How CHAF1B maintains cell state by repressing transcription of fate genes

CHAF1B 如何通过抑制命运基因的转录来维持细胞状态

• 批准号: 10271523
• 负责人: Andrew Volk
• 金额: $ 39.75万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-15 至 2026-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10271523
• 关键词: Affect; Automobile Driving; Binding; Cell Cycle; Cell Differentiation process; Cell division; Cells; Chromatin; Chromatin Modeling; Complex; DNA; DNA replication fork; Differentiated Gene; Disease; Enhancers; Epigenetic Process; Floods; Gene Activation; Gene Expression; Genes; Genetic Diseases; Genetic Transcription; Goals; Histone H3; Homeostasis; Knowledge; Link; Malignant Neoplasms; Modeling; Mutate; Pancytopenia; Phenotype; Replication-Associated Process; Reporting; Role; S Phase; Tissues; Transcription Repressor; Transcriptional Regulation; Up-Regulation; chromatin assembly factor I; chromatin protein; gene repression; human disease; novel; promoter; protein complex; recruit; stem cells; tool; transcription factor

PROJECT SUMMARY: Comprehensive regulation of transcription is a major mechanism by which immature cells functionally determine their identity. The epigenetic factors responsible for this transcriptional regulatory activity are some of the most potent, and most commonly mutated, factors implicated in tissue homeostasis and disease. We understand the role of many epigenetic factors responsible for activating transcription, but we have a limited understanding of the factors that repress transcription associated with differentiation. Additionally, we know many of the epigenetic transcriptional regulators present on the chromatin before and after replication, but we have a limited understanding of how these factors interact during replication. The relative lack of understanding of how the replication machinery regulates transcription associated with cell identity is a key knowledge gap in the field of epigenetics. Our studies suggest that the Chromatin Assembly Factor 1 (CAF1) complex, functioning in its canonical role of replication-linked chromatin assembly, is the critical factor responsible for directly regulating fate-specific transcription during replication. CAF1 is a heterotrimeric protein complex responsible for facilitating histone H3/H4 heterodimer assembly at the replication fork during the S phase of cell cycle. Our lab focuses on the functional contributions of CAF1 through studying its p60 subunit: Chromatin Assembly Factor 1B (CHAF1B). We are using CHAF1B as a model for CAF1 function because of the abundance of tools and expertise we have generated to study CHAF1B and the overwhelming evidence that readouts of CHAF1B and the CAF1 complex are functionally identical. CHAF1B is highly expressed in uncommitted stem cells, and its expression decreases as cells differentiate. We recently reported that CHAF1B directly binds chromatin at promoters and enhancers of differentiation genes, repressing their expression by blocking transcription factor binding. Depletion of CHAF1B in independent models led to massive upregulation of gene activation caused by transcription factors flooding regions of chromatin previously occupied by CHAF1B. This led to our hypothesis: CHAF1B is a master regulator of cell identity through a novel role as transcriptional repressor of fate genes in immature cells. Our long-term goal is to understand how cells regulate transcription associated with cell fate throughout differentiation. Our short-term goal is to understand how the chromatin assembly machinery affects transcriptional repression of fate genes in immature cells. In this proposal we will study the functional roles of the factors responsible for CHAF1B direct binding to chromatin on transcription and phenotype (Focus 1), and the contributions of the DNA/protein complexes recruited by CHAF1B to the chromatin on transcription and phenotype (Focus 2). Discoveries about CHAF1B, the CAF1 complex, and the larger DNA/protein chromatin landscape it promotes, have the potential for driving sweeping changes in the way we understand functional epigenetics and treat disease.

项目概要： 转录的综合调控是未成熟细胞发挥功能的主要机制 确定他们的身份。负责这种转录调节活性的表观遗传因素有一些 与组织稳态和疾病有关的最有效、最常见突变的因素。我们 了解许多负责激活转录的表观遗传因素的作用，但我们的了解有限 了解抑制与分化相关的转录的因素。另外，我们知道 许多表观遗传转录调节因子在复制前后存在于染色质上，但我们 对这些因素在复制过程中如何相互作用的了解有限。相对缺乏了解 复制机制如何调节与细胞身份相关的转录是一个关键的知识缺口 在表观遗传学领域。我们的研究表明染色质组装因子 1 (CAF1) 复合物， 发挥其复制相关染色质组装的典型作用，是负责 直接调节复制过程中的命运特异性转录。 CAF1 是一种异源三聚体蛋白复合物，负责促进组蛋白 H3/H4 异二聚体 细胞周期 S 期复制叉处的组装。我们的实验室专注于功能贡献 通过研究 CAF1 的 p60 亚基：染色质组装因子 1B (CHAF1B)。我们正在使用 CHAF1B 作为 CAF1 功能的模型，因为我们拥有丰富的工具和专业知识来研究 CHAF1B 以及 CHAF1B 和 CAF1 复合物的读数在功能上具有压倒性的证据 完全相同的。 CHAF1B在未定型干细胞中高表达，随着细胞的生长，其表达量降低 区分。我们最近报道 CHAF1B 直接结合染色质的启动子和增强子 分化基因，通过阻断转录因子结合来抑制其表达。 CHAF1B 的耗尽 在独立模型中，转录因子泛滥导致基因激活大量上调 先前被 CHAF1B 占据的染色质区域。这导致了我们的假设：CHAF1B 是大师 通过在未成熟细胞中作为命运基因转录抑制因子的新作用来调节细胞身份。 我们的长期目标是了解细胞如何调节与细胞命运相关的转录 整个分化。我们的短期目标是了解染色质组装机制如何 影响未成熟细胞中命运基因的转录抑制。在本提案中，我们将研究功能 负责 CHAF1B 直接结合染色质的因子对转录和表型的作用（焦点 1)，以及 CHAF1B 招募的 DNA/蛋白质复合物对转录染色质的贡献 和表型（焦点 2）。关于 CHAF1B、CAF1 复合物和更大的 DNA/蛋白质的发现 它所促进的染色质景观有可能推动我们理解方式的彻底改变 功能性表观遗传学和治疗疾病。