The role of BRWD1 to establish epigenetic states for germinal center initiation, maintenance, and exit

BRWD1 在建立生发中心启动、维持和退出的表观遗传状态中的作用

• 批准号: 10599635
• 负责人: Nathaniel Edwin Wright
• 金额: $ 5.27万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10599635
• 关键词: Affinity; Antibody Affinity; Antigens; Architecture; Autoimmunity; B cell differentiation; B-Lymphocyte Subsets; B-Lymphocytes; Binding; Binding Sites; Bioinformatics; Cell Differentiation process; Cell Fate Control; Cell Proliferation; Cell physiology; Cells; Chromatin; Darkness; Data; Development; Enhancers; Epigenetic Process; Follicular Dendritic Cells; Genetic Transcription; Helper-Inducer T-Lymphocyte; Histones; Humoral Immunities; Immune response; Immunization; Immunoglobulin Somatic Hypermutation; Immunologic Memory; Infection; Knock-out; Light; Lymphoma; Lymphopoiesis; Maintenance; Malignant - descriptor; Manuscripts; Mature B-Lymphocyte; Measures; Memory; Memory B-Lymphocyte; Microscopy; Modeling; Mus; Peripheral; Plasma Cells; Population; Process; Proliferating; Publishing; Reaction; Reader; Regulation; Repression; Research; Role; Site; Structure of germinal center of lymph node; T-Lymphocyte; Testing; Tingible Body Macrophage; Transcriptional Regulation; Work; antigen binding; autoreactive B cell; experimental study; insight; prevent; programs; recruit; response; timeline; transcription factor

PROJECT SUMMARY Germinal centers (GCs) drive adaptive humoral immunity by selecting for B cells with high affinity antibodies and producing memory B cells and plasma cells. We previously demonstrated that GC B cells can be subdivided into three subpopulations that are functionally, spatially, transcriptionally, and epigenetically distinct. Thus, we asked whether these unique epigenetic states are important for GC B cell function and differentiation. Our lab has also previously characterized how the epigenetic reader BRWD1 regulates epigenetic states and enhancer accessibility during the transition from large pre-B cells to small pre-B cells during B cell lymphopoiesis. Because BRWD1 is highly expressed in GC B cells, we hypothesized that BRWD1 regulates chromatin accessibility in GC B cells and is important for peripheral B cell differentiation. To study this, we generated Brwd1floxed mice to delete Brwd1 in different B cell populations. First, deletion of Brwd1 in follicular B cells inhibited GC responses with fewer GC B cells and smaller GCs observed by microscopy. Second, deletion of Brwd1 in GC B cells promoted proliferation of GC B cells and blocked differentiation of Brwd1-/- GC B cells into memory B cells without disrupting GC architecture. Furthermore, loss of Brwd1 caused an epigenetic collapse whereby differential chromatin accessibility between GC B cell subpopulations was lost. From this preliminary data, we propose a model where BRWD1 regulates chromatin accessibility at enhancers and transcription factor binding motifs in a manner critical for the cell fate decisions of peripheral B cells. To test this model, first we will further study how BRWD1 is important for B cell function and differentiation. In follicular B cells, we will characterize whether BRWD1 is necessary for either the initial differentiation or early expansion and proliferation of GC B cells (Aim 1). In GC B cells, we will study whether BRWD1 is important for somatic hypermutation and affinity maturation (Aim 2A). Furthermore, we will determine whether BRWD1 is necessary for development of pre-memory B cells or memory B cell subsets (Aim 2B). Finally, we will characterize how BRWD1 establishes epigenetic states between GC B cell subpopulations (Aim 3). We will characterize how BRWD1 binds at different sites and how the histone marks that recruit BRWD1 change between GC zones. We will identify active and repressed enhancers alongside our chromatin accessibility data to study how BRWD1 coordinates changes in enhancer accessibility between GC B cell subpopulations. Completion of this proposed project will provide insight into fundamental mechanisms central to the humoral immune response, autoimmunity, and lymphoma development within the GC.

项目摘要 老年中心（GC）通过选择具有高亲和力抗体的B细胞来驱动适应性体液免疫， 产生记忆B细胞和浆细胞。我们以前证明GC B细胞可以细分为 三个亚群在功能、空间、转录和表观遗传上不同。因此，我们要求 这些独特的表观遗传状态对GC B细胞功能和分化是否重要。我们的实验室还 先前表征了表观遗传阅读器BRWD 1如何调节表观遗传状态和增强子 在B细胞淋巴细胞生成过程中从大的前B细胞向小的前B细胞转变期间的可接近性。因为 BRWD 1在GC B细胞中高度表达，我们假设BRWD 1调节GC细胞中的染色质可及性。 GC B细胞，并且对于外周B细胞分化是重要的。为了研究这一点，我们产生了Brwd 1floxed小鼠， 在不同的B细胞群体中缺失Brwd 1。首先，滤泡B细胞中Brwd 1的缺失抑制了GC反应 显微镜下观察到GC B细胞较少，GC较小。第二，GC B细胞中Brwd 1的缺失 促进GC B细胞的增殖并阻断Brwd 1-/- GC B细胞向记忆B细胞的分化， 破坏GC架构。此外，Brwd 1的缺失导致了表观遗传崩溃， GC B细胞亚群之间的染色质可及性丧失。根据这些初步数据，我们提出了一个 BRWD 1调节增强子和转录因子结合基序处染色质可及性的模型， 决定外周B细胞命运的关键方式。为了检验这个模型，首先我们将进一步研究如何 BRWD 1对B细胞功能和分化是重要的。在滤泡B细胞中，我们将描述 BRWD 1对GC B细胞的初始分化或早期扩增和增殖是必需的（Aim 1）。在GC B细胞中，我们将研究BRWD 1是否对体细胞超突变和亲和力成熟很重要 (Aim 2A）。此外，我们将确定BRWD 1是否是前记忆B细胞发育所必需的 或记忆B细胞亚群（Aim 2B）。最后，我们将描述BRWD 1如何建立表观遗传状态 GC B细胞亚群之间（目的3）。我们将描述BRWD 1如何在不同的位点结合，以及如何在不同的位点结合。 招募BRWD 1的组蛋白标志物在GC区之间发生变化。我们将区分活跃和压抑 增强子与我们的染色质可及性数据一起研究BRWD 1如何协调增强子的变化， GC B细胞亚群之间的可接近性。该项目的完成将使我们深入了解 体液免疫反应、自身免疫和淋巴瘤发展的基本机制 在GC中。