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: 10402272
• 负责人: ARI M. MELNICK
• 金额: $ 48.91万
• 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/10402272
• 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，在T细胞依赖后一过性形成 抗原刺激。作为副产品，GC B细胞经历了大规模的增殖和基因组的不稳定 免疫球蛋白的体细胞超突变，这使他们处于恶变的危险中。这个 从静止的幼稚B细胞到增殖和不稳定的GC B细胞的表型转变是巨大的、快速的和 涉及数千个基因的差异表达。GC B细胞是转瞬即逝的，并且很快就会 在抗原呈递后，向浆细胞终末分化(或发生凋亡)。最常见的B- 细胞性淋巴瘤(DLBCL和FL)本质上是持续异常存活和衰竭的GC B细胞 分化，分化经历末端分化我们感兴趣的是这些表型的巨大变化是如何发生的， 以及这个过程是如何被破坏而导致淋巴瘤的。理解GC的机理基础 B细胞表型我们进行了全基因组染色体构象捕获(Hi-C，4C)与芯片- B细胞发育过程中不同时间点的组蛋白标记物、粘附素和转录因子的SEQ。我们真的观察到了 GC B细胞染色体结构的巨大变化，包括但不限于：1)启动子增加 连通性，II)形成新的增强子环，III)5‘到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”，导致从头开始表观遗传协调 正式分离的基因，以及v)建立GC B细胞特异性基因座控制区 (LCR)，控制数百个GC B细胞基因增强子(Bunting et.艾尔豁免权2016年)。令人惊讶的是，所有 这些结构变化与粘附素复合体的重新分布密切相关，值得注意的是，我们 公共淋巴瘤中粘附素卸载蛋白Pds5B的复发性体细胞突变或缺失 基因组图谱数据集。我们的初步研究表明，Pds5B调节与退出GC有关的基因 反应和终末分化。Pds5B基因敲除或点突变小鼠的初步实验 扰乱GC动力学，封锁GC出口。基于这些考虑，我们假设 Pds5B需要卸载GC特有的粘附素分布状态，以便GC B细胞转录 程序可以被取消，并允许不同的配置，有利于浆细胞分化。我们 预测从GC光区GC T细胞接收到的特定信号直接诱导Pds5B依赖 粘附素重新分布。我们认为，Pds5B的遗传损伤导致基因组结构上的改变 滞留在GC配置中，从而阻止末端分化所需的表观遗传重新编程 导致恶变。我们假设粘附素的阻断是可逆的。 并且是可以消除GC/淋巴瘤表观遗传编程的药物的靶点。因此，这项提案将界定 动态粘连蛋白复合体重构在体液免疫反应中的作用及机制 和淋巴增生症，并开发新的粘附素治疗方法。