Histone chaperones and cell state regulation

组蛋白伴侣和细胞状态调节

• 批准号: 10886880
• 负责人: Amanda Rietta Wasylishen
• 金额: $ 47.09万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10886880
• 关键词: ATRX gene; Affect; Alleles; Binding; Biology; Cells; Chromatin; Code; Complex; Coupled; DAXX gene; DNA Structure; Data; Deposition; Diabetes Mellitus; Disease; Duct (organ) structure; Embryo; Endogenous Retroviruses; Epigenetic Process; Epithelial Cells; Equilibrium; Foundations; Frequencies; Future; Gene Expression; Genes; Genetic; Genetic Models; Genetic Transcription; Genome; Goals; Hematopoietic; Hematopoietic stem cells; Heterochromatin; Histologic; Histone H3; Histones; Homeostasis; Human; Human Genome; Impairment; In Vitro; Individual; Investigation; Islet Cell Tumor; Knowledge; Lead; Lesion; Link; Maintenance; Malignant Neoplasms; Mediating; Mediator; Metaplasia; Modeling; Molecular; Molecular Chaperones; Mus; Mutation; Normal tissue morphology; Organ; Pancreas; Pancreatic Injury; Pancreatitis; Pathogenicity; Pathologic; Phenotype; Physiological; Proteins; Recovery; Recurrence; Regenerative response; Regulation; Regulatory Element; Repression; Research; Role; Somatic Mutation; Stress; Time; Tumor Suppression; Variant; Work; derepression; embryo tissue; epigenetic regulation; epigenome; epigenomic profiling; epigenomics; human embryonic stem cell; in vivo; in vivo regeneration; induced pluripotent stem cell; infancy; injury and repair; innovation; insight; loss of function mutation; mouse model; mutant; physiologic model; postnatal; programs; protein protein interaction; regenerative; response; response to injury; stem cell model; tissue injury; tissue repair; transcriptome; transcriptomic profiling; transcriptomics; tumorigenesis

Modified Project Summary/Abstract Section Homeostasis represents an essential balance between adjusting to changing conditions and maintaining overall stability, with perturbations contributing to diseases including diabetes, pancreatitis and cancers. Epigenetic mechanisms are central to homeostasis, including histone variants and the chaperone complexes that mediate their deposition. Histone 3.3 (H3.3) is a replacement variant for canonical histone H3 and is deposited in heterochromatin by a complex containing DAXX and ATRX. The importance of this epigenetic regulatory axis is emphasized by the early embryonic lethality of mice when any component is deleted, and recurrent somatic mutations in human cancers. This includes mutually exclusive loss-of-function mutations in DAXX or ATRX in 43% of pancreatic neuroendocrine tumors. The understanding of the physiologic functions of this regulatory complex and its component parts remains in its infancy. Emerging evidence indicates individual components regulate cellular differentiation states, including contributing to the establishment and maintenance of induced pluripotent stem cells in vitro and safeguarding hematopoietic stem cells against inappropriate differentiation in vivo. Recent work by the PI demonstrates that Daxx restricts cellular plasticity in the pancreas and maintains endogenous retroviral (ERV) silencing in vivo. This leads to the central hypothesis: As a regulator of H3.3 and heterochromatin, Daxx enforces a robust chromatin landscape that is important for the maintenance of transcriptional states and differentiation programs. The proposed studies in this project will combine comprehensive molecular and cellular analysis to dissect how Daxx regulates the epigenome, impacts gene expression, and contributes to physiologic cell state. This project will: Define Daxx-dependent regulation of the epigenome in vivo (Aim 1); and Elucidate Daxx-dependent cell state changes in a time course of pancreatic injury and recovery in vivo (Aim 2). Two new mouse models have recently been generated by the PI that abrogate the Daxx:Atrx and Daxx:H3.3 interactions respectively and subsequent studies will incorporate these innovative separation-of-function alleles to further dissect the DAXX/ATRX/H3.3 axis. Additionally, as mounting data suggests ERV repression is an important physiological function of Daxx and acknowledging the differences in repeat genomes between species, the proposed work will determine how DAXX loss affects transcriptional and cell state programs in the context of a human genome (Aim 3). Collectively, this project proposes an innovative research program that integrates powerful genetic models with comprehensive epigenomic and transcriptomic profiling to provide direct mechanistic insight into how the Daxx/Atrx/H3.3 complex contributes to chromatin maintenance and dynamics, and how perturbations impact downstream transcriptional and phenotypic states. Collectively, this work contributes to the project’s long-term goal of understanding the molecular mechanisms that maintain cellular identity and homeostasis, and the downstream pathological consequences when these mechanisms are lost.

修改项目摘要/摘要部分 稳态代表了适应不断变化的条件和保持整体稳定之间的基本平衡，扰动有助于疾病，包括糖尿病，胰腺炎和癌症。表观遗传机制是稳态的核心，包括组蛋白变体和介导其沉积的伴侣复合物。组蛋白3.3（H3.3）是典型组蛋白H3的替代变体，并且通过含有DAXX和ATRX的复合物沉积在异染色质中。这种表观遗传调控轴的重要性是强调了早期胚胎小鼠的致死性时，任何组件被删除，并在人类癌症的复发性体细胞突变。这包括43%的胰腺神经内分泌肿瘤中DAXX或ATRX的互斥功能丧失突变。对这种调节复合物及其组成部分的生理功能的理解仍处于起步阶段。新出现的证据表明，单个组分调节细胞分化状态，包括有助于体外诱导多能干细胞的建立和维持，以及保护造血干细胞免于体内不适当的分化。PI最近的工作表明，Daxx限制胰腺中的细胞可塑性，并在体内维持内源性逆转录病毒（ERV）沉默。这导致了中心假设：作为H3.3和异染色质的调节剂，Daxx实施了一个强大的染色质景观，这对维持转录状态和分化程序很重要。该项目中的拟议研究将联合收割机结合全面的分子和细胞分析，以剖析Daxx如何调节表观基因组，影响基因表达，并有助于生理细胞状态。该项目将：定义体内表观基因组的Daxx依赖性调节（目标1）;阐明体内胰腺损伤和恢复时程中Daxx依赖性细胞状态的变化（目标2）。PI最近生成了两种新的小鼠模型，分别消除了Daxx：Atrx和Daxx：H3.3相互作用，后续研究将纳入这些创新的功能分离等位基因，以进一步剖析DAXX/ATRX/H3.3轴。此外，随着越来越多的数据表明ERV抑制是Daxx的一个重要生理功能，并承认物种之间重复基因组的差异，拟议的工作将确定DAXX损失如何影响人类基因组背景下的转录和细胞状态程序（目标3）。总的来说，该项目提出了一个创新的研究计划，将强大的遗传模型与全面的表观基因组和转录组分析相结合，以提供直接的机制洞察Daxx/Atrx/H3.3复合物如何有助于染色质的维持和动态，以及扰动如何影响下游转录和表型状态。总的来说，这项工作有助于该项目的长期目标，即理解维持细胞身份和稳态的分子机制，以及当这些机制丢失时的下游病理后果。