Project 2: The cohesin complex as a tumor suppressor in myeloid leukemia

项目 2：粘连蛋白复合物作为骨髓性白血病的肿瘤抑制因子

• 批准号: 10153722
• 负责人: ARI M. MELNICK
• 金额: $ 41.83万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-12 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10153722
• 关键词: 3-Dimensional; Antibody Affinity; Antigen Presentation; Antigens; Apoptosis; Architecture; B cell differentiation; B-Cell Development; B-Cell Lymphomas; B-Cell Neoplasm; B-Lymphocytes; Cancer Biology; Cell Nucleus; ChIP-seq; Chromatin; Chromosome Arm; Cities; Complex; Data Set; Drug Targeting; Enhancers; Epigenetic Process; Genes; Genetic; Genetic Transcription; Genome; Genomic Instability; Genomics; Hi-C; Histones; Human; Immune response; Immunity; Immunoglobulin Somatic Hypermutation; Immunoglobulins; Knock-out; Knockout Mice; Knowledge; Lead; Lesion; Light; Link; Locus Control Region; Lymphoma; Lymphomagenesis; Malignant - descriptor; Malignant Neoplasms; Mediating; Memory; Molecular Conformation; Morphology; Mutant Strains Mice; Mutation; Myeloid Leukemia; Neighborhoods; Normal Cell; Nuclear; Oncogenic; Patients; Pharmacology; Phenotype; Pilot Projects; Plasma; Plasma Cells; Process; Proteins; Reaction; Recurrence; Resolution; Rest; Role; Signal Transduction; Somatic Mutation; Structure of germinal center of lymph node; T-Lymphocyte; Time; Transcriptional Regulation; Tumor Suppressor Proteins; base; cancer cell; cohesin; complement C4c; conditional knockout; differential expression; epigenetic regulation; experimental study; gain of function; genetic regulatory protein; genome-wide; insight; interest; large cell Diffuse non-Hodgkin' s lymphoma; loss of function; mutant; novel; plasma cell differentiation; prevent; programs; promoter; targeted treatment; transcription factor; tumor; tumor progression

SUMMARY - PROJECT 2 (MELNICK) Most B-cell lymphomas arise from germinal center (GC) B-cells, which form transiently after T-cell dependent antigen stimulation. GC B-cells undergo massive proliferation and genomic instability occurring as a byproduct of immunoglobulin somatic hypermutation, which puts them in danger of malignant transformation. The phenotypic shift from quiescent naïve B-cells to proliferative and unstable GC B-cells is massive, rapid, and involves differential expression of thousands of genes. GC B-cells are evanescent, and quickly undergo terminal differentiation to plasma cells (or undergo apoptosis) after antigen presentation. The most common B- cell lymphomas (DLBCL and FL) in essence are GC B-cells that have continued to aberrantly persist and fail to undergo terminal differentiation. We are interested in how these dramatic changes in phenotypes occur, and how this process can be corrupted to cause lymphoma. To understand the mechanistic basis of the GC B-cell phenotype we performed genome-wide chromosomal conformation capture (Hi-C, 4C) along with ChIP- seq for histone marks, cohesin and TFs at different timepoints during B-cell development. We observed truly massive shifts in chromosomal architecture in GC B-cells including but not limited to i) increased promoter connectivity, ii) formation of novel enhancer loops, iii) 5' to 3' gene looping, iv) merging of discrete boundary delimited gene neighborhoods to form larger gene “cities resulting in de novo epigenetic coordination between genes formally isolated from one another, and v) establishment of GC B-cell specific locus control regions (LCRs) that control hundreds of GC B-cell gene enhancers (Bunting et. al. Immunity 2016). Strikingly, all of these architectural changes were tightly associated with cohesin complex redistribution and notably, we observed recurrent somatic mutation or deletion of the cohesin unloading protein PDS5B in public lymphoma genomic profiling datasets. Our pilot studies suggest that PDS5B regulates genes involved in exiting the GC reaction and terminal differentiation. Preliminary experiments in PDS5b knockout or point mutant mice, point to disruption of GC dynamics and blockade of GC exit. Based on these considerations we hypothesize that PDS5B is required to unload the GC specific cohesin distribution state so that the GC B-cell transcriptional program can be extinguished and allow for a different configuration that favors plasma cell differentiation. We predict that specific signals received from GC T-cells in the GC light zone directly induce PDS5B-dependent cohesin redistribution. We propose that genetic lesions of PDS5B cause the genome to become architecturally stuck in the GC configuration thus blocking epigenetic reprogramming required for terminal differentiation and leading to malignant transformation. We hypothesize that cohesin blockade may be nonetheless reversible and targetable by drugs that can erase GC/lymphoma epigenetic programming. This proposal will thus define the role and mechanism of action of dynamic cohesin complex remodeling in the humoral immune response and lymphomagenesis, and develop novel cohesin therapy approaches.

摘要 - 项目 2（梅尔尼克） 大多数 B 细胞淋巴瘤起源于生发中心 (GC) B 细胞，这些细胞在 T 细胞依赖性后短暂形成 抗原刺激。 GC B 细胞经历大规模增殖和作为副产品出现的基因组不稳定 免疫球蛋白体细胞超突变，使它们面临恶性转化的危险。这 从静止的幼稚 B 细胞到增殖且不稳定的 GC B 细胞的表型转变是巨大的、快速的且 涉及数千个基因的差异表达。 GC B 细胞是短暂的，并且很快就会经历 抗原呈递后终末分化为浆细胞（或经历凋亡）。最常见的B- 细胞淋巴瘤（DLBCL 和 FL）本质上是持续异常存在并衰竭的 GC B 细胞 进行终末分化。我们感兴趣的是这些表型的巨大变化是如何发生的， 以及这个过程如何被破坏而导致淋巴瘤。了解 GC 的机制基础 我们对 B 细胞表型进行了全基因组染色体构象捕获 (Hi-C、4C) 以及 ChIP- B 细胞发育过程中不同时间点的组蛋白标记、粘连蛋白和 TF 的 seq。我们真实观察到 GC B 细胞染色体结构发生巨大变化，包括但不限于 i) 启动子增加 连接性，ii) 新型增强子环的形成，iii) 5' 至 3' 基因环，iv) 离散边界的合并 划定基因邻域以形成更大的基因“城市”，从而导致基因之间从头开始的表观遗传协调 基因彼此正式分离，以及 v) GC B 细胞特异性基因座控制区的建立 (LCR) 控制数百个 GC B 细胞基因增强子 (Bunting et. al. Immunity 2016)。引人注目的是，所有 这些架构变化与粘连蛋白复合体的重新分布密切相关，值得注意的是，我们 在公共淋巴瘤中观察到粘连蛋白卸载蛋白 PDS5B 的反复体细胞突变或缺失 基因组分析数据集。我们的初步研究表明 PDS5B 调节参与退出 GC 的基因 反应和终末分化。 PDS5b 敲除或点突变小鼠的初步实验，点 破坏 GC 动力学并封锁 GC 出口。基于这些考虑，我们假设 PDS5B 需要卸载 GC 特异性粘连蛋白分布状态，以便 GC B 细胞转录 程序可以被消除并允许有利于浆细胞分化的不同配置。我们 预测从 GC 光区中的 GC T 细胞接收到的特定信号直接诱导 PDS5B 依赖性 粘连蛋白重新分布。我们认为 PDS5B 的遗传损伤导致基因组在结构上变得 卡在 GC 配置中，从而阻止终末分化所需的表观遗传重编程， 导致恶变。我们假设粘连蛋白阻断可能是可逆的 并且可以通过可以消除 GC/淋巴瘤表观遗传编程的药物作为目标。因此，该提案将定义 动态粘连蛋白复合物重塑在体液免疫反应中的作用和作用机制 和淋巴瘤发生，并开发新的粘连蛋白治疗方法。