Somatic hypermutation and rescue from self-reactivity in Pre-B lymphocytes

Pre-B 淋巴细胞的体细胞超突变和自身反应的拯救

• 批准号: 10153689
• 负责人: JOSHY JACOB
• 金额: $ 21.17万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10153689
• 关键词: Adoptive Transfer; Affinity; Antigens; Autoantigens; Autoimmunity; B cell repertoire; B-Cell Activation; B-Cell Antigen Receptor; B-Cell Development; B-Lymphocyte Subsets; B-Lymphocytes; Back; Bone Marrow; CD19 gene; Cell surface; Cells; Clonal Anergy; Clonal Deletion; Clonality; Clone Cells; Collaborations; Data; Dose; Enterobacteria phage P1 Cre recombinase; Exhibits; Frequencies; Generations; Genes; Humoral Immunities; IL2RA gene; IgE; Immature Bone; Immune response; Immune system; Immunity; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin Genes; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; J segment gene; Lead; Light; Link; Mature B-Lymphocyte; Mediating; Memory; Mus; Mutate; Mutation; PTPRC gene; Plasmids; Play; Point Mutation; Positioning Attribute; Pre-B Lymphocyte; Process; Property; Proteins; Reporter; Role; Somatic Mutation; Specificity; Structure; Structure of germinal center of lymph node; Testing; Time; Transgenic Mice; V(D)J Recombination; Work; activation-induced cytidine deaminase; autoreactivity; base; influenzavirus; mutant; promoter; receptor; recombinase; screening; surrogate light chain

PROJECT SUMMARY The generation of B cell receptor diversity is mediated by RAG recombinases, and it occurs during B cell development in the bone marrow. This is brought about by stochastic rearrangement of V(D)J gene segments to assemble the B cell receptor. These stochastic rearrangements also lead to the development of B cells that recognize self-antigens. These self-reactive B cell clones are dealt with by either clonal deletion, clonal anergy or RAG recombinase-mediated rescue of self-reactive clones by V gene segment replacement. In this proposal, we present an additional mechanism by which autoreactive pre-B cells are rescued from self-reactivity. We propose that Activation-induced Cytidine Deaminase (AID) plays a role in rescuing self-reactive pre-B cells. AID induces two significant genetic alterations in antigen-activated mature B cells; somatic hypermutation and class switch recombination. The former generates high-affinity B cell mutants that are enticed to enter the memory pool, and the latter facilitates Ig isotype switching from IgM to IgG, IgA or IgE. Interestingly, it has been known for over two decades that a small fraction of immature, bone marrow pre-B cells undergo class switching. This is perplexing because it occurs even in pre-B cells which have only rearranged their Ig heavy chain and are yet to rearrange their light chains. We, based on very preliminary data may have an answer to this puzzle. Our central hypothesis is that immature, self-reactive pre-B cells turn on AID and undergo somatic mutation in order to alter their specificity from self- to non-self-reactivity. The class switching that occurs in these bone marrow pre-B cells is a collateral consequence of AID expression. We will test our central hypothesis in two aims. The proposed work is significant because, upon completion, we will have established a new paradigm to explain the rescue of pre-B cells from self-reactivity. We are well- positioned to carry out the proposed studies as our team with the addition of collaborator Dr. Ignacio Sanz, one of the world’s premier experts on autoimmunity, has the requisite collective expertise to complete the proposed studies successfully.

项目总结 B细胞受体多样性的产生是由RAG重组酶介导的，它发生在 B细胞在骨髓中的发育。这是由随机重排 V(D)J基因片段组装B细胞受体。这些随机的重排也 导致识别自身抗原的B细胞的发展。这些自我反应的B细胞克隆 通过克隆性缺失、克隆性无能或RAG重组酶介导的拯救 通过V基因片段替换进行自我反应克隆。在这份提案中，我们提出了一个额外的 自身反应性前B细胞从自身反应性中解救出来的机制。我们建议 激活诱导型胞苷脱氨酶(AID)在抢救自身反应性Pre-B细胞中起重要作用。 AID在抗原激活的成熟B细胞中诱导两个显著的遗传变化；体细胞 超突变和类交换重组。前者产生高亲和力的B细胞突变体 它们被引诱进入内存池，而后者促进了从Ig同型向Ig的转换 对免疫球蛋白、免疫球蛋白A或免疫球蛋白E。 有趣的是，二十多年来，人们已经知道一小部分未成熟的骨骼 骨髓前B细胞经历分类转换。这是令人费解的，因为它甚至出现在前B 只重新排列免疫球蛋白重链而尚未重新排列轻链的细胞。 我们，基于非常初步的数据，可能会有这个谜题的答案。我们的中心假设 是未成熟的、自我反应的前B细胞启动艾滋病并经历体细胞突变以 将他们的专一性从自我反应性改变为非自我反应性。在这些骨骼中发生的类转换 骨髓前B细胞是AID表达的副产物。我们将测试我们的中央 假设有两个目的。拟议的工作意义重大，因为完成后，我们将拥有 建立了一个新的范式来解释前B细胞从自我反应性中解救出来的原因。我们很好- 作为我们的团队，在增加合作者Dr。 伊格纳西奥·桑兹，世界上首屈一指的自身免疫专家之一，拥有必要的集体 成功完成拟议研究的专业知识。