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: 10707193
• 负责人: Jeffrey J Bednarski
• 金额: $ 50.89万
• 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/10707193
• 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; Proliferating; Property; Proteins; Rag1 Mouse; Receptor Gene; Receptor Signaling; Regulation; Reporter; Repression; Repressor Proteins; SYK gene; Signal Pathway; Signal Transduction; Site; System; TP53 gene; Testing; Transcription Coactivator; Transcription Repressor; Tumor Suppressor Proteins; Visualization; Work; 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; recruit; repaired; response; segregation; 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.

项目总结 淋巴细胞的发育受到精确控制，以使克隆扩增和表达不同的 免疫球蛋白受体谱系，通过DNA双链断裂(DSB)进行的 碎屑核酸内切酶。这两个二分但相互依赖的进程通过 不同细胞信号的协同作用，防止双链断裂的细胞进入细胞周期 以移位的形式被异常修复。在B细胞发育的早期，前B细胞受体(Pre-BCR)，通过 SYK激酶的激活，协调前B细胞的增殖扩张和组装 免疫球蛋白受体基因。需要负调控Pre-BCR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。事实上，没有人反对 BCR前信号，尤其是SYK活性增强，驱动细胞增殖和白血病转化。 然而，抑制SYK和Pre-BCR信号的机制尚不清楚，并且仍然是 我们对B细胞成熟的理解。我们已经确定了一种由信号激活的新的细胞类型特异性程序 来自抑制SYK和抑制Pre-BCR信号的RAG DSB。这种DNA损伤的缺陷- 介导的反馈回路导致前B细胞白血病的启动。令人惊讶的是，这个信令网络并不 由所有DNA损伤触发，而不是针对免疫球蛋白受体基因产生的RAG DSB 集合。我们的目标是确定来自RAG DSB的信号如何与发育计划相结合 协调B细胞成熟，防止白血病转化。我们建议将碎布DSB 抑制SYK，使细胞周期停止，从而阻止DNA断裂的B细胞重新进入细胞 周而复始。这种DNA损伤介导的检查点计划将允许在成熟的 促进B细胞分化的抗原受体，同时防止白血病的发生。此外，我们建议 这些DNA损伤信号是通过RAG内切酶的不同结构域激活的，这些结构域与 DSB位点上的蛋白质来调节信号通路。B细胞中这种RAG特异的机制可以区分 在正常和错误的DSB之间，以激活适当的细胞反应。利用创新的实验 允许在B细胞发育计划的背景下询问DSB信号的方法，我们的 拟议的研究将定义RAG DSB信号如何维护前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 白血病的发生，并定义了RAG内切酶在调节DNA损伤反应中的新功能。