Epigenetic regulation of embryonic stem cells by ATP-dependent BAF chromatin remodeling complexes

ATP依赖性BAF染色质重塑复合物对胚胎干细胞的表观遗传调控

• 批准号: 9980939
• 负责人: Diana Clare Hargreaves
• 金额: $ 48.1万
• 依托单位: SALK INSTITUTE FOR BIOLOGICAL STUDIES
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9980939
• 关键词: Affect; Binding; Biochemical; Bromodomain; Cells; Chromatin; Chromatin Remodeling Factor; Complex; DNA Sequence Alteration; Derivation procedure; Development; Disease; Disease model; Embryo; Epigenetic Process; Exhibits; Gene Expression Regulation; Gene Family; Generations; Genes; Genetic Transcription; Genome; Genomics; Goals; Growth; Heterogeneity; Histones; In Vitro; Individual; Injury; Inner Cell Mass; Knowledge; Lysine; Mediating; Natural regeneration; Organism; Property; Proteins; Reader; Regenerative Medicine; Regulator Genes; Research; Role; Tissues; Transcriptional Regulation; cell type; chromatin remodeling; combinatorial; embryonic stem cell; epigenetic regulation; in vivo; novel; pluripotency; prevent; programs; self-renewal; stem cells; transcription factor

PROJECT SUMMARY Self-renewal and pluripotency are defining properties of an embryonic stem cell (ESC). Although extremely transient in vivo, these cells can be captured from the inner cell mass of the embryo and maintained indefinitely in a pluripotent state or differentiated into essentially any specialized cell in vitro. As such, embryonic stem cells (ESCs) hold great promise for regenerative medicine, which seeks to use ESCs to regenerate or rejuvenate cells and tissues that have been damaged due to injury, disease, or underlying genetic mutations. However, to leverage their full potential, we must understand the mechanisms that control ESC self-renewal and pluriptency to allow (re)generation of any tissue while preventing aberrant growth or depletion of the stem cell pool. Stem cell identity is defined by a gene regulatory network dictated by the master regulators OCT4, SOX2 and NANOG. However, the binding of these transcriptional factors is in turn highly dependent on the accessibility of the chromatin landscape. To access the underlying genomic information, histone proteins must be repositioned or removed, a function that is performed by ATP-dependent chromatin remodeling complexes. In particular, several components of the mammalian SWI/SNF or BAF complex are essential for formation of the inner cell mass and for derivation of ESCs in vitro. BAF complexes are regulated by the combinatorial assembly of homologous subunits from gene families. However, there is currently no mechanistic understanding of how unique combinations of distinct subunits affect BAF complex targeting or function. Using biochemical approaches, a completely novel and previously undescribed form of the BAF complex was discovered in ESCs that contains the acetyl lysine reader, Bromodomain-containing protein 9 (BRD9). Due to the incorporation of BRD9 and other unique subunits, the BRD9-containing BAF complex or 'BBAF complex' is uniquely targeted across the genome and exhibits specific regulatory interactions not found associated with canonical BAF complexes. Moreover, the BBAF complex lacks certain subunits that are critical for ATP- dependent chromatin remodeling, suggesting that it may have alternate function. The goals for the next five years are to determine the mechanism of BRD9-mediated chromatin targeting of the BBAF complex and how that relates to the transcriptional regulation of genes involved in ESC self-renewal and pluripotency. These studies will aid in our understanding of how BAF complex heterogeneity contributes to the precise control of the ESC transcriptional program and provide a framework for understanding the roles of individual BAF subunits in contributing to cell type- and developmental stage-specific function of BAF complexes.

项目摘要 自我更新和多能性是定义胚胎干细胞（ESC）的特性。虽然非常 在体内瞬态，这些细胞可以从胚胎的内部细胞质量捕获，并无限期地保持 在多能状态下或在体外分化为任何专门的细胞。因此，胚胎茎 细胞（ESC）对再生医学具有巨大的希望，该医学试图使用ESC再生或 因损伤，疾病或潜在的基因突变而损害的细胞和组织。 但是，要利用它们的全部潜力，我们必须了解控制自我更新的机制 并多元化允许（重新）在防止异常生长或枯竭的同时（重新）生成任何组织 细胞池。干细胞身份由由主调节器Oct4决定的基因调节网络定义 Sox2和Nanog。但是，这些转录因子的结合又高度依赖于 染色质景观的可及性。要访问潜在的基因组信息，组蛋白必须 重新定位或去除，这是由ATP依赖性染色质重塑复合物执行的函数。 特别是，哺乳动物SWI/SNF或BAF复合物的几个组成部分对于形成至关重要 内部细胞质量和体外ESC的推导。 BAF复合物由组合调节 来自基因家族的同源亚基的组装。但是，目前没有机械 了解不同亚基的独特组合如何影响BAF复合物靶向或功能。使用 生化方法是一种完全新颖且以前未描述的BAF复合物的形式 在ESC中发现的，其中包含乙酰赖氨酸读取器，含溴脱域的蛋白9（BRD9）。由于 BRD9和其他独特亚基的结合，含BRD9的BAF复合物或“ BBAF综合体”是 独特针对整个基因组的目标，并表现出与 规范BAF复合体。此外，BBAF综合体缺乏某些对ATP至关重要的亚基 依赖性染色质重塑，表明它可能具有替代功能。接下来的五个目标 多年是确定BBAF复合物的BRD9介导的染色质靶向的机理以及如何 这与ESC自我更新和多能涉及的基因的转录调控有关。这些 研究将有助于我们理解BAF复合异质性如何有助于精确控制 ESC转录程序，并提供了理解单个BAF角色的框架 促进BAF复合物的细胞类型和发育阶段特异性功能的亚基。