Functions and mechanisms of transcriptional coactivator OCA-B in B cell development and lymphomagenesis

转录共激活因子 OCA-B 在 B 细胞发育和淋巴瘤发生中的功能和机制

基本信息

批准号：
10528447
负责人：
SOHAIL MALIK
金额：
$ 73.75万
依托单位：
ROCKEFELLER UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-12-12 至 2024-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10528447
关键词：
Adaptive Immune System Address Affinity Anatomy Antibodies Antigens Autoimmune Diseases Autoimmunity B cell differentiation B-Cell Development B-Cell Lymphomas B-Lymphocytes BCL6 gene Binding Biochemical Bioinformatics Biological Assay Burkitt Lymphoma C-terminal Cell Culture System Cell Line Cell Maturation Cell Proliferation Cells Chromatin Clonal Expansion Complex DNA Data Defect Dependence Development Disease Distal Drug Targeting Enhancers Epigenetic Process Gene Activation Genes Genetic Genetic Transcription Genomic approach Genomics Goals Health Hematopoietic stem cells Human Immune Immune response Immune system Immunoglobulin Genes Immunoglobulin Somatic Hypermutation Immunoglobulin-Secreting Cells Immunologic Stimulation Immunotherapy Impairment In Vitro Knockout Mice Locus Control Region Lymphoid Lymphoma Lymphoma cell Lymphomagenesis Malignant Neoplasms Mediating Mediator Memory B-Lymphocyte Microanatomy Molecular Mechanisms of Action Mutation Oncogenic Pathway interactions Physical condensation Play Process Proteomics Recombinants Recurrence Reporter Reporting Response Elements Role Series Signal Pathway Site Specific qualifier value Structure of germinal center of lymph node System Time Transcription Coactivator Transcriptional Regulation candidate identification cell growth cofactor genetic approach imaging approach in vivo insight large cell Diffuse non-Hodgkin&apos s lymphoma mouse model neoplastic cell novel therapeutic intervention programs promoter reconstitution recruit response secondary lymphoid organ transcription factor

项目摘要

PROJECT SUMMARY A functional immune system is central to human health and, at the same time, alterations of normal lymphoid developmental programs can lead to immune deficiencies, autoimmune diseases and a variety of lymphomas. Germinal centers (GCs) are microanatomical structures formed in secondary lymphoid organs during antigen- stimulated immune responses. GCs are the sites of B cell maturation through clonal expansion, somatic hypermutation, and affinity-mediated selection -- and therefore play a critical role in differentiation of antibody secreting cells and memory B cells. OCA-B is a unique transcriptional coactivator that is highly expressed in GC B cells and GC-derived lymphomas such as diffuse large B cell lymphoma and Burkitt’s lymphoma. In vivo studies have demonstrated that OCA-B is essential for both antigen-dependent B cell differentiation (including GC formation) and normal expression of secondary immunoglobulin genes. However, little is known about the exact role of OCA-B in normal GC formation and GC-derived lymphoma progression. In addition, the mechanism by which OCA-B regulates its target genes is also unclear. In addressing these issues, our preliminary studies have demonstrated (i) a functional occupancy of OCA-B on distal enhancers, in particular the large locus control region (LCR) of the BCL6 gene that encodes a master regulator of GC formation; (ii) direct interactions of OCA- B with the MED1 subunit of the Mediator coactivator complex and with a GC-specific transcription factor (MEF2B) important for BCL6 expression and (iii) a B cell-intrinsic Oca-B dependency for GC B cell differentiation in vivo. Based on our previous OCA-B studies and recent preliminary data, we hypothesize that a predominant role of OCA-B in GC formation involves activation of BCL6 through its distal enhancer region by recruiting and concentrating transcription factors and cofactors, including chromatin/epigenetic factors, that facilitate enhancer- promoter interactions. We also hypothesis that OCA-B plays a critical role in GC-derived lymphomagenesis. To address these issues, we will investigate (i) the function and mechanism of action of OCA-B, through interactions with MED1/Mediator and MEF2B, on the BCL6 LCR/super-enhancer in both ex vivo GC B and lymphoma cells, (ii) the mechanism of action of OCA-B-dependent transcriptional coactivation through rigorous biochemical in vitro transcription assays; (iii) the mechanism of action of OCA-B in GC B cell differentiation in vivo, including identification of key target genes and regulatory networks; (iv) the role of OCA-B in B cell lymphoma progression in vivo. We will use complementary biochemical, genomic, bioinformatic, genetic, gene-editing, cell-based and in vivo (mouse model) approaches. Completion of these aims will advance our understanding of the molecular mechanism of action of OCA-B in GC-specific transcriptional regulation, GC B cell differentiation, and GC- derived B cell lymphomagenesis. Notably, it also will provide clues to new therapeutic strategies for treating B cell lymphomas.

项目概要功能性免疫系统对于人类健康至关重要，同时也影响正常淋巴系统的改变发育计划可能导致免疫缺陷、自身免疫性疾病和各种淋巴瘤。生发中心（GC）是在抗原-免疫过程中在次级淋巴器官中形成的显微解剖结构。 GC 是 B 细胞通过克隆扩增、体细胞成熟的场所。超突变和亲和力介导的选择——因此在抗体的分化中发挥着关键作用 OCA-B 是一种独特的转录共激活因子，在 GC 中高度表达。 B 细胞和 GC 衍生的淋巴瘤，例如弥漫性大 B 细胞淋巴瘤和伯基特淋巴瘤体内。研究表明 OCA-B 对于抗原依赖性 B 细胞分化（包括 GC 形成）和次级免疫球蛋白基因的正常表达然而，人们对此知之甚少。 OCA-B 在正常 GC 形成和 GC 衍生淋巴瘤进展中的确切作用。 OCA-B通过何种方式调节其靶基因也不清楚。在解决这些问题时，我们的初步研究还不清楚。已经证明 (i) OCA-B 对远端增强子的功能占据，特别是大基因座控制 BCL6 基因的区域 (LCR) 编码 GC 形成的主调节因子；(ii) OCA-的直接相互作用； B 具有介体共激活复合物的 MED1 亚基和 GC 特异性转录因子 (MEF2B) 对于 BCL6 表达很重要，并且 (iii) B 细胞固有的 Oca-B 依赖性对于体内 GC B 细胞分化至关重要。根据我们之前的 OCA-B 研究和最近的初步数据，我们追求主导作用 OCA-B 在 GC 形成中的作用涉及通过其远端增强子区域招募和激活 BCL6 集中转录因子和辅助因子，包括染色质/表观遗传因子，促进增强子- 我们还假设 OCA-B 在 GC 衍生的淋巴瘤发生中发挥着关键作用。为了解决这些问题，我们将通过相互作用研究（i）OCA-B的功能和作用机制与 MED1/Mediator 和 MEF2B 一起，在离体 GC B 和淋巴瘤细胞中的 BCL6 LCR/超级增强子上， (ii) OCA-B依赖性转录共激活通过严格的生物化学作用机制体外转录测定；(iii) OCA-B 在体内 GC B 细胞分化中的作用机制，包括确定关键靶基因和调控网络；(iv) OCA-B 在 B 细胞淋巴瘤进展中的作用；我们将使用互补的生化、基因组、生物信息学、遗传学、基因编辑、基于细胞和体内（小鼠模型）方法的完成将增进我们对分子的理解。 OCA-B 在 GC 特异性转录调控、GC B 细胞分化和 GC- 中的作用机制值得注意的是，它还将为治疗 B 细胞淋巴瘤的新治疗策略提供线索。细胞淋巴瘤。