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.

项目总结： 转录的全面调控是未成熟细胞功能发挥的主要机制 确定他们的身份。导致这种转录调控活动的表观遗传因素有以下几点 与组织动态平衡和疾病有关的最有效、最常见的突变因子。我们 了解许多负责激活转录的表观遗传因子的作用，但我们有一个有限的 了解与分化相关的抑制转录的因素。另外，我们知道 许多表观遗传转录调控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是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)复合体， 发挥其典型作用的复制连接染色质组装，是负责的关键因素 在复制过程中直接调控命运特异的转录。 CAF1是一种促进组蛋白H3/H4异源二聚体的异源三聚体蛋白复合体 在细胞周期的S阶段，在复制叉处组装。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)。我们使用的是CHAF1B 作为CAF1功能的模型，因为我们已经生成了丰富的工具和专业知识来研究 CHAF1B和CHAF1B和CAF1复合体读数具有功能性的压倒性证据 一模一样。CHAF1B在未承诺的干细胞中高表达，其表达随着细胞的增加而降低 差异化。我们最近报道了CHAF1B直接与染色质结合在启动子和增强子上 分化基因，通过阻断转录因子结合来抑制其表达。CHAF1B的耗竭 在独立模型中，转录因子泛滥导致基因激活大量上调 之前被CHAF1B占据的染色质区域。这导致了我们的假设：CHAF1B是一个大师 通过在未成熟细胞中作为命运基因转录抑制因子的新角色来调节细胞特性。 我们的长期目标是了解细胞如何调控与细胞命运相关的转录 整个分化过程中。我们的短期目标是了解染色质组装机器是如何 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 CHAF1B直接与染色质结合的因子在转录和表型上的作用(焦点 1)，以及CHAF1B招募的DNA/蛋白质复合体对染色质转录的贡献 表型(焦点2)。关于CHAF1B、CAF1复合体和更大的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的方式发生彻底的变化 功能性表观遗传学和治疗疾病。