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.

项目摘要 自我更新和多能性是胚胎干细胞（ESC）的定义属性。虽然极 这些细胞在体内是短暂的，可以从胚胎的内细胞团中捕获并无限期地维持 处于多能状态或在体外分化成基本上任何特化的细胞。胚胎干细胞 干细胞（ESCs）为再生医学带来了巨大的希望，再生医学试图利用ESCs再生或 使因损伤、疾病或潜在基因突变而受损的细胞和组织恢复活力。 然而，为了充分利用它们的潜力，我们必须了解控制ESC自我更新的机制 和多能性以允许任何组织的（再生），同时防止茎的异常生长或消耗 细胞池干细胞身份由主调节因子OCT 4决定的基因调节网络定义， SOX 2和NANOG。然而，这些转录因子的结合反过来又高度依赖于转录因子。 染色质景观的可及性。为了获取潜在的基因组信息，组蛋白必须 重新定位或移除，这是由ATP依赖性染色质重塑复合物执行的功能。 特别是，哺乳动物SWI/SNF或BAF复合物的几种组分对于形成 内细胞团和用于体外衍生ESCs。BAF复合物由组合的 来自基因家族的同源亚基的组装。然而，目前还没有一种机械化的 理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 生物化学方法，一个完全新的和以前未描述的形式的BAF复合物， 在ESCs中发现了含有乙酰赖氨酸阅读器的Bromodomain-containing蛋白9（BRD 9）。由于 BRD 9和其他独特亚基的掺入，含有BRD 9的BAF复合物或“BBAF复合物”， 在整个基因组中具有独特的靶向作用，并表现出特异性的调节相互作用， 典型的BAF复合物。此外，BBAF复合物缺乏某些对ATP至关重要的亚基。 依赖染色质重塑，表明它可能具有替代功能。未来五年的目标 多年来，研究人员正在确定BRD 9介导的染色质靶向BBAF复合物的机制，以及如何 其涉及ESC自我更新和多能性中涉及的基因的转录调节。这些 研究将有助于我们了解BAF复杂的异质性如何有助于精确控制 ESC转录程序，并提供了一个框架，了解个人的BAF的作用 BAF复合物的细胞类型和发育阶段特异性功能的亚基。