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.

项目摘要 精确控制淋巴细胞的发育以实现克隆扩张和表达多样的表达 免疫球蛋白受体曲目，通过由DNA双链断裂（DSB）进行 抹布内切酶。这两个二分法但相互依存的过程是通过 各种细胞信号的合作，以防止DSB的细胞进入细胞周期 异常修复为易位。在早期B细胞发育期间，PRE-B细胞受体（前BCR）通过 激活SYK激酶，辅助B细胞的增殖性膨胀和组装 免疫球蛋白受体基因。需要BCR的负调节以确保细胞周期停滞和 限制在免疫球蛋白受体基因组装过程中产生的DNA断裂数量。确实，没有反对 BCR前信号传导，特别是增加SYK活性，可驱动增殖和白血病转化。 但是，抑制SYK和前BCR信号传导的机制尚不清楚，并且在 我们对B细胞成熟的理解。我们已经确定了一个由信号激活的新型细胞类型特定程序 从抑制SYK并抑制前BCR信号传导的RAG DSB中。该DNA损伤的缺陷 - 介导的反馈电路导致启动前B细胞白血病。令人惊讶的是，这个信号网络不是 由所有DNA损伤触发，但特定于免疫球蛋白受体基因期间产生的抹布DSB 集会。我们的目标是确定RAG DSB的信号如何与发展程序集成 协调B细胞成熟并防止白血病转化。我们建议抹布DSB 抑制SYK以强制执行细胞周期停滞，从而防止DNA断裂重新输入细胞的B细胞 循环。该DNA损伤介导的检查点程序将允许迭代尝试成熟 抗原受体可促进B细胞分化，同时预防白血病开始。此外，我们建议 这些DNA损伤信号通过与抹布内切酶的不同域激活，与之相互作用 DSB位置的蛋白质调节信号通路。 B细胞中的这种抹布特异性机制可区分 在正常和错误的DSB之间激活适当的细胞反应。利用创新的实验 可以在B细胞开发程序的背景下询问DSB信号的方法 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介导的rag介导的机制与非碎片介导的DNA损伤。这些研究的完成 将描绘出对早期B细胞中增殖信号至关重要的途径，建立限制的信号 白血病生成并定义了抹布内切核酸酶在调节DNA损伤反应中的新功能。