RAG-mediated DNA Damage Responses in Immune Development and Function

RAG 介导的免疫发育和功能中的 DNA 损伤反应

• 批准号: 10566822
• 负责人: Jeffrey J Bednarski
• 金额: $ 51.48万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-19 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10566822
• 关键词: Antigen Receptors; Automobile Driving; B Cell Proliferation; B cell differentiation; B-Cell Acute Lymphoblastic Leukemia; B-Cell Development; B-Cell Leukemia; B-Lymphocytes; Binding; Cell Cycle; Cell Cycle Arrest; Cell Maturation; Cells; Clonal Expansion; Complex; Critical Pathways; DNA; DNA Damage; DNA Double Strand Break; DNA Integration; Development; Ensure; Family; Feedback; G1 Arrest; Gene Expression; Generations; Genes; Genetic Recombination; Genetic Transcription; Goals; Immune; Immunity; Immunoglobulin Light Chain Genes; Lead; Light-Chain Immunoglobulins; Lymphocyte; Malignant Neoplasms; Mediating; Modeling; Mus; N-terminal; Pathway interactions; Phosphotransferases; Process; Property; Proteins; Receptor Gene; Regulation; Reporter; Repression; Repressor Proteins; SYK gene; Signal Pathway; Signal Transduction; Site; System; TP53 gene; Testing; Transcription Coactivator; Transcription Repressor; Tumor Suppressor Proteins; Work; cell assembly; cell type; cellular engineering; endonuclease; immunoglobulin receptor; innovation; insight; leukemia; leukemic transformation; leukemogenesis; novel; novel strategies; novel therapeutics; pre-B cell receptor; prevent; programs; protein complex; receptor; recruit; repaired; response; transcription factor

PROJECT SUMMARY Lymphocyte development is precisely controlled to enable clonal expansion and expression of a diverse immunoglobulin receptor repertoire, which proceeds through DNA double-stranded breaks (DSBs) generated by the RAG endonuclease. These two dichotomous, but interdependent processes, are managed through the cooperation of diverse cellular signals to prevent cells with DSBs from entering cell cycle where they could be aberrantly repaired as translocations. During early B cell development, the pre-B cell receptor (pre-BCR), through activation of the SYK kinase, coordinates both the proliferative expansion of pre-B cells and the assembly of immunoglobulin receptor genes. Negative regulation of the pre-BCR is required to ensure cell cycle arrest and limit the number of DNA breaks generated during immunoglobulin receptor gene assembly. Indeed, unopposed pre-BCR signaling, particularly increased SYK activity, drives proliferation and leukemic transformation. However, the mechanisms that repress SYK and pre-BCR signaling are not known and remain a critical gap in our understanding of B cell maturation. We have identified a novel cell-type specific program activated by signals from RAG DSBs that suppresses SYK and inhibits pre-BCR signaling. Deficiencies in this DNA damage- mediated feedback circuit result in initiation of pre-B cell leukemia. Surprisingly, this signaling network is not triggered by all DNA injury but, rather, is specific to RAG DSBs generated during immunoglobulin receptor gene assembly. Our goal is to determine how signals from RAG DSBs integrate with developmental programs to coordinate B cell maturation and prevent leukemic transformation. We propose that RAG DSBs suppress SYK to enforce cell cycle arrest and, thereby prevent B cells with DNA breaks from re-entering cell cycle. This DNA damage-mediated checkpoint program would permit iterative attempts at generation of a mature antigen receptor to promote B cell differentiation while preventing leukemic initiation. Further, we propose that these DNA damage signals are activated through distinct domains of the RAG endonuclease that interact with proteins at sites of DSBs to modulate signaling pathways. This RAG-specific mechanism in B cells discriminates between normal and errant DSBs to activate appropriate cellular responses. Utilizing an innovative experimental approach that allows interrogation of DSB signals within the context of B cell developmental programs, our proposed studies will define how RAG DSB signals maintain pre-B cell checkpoint and will resolve the mechanisms that distinguish RAG-mediated from non-RAG-mediated DNA damage. Completion of these studies will delineate pathways critical for dampening proliferative signals in early B cells, establish signals that restrict leukemogenesis, and define novel functions of the RAG endonuclease in regulating DNA damage responses.

项目概要 精确控制淋巴细胞的发育，以实现多种细胞的克隆扩增和表达 免疫球蛋白受体库，通过 DNA 双链断裂 (DSB) 产生 RAG核酸内切酶。这两个二分但相互依赖的过程通过 不同细胞信号的合作，以防止带有 DSB 的细胞进入它们可能进入的细胞周期 作为易位被异常修复。在早期 B 细胞发育过程中，前 B 细胞受体 (pre-BCR) 通过 SYK 激酶的激活，协调前 B 细胞的增殖扩张和 免疫球蛋白受体基因。需要对前 BCR 进行负调节以确保细胞周期停滞和 限制免疫球蛋白受体基因组装过程中产生的 DNA 断裂数量。确实，无人反对 BCR 前信号传导，特别是 SYK 活性的增加，可促进增殖和白血病转化。 然而，抑制 SYK 和前 BCR 信号传导的机制尚不清楚，并且仍然是一个关键的空白。 我们对 B 细胞成熟的理解。我们发现了一种由信号激活的新型细胞类型特异性程序 来自 RAG DSB，可抑制 SYK 并抑制前 BCR 信号传导。这种DNA损伤的缺陷- 介导的反馈回路导致前B细胞白血病的发生。令人惊讶的是，这个信号网络并不是 由所有 DNA 损伤触发，但特定于免疫球蛋白受体基因过程中产生的 RAG DSB 集会。我们的目标是确定来自 RAG DSB 的信号如何与发育程序整合 协调 B 细胞成熟并防止白血病转化。我们建议 RAG DSB 抑制 SYK 以强制细胞周期停滞，从而防止 DNA 断裂的 B 细胞重新进入细胞 循环。这种 DNA 损伤介导的检查点程序将允许迭代尝试生成成熟的 抗原受体促进 B 细胞分化，同时防止白血病发生。此外，我们建议 这些 DNA 损伤信号通过 RAG 核酸内切酶的不同结构域被激活，这些结构域与 DSB 位点上的蛋白质可调节信号通路。 B 细胞中的这种 RAG 特异性机制可区分 正常和错误 DSB 之间的差异，以激活适当的细胞反应。利用创新的实验 允许在 B 细胞发育程序的背景下询问 DSB 信号的方法，我们的 拟议的研究将定义 RAG DSB 信号如何维持前 B 细胞检查点，并将解决 区分 RAG 介导和非 RAG 介导的 DNA 损伤的机制。完成这些研究 将描绘出抑制早期 B 细胞增殖信号的关键途径，建立限制信号 白血病发生，并定义 RAG 核酸内切酶在调节 DNA 损伤反应中的新功能。