加工和异常分辨率方面发挥着重要作用。该途径依赖于与细胞 DNA 密切相关的组蛋白 H2AX 的修饰。响应 DNA 双链断裂 (DSB)，H2AX 被 DNA 损伤传感器激酶 ATM 磷酸化，形成 ?-H2AX，其功能是招募 DNA 损伤反应和修复蛋白，并介导对其他组蛋白的额外修饰。我们发现，与断裂 DNA 末端相关的 H2AX 磷酸化可阻止这些 DNA 末端的加工，从而导致异常修复。在这里，我们建议阐明 H2AX 防止异常 DSB 修复的机制。我们假设 ?-H2AX 通过指导额外的组蛋白 PTM 来调节染色质结构和 DNA 末端可及性等机制来维持 DSB 末端结构。此外，鉴于 ?-H2AX 显示可调节 DSB 处的蛋白质关联，我们预测 ?-H2AX 也可以影响 DSB 末端核酸酶的关联。为了检验我们的假设，我们将首先揭示哪些组蛋白修饰是以 ?-H2AX 依赖性方式响应 DSB 生成的，然后确定 ?-H2AX 和 ?-H2AX 依赖性组蛋白修饰是否以某种方式调节 DNA 末端结构，从而使得它们不易被核酸酶降解。然后我们将确定 ?-H2AX 是否可以通过限制核酸酶与 DSB 末端的关联来防止异常 DNA 末端加工。这些研究将进一步加深我们对导致淋巴转化的染色体病变起源的理解，并对我们理解各种癌症中基因组不稳定性的基础产生更广泛的影响。