Role of embryonic multipotent progenitors in hematopoietic ageing

胚胎多能祖细胞在造血衰老中的作用

• 批准号: 10154848
• 负责人: Michael Ian Quach
• 金额: $ 6.56万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-31 至 2023-07-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10154848
• 关键词: ATAC-seq; Ablation; Adult; Age; Aging; Biological Assay; Blood; Blood Cells; Bone Marrow; Cardiovascular Diseases; Cardiovascular system; Cause of Death; Cell Compartmentation; Cells; Chromatin; Chronic; Data; Defect; Deterioration; Development; Disease; Drops; Elderly; Embryo; Embryo Loss; Embryonic Development; Epigenetic Process; Equilibrium; Etiology; Exclusion; Fetal Development; Generations; Genes; Genetic; Genetic Transcription; Goals; Growth; Health; Healthcare Systems; Hematology; Hematopoiesis; Hematopoietic; Hematopoietic System; Hematopoietic stem cells; Human; Immune; Individual; Inflammaging; Inflammation; Label; Lead; Life; Longevity; Lymphocyte; Lymphoid; Lymphoid Cell; Lymphopoiesis; Modeling; Molecular Analysis; Multipotent Stem Cells; Mus; Myelogenous; Myeloproliferative disease; Older Population; Phenotype; Population; Predisposition; Production; Risk; Role; Source; System; Techniques; Testing; Thrombosis; Transcript; Translating; Transplantation; Up-Regulation; Ursidae Family; Work; adaptive immunity; age related; aged; differential expression; embryo cell; hematopoietic stem cell expansion; hemogenic endothelium; high risk; infection rate; infection risk; insight; leukemia; novel; overexpression; progenitor; screening; self-renewal; stem cell population; stem cells; thrombotic; tool; transcriptome sequencing; transcriptomics; treatment strategy; young adult

Project Summary/Abstract In humans, aging is associated with chronic inflammation and a decline in adaptive immunity, leading to higher rates of infection and cardiovascular disease, two of the leading causes of death in adults over 65. These hematologic defects are due in part to deficiencies in aged hematopoiesis, which is biased toward myeloid lineages. Many studies on aged hematopoiesis rely on transplantation assays or isolation of specific hematopoietic stem cell (HSC) populations for molecular analysis. While these studies highlight important features of aged HSCs, their approaches focus on long-term (LT) HSCs, a small subset of hematopoietic cells, often to the exclusion of other progenitor populations. Recent studies employ inducible genetic tags to track unperturbed native hematopoiesis. Many of these studies suggest that a large number of progenitor clones, rather than LT-HSCs, drive the bulk of adult hematopoiesis. However, the precise origin of these progenitors remains unclear. Our preliminary work using the transposon tagging technique developed in our lab to tag cells throughout embryonic development indicates that a large portion of adult blood bears tags associated with MPPs, without a corresponding tag in the HSC population. Thus, these MPPs are not clonally related to HSCs, but rather were tagged as a previously unappreciated population of embryonic MPPs (eMPPs). Mature blood contributions from eMPPs were detected when tagging was induced as early as E9.5. However, it remains unclear at which stage of development eMPPs first emerge, and whether earlier hematopoietic cells, such as hemogenic endothelium, are primed to generate eMPPs. By E11.5, increased expression of several lymphoid- associated transcripts appears to separate eMPPs from HSCs. We hypothesize that unique transcriptomic and epigenetic features can predict eMPP divergence during development. To test this hypothesis, we will perform single-cell ATAC-seq and RNA-seq on hematopoietic cells from embryos at several developmental stages. We anticipate that tracking transcriptomic and epigenetic state in embryonic hematopoietic populations will allow us to identify the emergence of eMPPs and, potentially, populations which are primed to generate them. Preliminary data also indicate that eMPPs’ large contributions to hematopoiesis decline with age, and that eMPPs generate the majority of mature lymphoid cells throughout all adult life. We hypothesize that eMPPs are vital to lymphoid production, and their age-dependent decline underlies myeloid bias in aged hematopoiesis. To test this hypothesis, we will genetically ablate eMPPs during fetal development and detect the effects of the loss of eMPPs on the lineage balance of mature blood and expansion of HSCs in the bone marrow. Conversely, we will attempt to rescue the aged phenotype via overexpression of Hoxb4 and Meis1, two genes associated with self- renewal in HSCs, in MPPs. Our findings will not only elucidate the origin eMPPs in development, but also have the potential to challenge our current understanding of aging in the hematopoietic system, providing insight into the etiologies of many age-related hematologic defects.

项目摘要/摘要 在人类中，衰老与慢性炎症和适应性免疫学的下降有关，导致 较高的感染率和心血管疾病率较高，成年人中有两个主要的死亡原因超过65。 血液学缺陷部分归因于老化造血的缺陷，这是偏见的髓样 血统。许多关于老年造血的研究依赖于移植测定或隔离特定的研究 造血干细胞（HSC）种群用于分子分析。这些研究强调了重要 老化HSC的特征，它们的方法集中于长期（LT）HSC，一小部分造血细胞， 通常不排除其他祖先种群。最近的研究员工诱导的遗传标签跟踪 不受干扰的本地造血。这些研究中的许多研究表明，大量祖细胞克隆， 而不是LT-HSC，而是驱动大部分成人造血。但是，这些祖细胞的确切起源 仍然不清楚。我们使用在实验室中开发的转座标记技术来标记细胞的初步工作 整个胚胎发育表明，大部分成年血熊与MPP相关的标签， 在HSC人群中没有相应的标签。那就是这些MPP与HSC无关，而是 而是被标记为先前未欣赏的胚胎MPP（EMPPS）人群。成熟的血液 在诱导标签时，检测到EMPP的贡献早在E9.5。但是，它仍然是 不清楚在哪个发展阶段首次出现EMPP，以及早期的造血细胞（例如 血液原始的植物，用于产生EMPP。到E11.5，几个淋巴样的表达增加 相关的成绩单似乎将EMPP与HSC分开。我们假设了独特的转录组和 表观遗传特征可以预测发育过程中的EMPP差异。为了检验这一假设，我们将执行 在几个发育阶段，来自胚胎的造血细胞上的单细胞ATAC-SEQ和RNA-SEQ。我们 预计在胚胎造血种群中跟踪转录组和表观遗传状态将使我们 确定EMPP的出现以及可能产生的人群的出现。初步的 数据还表明，EMPPS对造血的巨大贡献随着年龄的增长而下降，并且EMPP会产生 大多数成年成人的成熟淋巴样细胞。我们假设EMPP对淋巴而言至关重要 生产及其年龄依赖性下降是老化造血的髓样偏置的基础。测试这个 假设，我们将在胎儿发育过程中逐渐消灭EMPPS，并检测到丧失的影响 EMPP在骨髓中成熟血液和HSC膨胀的谱系平衡上。相反，我们会的 尝试通过Hoxb4和Meis1的过表达来挽救老化的表型，这是两个与自我相关的基因 在HSC中续订，MPPS。我们的发现不仅会阐明正在开发中的原始eMpps，而且还将 挑战我们当前对造血系统衰老的理解的潜力，提供有关 许多与年龄相关的血液学缺陷的病因。