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: 10652281
• 负责人: ARI M. MELNICK
• 金额: $ 40.43万
• 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/10652281
• 关键词: 3-Dimensional; Antibody Affinity; Antigen Presentation; Antigens; Apoptosis; Architecture; B cell differentiation; B-Cell Development; B-Cell Lymphomas; B-Lymphocytes; Cancer Biology; Cell Nucleus; ChIP-seq; Chromatin; Chromosome Arm; Cities; Complex; Data Set; Enhancers; Epigenetic Process; Genes; Genetic; Genetic Transcription; Genome; Genomic Instability; Genomics; Hi-C; Histones; Human; Immune response; Immunity; Immunoglobulin Somatic Hypermutation; Knock-out; Knockout Mice; Knowledge; 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; Pharmaceutical Preparations; Phenotype; Pilot Projects; Plasma Cells; Process; Proliferating; Proteins; Reaction; Recurrence; Repression; Resolution; Rest; Role; Signal Transduction; Somatic Mutation; Structure of germinal center of lymph node; T-Lymphocyte; Time; Transcriptional Regulation; Tumor Suppressor Proteins; cancer cell; cohesin; 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; pharmacologic; 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细胞淋巴瘤来自生发中心（GC）B细胞，它们在T细胞依赖性后瞬时形成 抗原刺激。 GC B细胞经历大规模的增殖和基因组不稳定性作为副产品 免疫球蛋白体细胞超昂贵，这使它们处于恶性转化的危险中。这 从静止的幼稚的B细胞到增殖和不稳定的GC B细胞的表型转移是巨大的，快速的，并且 涉及数千个基因的差异表达。 GC B细胞均匀，迅速发生 抗原表现后，末端分化与浆细胞（或经历凋亡）。最常见的b- 细胞淋巴瘤（DLBCL和FL）本质上是GC B细胞，持续持久并失败 进行终端分化。我们对表型的这些戏剧性变化如何感兴趣， 以及如何损坏该过程以引起淋巴瘤。了解GC的机械基础 B细胞表型，我们进行了全基因组染色体构象捕获（HI-C，4C）以及芯片 B细胞发育过程中不同时间点的组蛋白标记，粘蛋白和TF的SEQ。我们确实观察到了 GC B细胞中染色体体系结构的大规模转变，包括但不限于I）增加的启动子 连通性，ii）新型增强子循环的形成，iii）5'至3'基因循环，iv）离散边界合并 划界基因邻域形成了更大的基因“导致从头表观遗传协调的城市 正式分离的基因，v）建立GC B细胞特异性基因座控制区域 （LCR）控制数百个GC B细胞基因增强子（Bunting etal。Mysterity2016）。令人惊讶的是，全部 这些建筑变化与粘蛋白复合物的重新分布密切相关，值得注意的是，我们 观察到的复发性体细胞突变或公共淋巴瘤中粘着蛋白PDS5B的粘着蛋白的脱失 基因组分析数据集。我们的试点研究表明，PDS5B调节与GC退出有关的基因 反应和末端分化。 PDS5B敲除或点突变小鼠的初步实验，点 破坏GC动力学和GC出口的阻塞。基于这些考虑因素，我们假设 需要PDS5B卸载GC特异性粘着蛋白分布态，以便GC B细胞转录 可以扩展程序，并允许采用有利于浆细胞分化的不同配置。我们 预测从GC光区中从GC T细胞收到的特定信号直接影响PDS5B 粘素再分配。我们建议PDS5B的遗传病变导致基因组成为建筑 卡在GC构型中，从而阻止终端分化和 导致恶性转变。我们假设粘素阻断可能仍然是可逆的 并由可以擦除GC/淋巴瘤表观遗传程序的药物进行靶向。因此，该建议将定义 动态粘着素复合物重塑在体液免疫反应中的作用和机制 和淋巴作用，并开发新型的粘着素治疗方法。