Nuclear Receptors in B Cell Tolerance and Humoral Immune Responses

B 细胞耐受和体液免疫反应中的核受体

基本信息

批准号：
10192648
负责人：
JULIE ZIKHERMAN
金额：
$ 40.38万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-06-15 至 2025-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10192648
关键词：
Acute Address Affinity Agonist Alleles Antibody Response Antigens Architecture Autoantibodies Autoimmune Autoimmune Diseases Autoimmunity B cell differentiation B cell repertoire B-Cell Activation B-Lymphocytes Bacterial Artificial Chromosomes Base Sequence Binding Biology Cells Chronic Clone Cells Coupled DNA Binding Domain Data Defect Development Disease Enzyme-Linked Immunosorbent Assay Exhibits Family Family member Feedback Gene Expression Genes Genetic Transcription Goals Grant Immune Immune response Immunity Knowledge Ligands Lupus Lymphocyte Masks Mediating Modeling Molecular Multiple Sclerosis Mus NR4A2 gene Nuclear Hormone Receptors Nuclear Receptors Orphan Peripheral Play Process Radiation Chimera Reporter Reporting Role Signal Transduction Stains Structure Structure of germinal center of lymph node T-Lymphocyte Testing Therapeutic Vaccination Vaccines c-myc Genes expectation gene repression genetic approach genome-wide member novel novel therapeutics preservation programs recruit response single-cell RNA sequencing small molecule transcription factor unpublished works

项目摘要

Project Summary/Abstract This proposal's long-term goal is to take advantage of the biology of the Nr4a family of orphan nuclear hormone receptors to selectively manipulate antigen-specific B cell responses. If successful, this could transform our approach to vaccination and treatment of immune-mediated diseases. Nr4a family members (Nur77, Nurr1, and Nor1) are encoded by three genes (Nr4a1-3, respectively) that are rapidly induced by antigen (Ag) stimulation in lymphocytes. Although they are thought to function as ligand- independent, constitutively active transcription factors, small molecule agonist and antagonist ligands have been developed, rendering them druggable. We have shown that a fluorescent reporter of Nr4a1 expression (Nur77- eGFP BAC Tg) scales with the intensity of Ag stimulation, and also correlates with self-reactivity in naturally occurring B cells in healthy mice and in three different BCR Tg models. We have recently shown that Nur77 curbs the survival and expansion of B cells in response to chronic and acute Ag stimulation, imposing a novel layer of B cell tolerance. Importantly, the Nr4a family harbor considerable structural homology in their DNA- binding domain and, as a result, exhibit profound functional redundancy in T cells, where they also play an important regulatory role. Such redundancy is likely highly relevant to their function in B cells (which predominantly express Nr4a1 and Nr4a3) yet has never been experimentally addressed. This represents a major gap in our knowledge that limits full therapeutic exploitation of these factors. Here we report that newly generated mice with B cell-specific deletion of Nr4a1 and Nr4a3 show a major break in B cell tolerance, including the development of spontaneous germinal centers and autoantibodies. These defects correlate with profound super-induction of novel target genes in response to Ag stimulation – including several genes required for recruitment of T cell help – that is largely masked when even one functional Nr4a allele remains. We therefore hypothesize that the Nr4a family mediates negative feedback downstream of Ag stimulation via transcriptional repression of key target genes. We propose that this serves two functions: (a) to restrain self-reactive clones that receive signal 1 (antigen) in the absence of signal 2 (co-stimulation), and (b) restrain immunodominant clones from monopolizing normal humoral immune responses, in order to preserve clonal diversity. In this grant, we propose: (1) To define the role of the Nr4a family in regulating central and peripheral B cell tolerance, and identify transcriptional mechanisms that mediate these functions in BCR Tg and naturally occurring self-reactive B cells. (2) To define the role of the Nr4a family in regulating B cell inter-clonal competition and clonal diversity during the primary T-dependent humoral immune response and its contribution to limiting immunodominance. (3) To define the role of the newly identified Nr4a target gene Batf in mediating these processes.

项目概要/摘要该提案的长期目标是利用孤儿核激素 Nr4a 家族的生物学特性受体选择性操纵抗原特异性 B 细胞反应如果成功，这可能会改变我们的研究。免疫介导疾病的疫苗接种和治疗方法。 Nr4a 家族成员（Nur77、Nurr1 和 Nor1）由三个基因（分别为 Nr4a1-3）编码，这三个基因分别是淋巴细胞中的抗原（Ag）刺激可快速诱导，尽管它们被认为具有配体功能。独立的、组成型活性转录因子、小分子激动剂和拮抗剂配体已被我们已经证明了 Nr4a1 表达的荧光报告基因（Nur77-）。 eGFP BAC Tg) 与 Ag 刺激的强度成比例，并且还与自然状态下的自身反应性相关我们最近证明，Nur77 存在于健康小鼠和三种不同的 BCR Tg 模型中。抑制 B 细胞响应慢性和急性 Ag 刺激的存活和扩增，从而产生一种新的重要的是，Nr4a 家族在其 DNA 中具有相当大的结构同源性。结合域，因此在 T 细胞中表现出深刻的功能冗余，它们也在 T 细胞中发挥着重要作用这种冗余可能与它们在 B 细胞中的功能高度相关。主要表达 Nr4a1 和 Nr4a3），但从未通过实验得到解决。我们知识上的一个重大差距限制了这些因素的充分治疗利用。在这里，我们报告了新产生的 B 细胞特异性删除 Nr4a1 和 Nr4a3 的小鼠显示出重大突破 B 细胞耐受性，包括自发生发中心和自身抗体的发育。缺陷与新靶基因响应 Ag 刺激的深度超诱导相关，包括招募 T 细胞所需的几个基因有助于——即使只有一个有功能的 Nr4a 也很大程度上掩盖了这一点因此，我们发现 Nr4a 家族介导 Ag 下游的负反馈。我们认为这有两个功能：（a）在没有信号 2（共刺激）的情况下抑制接收信号 1（抗原）的自身反应克隆，以及 (b) 抑制免疫显性克隆垄断正常的体液免疫反应，以保护在这项资助中，我们建议： (1) 明确Nr4a家族在调节中枢和外周B细胞耐受中的作用，并鉴定 BCR Tg 和自然发生的自身反应性 B 细胞中介导这些功能的转录机制。 (2)明确Nr4a家族在调节B细胞克隆间竞争和克隆多样性过程中的作用主要 T 依赖性体液免疫反应及其对限制免疫优势的贡献。 (3) 明确新鉴定的Nr4a靶基因Batf在介导这些过程中的作用。