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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要生发中心 (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。我们之前证明GC B细胞可以细分为三个在功能、空间、转录和表观遗传上不同的亚群。因此，我们问这些独特的表观遗传状态对于 GC B 细胞功能和分化是否重要。我们实验室还先前描述了表观遗传阅读器 BRWD1 如何调节表观遗传状态和增强子 B 细胞淋巴细胞生成过程中从大前 B 细胞向小前 B 细胞转变期间的可及性。因为 BRWD1 在 GC B 细胞中高表达，我们假设 BRWD1 调节 GC B 细胞中的染色质可及性 GC B 细胞对于外周 B 细胞分化很重要。为了研究这一点，我们生成了 Brwd1floxed 小鼠删除不同 B 细胞群中的 Brwd1。首先，滤泡 B 细胞中 Brwd1 的缺失抑制了 GC 反应显微镜下观察到的 GC B 细胞较少，GC 较小。二、GC B细胞中Brwd1的缺失促进 GC B 细胞增殖并阻止 Brwd1-/- GC B 细胞分化为记忆 B 细胞，而无需破坏 GC 架构。此外，Brwd1 的缺失导致表观遗传崩溃，从而导致差异 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 BRWD1 调节增强子和转录因子结合基序的染色质可及性的模型方式对于外周 B 细胞的细胞命运决定至关重要。为了测试这个模型，首先我们将进一步研究如何 BRWD1 对于 B 细胞功能和分化很重要。在滤泡 B 细胞中，我们将表征是否 BRWD1 对于 GC B 细胞的初始分化或早期扩增和增殖是必需的（目的 1）。在GC B细胞中，我们将研究BRWD1对于体细胞超突变和亲和力成熟是否重要（目标 2A）。此外，我们将确定 BRWD1 是否是前记忆 B 细胞发育所必需的或记忆 B 细胞亚群（目标 2B）。最后，我们将描述 BRWD1 如何建立表观遗传状态 GC B 细胞亚群之间的差异（目标 3）。我们将描述 BRWD1 如何在不同位点结合以及如何结合招募 BRWD1 的组蛋白标记在 GC 区域之间发生变化。我们将识别活跃的和压抑的增强子与染色质可及性数据一起研究 BRWD1 如何协调增强子的变化 GC B 细胞亚群之间的可及性。完成该拟议项目将有助于深入了解体液免疫反应、自身免疫和淋巴瘤发展的核心基本机制 GC 内。