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: 9754199
• 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/9754199
• 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; Stem cells; Tissues; Transcriptional Regulation; cell type; chromatin remodeling; combinatorial; embryonic stem cell; epigenetic regulation; in vivo; novel; pluripotency; prevent; programs; self-renewal; 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.

项目总结 自我更新和多能性是胚胎干细胞(ESC)的特征。虽然非常 在体内，这些细胞可以从胚胎的内细胞团中被捕获并无限期地保持 处于多能状态或在体外基本上分化为任何特化细胞。因此，胚胎干细胞 细胞(ESCs)为再生医学带来了巨大的希望，该医学试图利用ESCs来再生或 使因受伤、疾病或潜在的基因突变而受损的细胞和组织恢复活力。 然而，为了充分发挥其潜力，我们必须了解控制ESC自我更新的机制 和多能性，以允许(重新)生成任何组织，同时防止茎的异常生长或枯竭 牢房池。干细胞身份由主调节子OCT4规定的基因调控网络定义， SOX2和NANOG。然而，这些转录因子的结合反过来又高度依赖于 染色质景观的可访问性。为了获得潜在的基因组信息，组蛋白必须 被重新定位或移除，这一功能是由依赖于ATP的染色质重塑复合体执行的。 特别是，哺乳动物SWI/SNF或BAF复合体的几个成分对于形成 取内细胞团，用于胚胎干细胞的体外分化。BaF复合体受组合体的调节 来自基因家族的同源亚基的组装。然而，目前还没有机械性的 了解不同亚基的独特组合如何影响BAF复合体的靶向性或功能。vbl.使用 生化方法，一种全新的和以前未描述的BAF复合体形式是 在含有乙酰赖氨酸阅读器的ESCs中发现了含有溴域的蛋白9(BRD9)。由于 结合BRD9和其他独特的亚基，含有BRD9的BAF复合体或‘BBAF复合体’是 在基因组中具有独特的靶向性，并表现出未发现的与 典型的生物滤池复合体。此外，BBAF复合体缺乏对ATP至关重要的某些亚基- 依赖染色质重塑，提示其可能具有交替功能。未来五年的目标 几年后将确定BRD9介导的染色质靶向BBAF复合体的机制以及如何 这与胚胎干细胞自我更新和多能性相关基因的转录调控有关。这些 研究将有助于我们理解曝气生物滤池复杂的异质性如何有助于精确控制 ESC转录程序，并为理解单个BAF的作用提供了一个框架 亚基在BAF复合体的细胞类型和发育阶段特异性功能中的作用。