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.

项目总结/摘要 在人类中，衰老与慢性炎症和适应性免疫力下降有关，导致 感染和心血管疾病的发病率较高，这是65岁以上成年人死亡的两个主要原因。这些 血液学缺陷部分是由于老年造血缺陷，其偏向于骨髓 血统许多关于老年造血的研究依赖于移植试验或分离特异性造血干细胞。 造血干细胞（HSC）群体用于分子分析。虽然这些研究强调了重要的 由于衰老HSC的特征，他们的方法集中于长期（LT）HSC，一小部分造血细胞， 往往排斥其他祖先群体。最近的研究采用诱导基因标签来跟踪 天然造血系统许多研究表明，大量的祖细胞克隆， 而不是LT-HSC，驱动大部分成人造血。然而，这些祖先的确切起源 仍不清楚我们的初步工作是使用我们实验室开发的转座子标记技术来标记细胞 在整个胚胎发育过程中表明大部分成人血液带有与MPP相关的标记， 而在HSC群体中没有相应的标签。因此，这些MPP与HSC不存在克隆相关性，但 而是被标记为以前未被重视的胚胎MPPs（eMPPs）群体。成熟血 当早在E9.5诱导标记时，检测到来自eMPP的贡献。但委员会仍 不清楚eMPPs在哪个发育阶段首次出现，以及早期造血细胞，如 生血内皮被引发以产生eMPP。到E11.5，几种淋巴样- 相关的转录物似乎将eMPP与HSC分开。我们假设独特的转录组学和 表观遗传特征可以预测发育过程中的eMPP分化。为了验证这一假设，我们将 单细胞ATAC-seq和RNA-seq对来自几个发育阶段的胚胎的造血细胞的作用。我们 我预计，跟踪胚胎造血群体的转录组和表观遗传状态将使我们能够 以确定eMPPs的出现，并可能确定准备产生它们的人群。初步 数据还表明，eMPPs对造血的巨大贡献随着年龄的增长而下降， 大多数成熟的淋巴细胞贯穿整个成年期。我们假设eMPPs对淋巴细胞的增殖和分化至关重要。 它们的年龄依赖性下降是老年造血中髓样偏向的基础。为了验证这一 假设，我们将在胎儿发育过程中基因消融eMPPs，并检测eMPPs丢失的影响。 eMPP对成熟血液的谱系平衡和骨髓中HSC的扩增的影响。相反，我们将 试图通过Hoxb 4和Meis 1的过表达来拯救老年表型，这两个基因与自身免疫相关， 造血干细胞和MPP的更新。我们的研究结果不仅将阐明eMPPs在发育过程中的起源， 有可能挑战我们目前对造血系统衰老的理解， 许多与年龄相关的血液缺陷的病因。