Mechanisms of lineage plasticity revealed by YY1 deficiency.

YY1 缺陷揭示的谱系可塑性机制。

基本信息

批准号：
10620173
负责人：
Michael Lee Atchison
金额：
$ 50.71万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-06-01 至 2026-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10620173
关键词：
B-Lymphocytes Basophils Binding Bone Marrow CD8-Positive T-Lymphocytes Cell Lineage Cells Chromatin Chromatin Structure Coupled DNA DNA Binding Data Defect Development Enabling Factors Epigenetic Process Exhibits Gene Expression Gene Expression Profile Genes Genetic Transcription Hematopoietic Hematopoietic stem cells Heterochromatin Immune In Vitro Laboratories Lewis lung carcinoma cell Lymphoid Macrophage Mediating Molecular Molecular Genetics Molecular Profiling Mus Null Lymphocytes Pathway interactions Pattern Peptide Initiation Factors Phenotype Process Regulation Repression Role Signal Transduction Structure System T-Lymphocyte Therapeutic Uses Transcriptional Regulation YY1 Transcription Factor conditional knockout developmental plasticity eosinophil experimental study genomic locus in vivo monocyte neutrophil notch protein progenitor recruit stem cells transcription factor transdifferentiation

项目摘要

Hematopoietic development is an ordered process in which stem cells give rise to multiple lineages. While early progenitors can be multipotent, lineage-specific progenitors reach a stage where they become exclusively committed to that lineage. For example, B and T cell lineages differentiate from lymphoid-primed progenitors produced in the bone marrow, and exclusive commitment to the B cell lineage occurs as cells transition from the pre-pro-B to the pro-B cell stage. Despite the commitment of pro-B cells to the B lineage, we have made the surprising discovery that conditional knock-out of the ubiquitous multi-functional transcription factor YY1 in pro-B cells, results in the loss of B lineage commitment and the consequent ability to develop into the T cell lineage both in vitro and in vivo. To understand the mechanistic basis for this surprising lineage plasticity, we have developed a new lineage tracing mouse line that will enable us to determine how YY1-null pro-B cells develop into T lineage cells (de-differentiation to more primitive progenitors, or trans-differentiation), assess the potential for YY1- null pro-B cells to develop into other hematopoietic lineages, and determine if YY1-null T cells also exhibit lineage plasticity (Aim 1). Mechanistically, lineage-specific transcription factors bind to DNA and regulate gene expression prior to subsequent large-scale alterations in chromatin structure needed for lineage commitment. Rigorous studies by our laboratory as well as others indicate that despite its ubiquitous expression pattern, YY1 controls long-range chromatin interactions (LRCIs) in a lineage- specific fashion. Our findings support the hypothesis that DNA binding by lineage-specific transcription factors enables YY1 recruitment to distinct genomic loci, thereby enabling YY1 to both generate LRCIs that stabilize lineage-appropriate gene expression, and to generate repressive chromatin marks (H3K27me3) at lineage-inappropriate genes. We will thus, compare the molecular genetic phenotype (gene expression patterns, chromatin accessibility, epigenetic structure, and chromatin folding) of YY1- null pro-B cells developed into DN1, DN2a, DN2b, DN3, DP, CD4+, and CD8+ T cells, compared to wild- type T lineage cells, as well as YY1 conditional knockout T lineage cells (Aim 2). We hypothesize that in the absence of YY1, T lineage development can proceed, but LRCIs needed to stably maintain lineage- specific gene expression, and heterochromatin needed for repression of alternative lineages will fail to fully develop, potentially enabling continuing lineage plasticity. Our experiments may reveal a common mechanism for controlling lineage plasticity, vastly expanding potential applicability of directing YY1-null cells into multiple lineages.

造血发育是一个有序的过程，其中干细胞产生多个谱系。虽然早期祖细胞可能是多能的，但谱系特异性祖细胞达到了一个阶段：完全致力于该血统。例如，B 细胞和 T 细胞谱系分化为骨髓中产生的淋巴引发的祖细胞，并且专门致力于 B 细胞当细胞从前原 B 细胞阶段过渡到原 B 细胞阶段时，谱系就会发生。尽管做出了承诺亲B细胞转变成B谱系，我们有了令人惊讶的发现，条件性敲除原 B 细胞中普遍存在的多功能转录因子 YY1，导致 B 谱系丧失定型以及随后在体外和体内发育成 T 细胞谱系的能力。到了解这种令人惊讶的谱系可塑性的机制基础，我们开发了一种新的谱系追踪小鼠细胞系，使我们能够确定 YY1 缺失的亲 B 细胞如何发育成 T 谱系细胞（去分化为更原始的祖细胞，或转分化），评估 YY1- 的潜力无效的 pro-B 细胞发育成其他造血谱系，并确定 YY1 无效的 T 细胞是否也表现出谱系可塑性（目标 1）。从机制上讲，谱系特异性转录因子与 DNA 结合并在随后大规模改变染色质结构所需的基因表达之前调节基因表达血统承诺。我们的实验室以及其他实验室的严格研究表明，尽管它 YY1 普遍存在的表达模式控制谱系中的长程染色质相互作用 (LRCI) 具体的时尚。我们的研究结果支持以下假设：DNA 通过谱系特异性转录结合因子使 YY1 招募到不同的基因组位点，从而使 YY1 能够生成 LRCI 稳定谱系适当的基因表达，并产生抑制性染色质标记（H3K27me3）在谱系不合适的基因上。因此，我们将比较分子遗传表型 YY1-（基因表达模式、染色质可及性、表观遗传结构和染色质折叠）与野生型相比，无效的 pro-B 细胞发育为 DN1、DN2a、DN2b、DN3、DP、CD4+ 和 CD8+ T 细胞型 T 谱系细胞，以及 YY1 条件敲除 T 谱系细胞（目标 2）。我们假设在缺乏YY1，T谱系发育可以继续进行，但LRCI需要稳定维持谱系- 特定的基因表达，以及抑制替代谱系所需的异染色质将无法充分发展，有可能实现持续的谱系可塑性。我们的实验可能揭示一个共同点控制谱系可塑性的机制，极大扩展了指导 YY1-null 的潜在适用性细胞分化成多个谱系。