Replication Stress and Ribosome Biogenesis in Hematopoietic Stem Cell Aging

造血干细胞衰老中的复制应激和核糖体生物合成

• 批准号: 10684178
• 负责人: Carl Mitchell
• 金额: $ 4.77万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10684178
• 关键词: Age; Aging; Anemia; Automobile Driving; Biogenesis; Biological Markers; Biology; Blood; Bromodeoxyuridine; COVID-19; Cardiovascular Diseases; Cell Communication; Cell Cycle; Cell Cycle Regulation; Cell Separation; Cells; ChIP-seq; Characteristics; Chronic; Clinical; DNA Damage; DNA Maintenance; Data; Deceleration; Defect; Development; Disease; Down-Regulation; Elderly; Epigenetic Process; Erythroid; Exhibits; Failure; Fluorouracil; Functional disorder; Genes; Genetic Transcription; Genomic Instability; Goals; Health; Helicase Gene; Hematology; Hematopoiesis; Hematopoietic; Hematopoietic System; Hematopoietic stem cells; Homeostasis; Human; Immune; Impairment; In Vitro; Infection; Investigation; Knowledge; Label; Laboratories; Link; Longevity; Lymphoid; Lymphopoiesis; Maintenance; Malignant Neoplasms; Mammals; Measures; Metabolic; Modeling; Molecular; Molecular Analysis; Molecular Target; Morbidity - disease rate; Mus; Mutation; Myeloid Cells; Natural regeneration; Organism; Output; Pathogenicity; Pathway interactions; Phenotype; Physiologic pulse; Play; Population; Predisposition; Process; Production; Proteins; Reporter; Ribosomal DNA; Ribosomal Proteins; Ribosomes; Signal Pathway; Signal Transduction; Stress; Symptoms; System; Therapeutic; Tissues; Translational Regulation; Translations; Up-Regulation; Vaccination; adaptive immunity; age related; base; biological adaptation to stress; cardiovascular health; cdc Genes; clinically relevant; cytopenia; empowerment; experimental study; frailty; functional decline; gene repression; genetic approach; hematopoietic hierarchy; hematopoietic stem cell aging; imaging approach; immune function; improved; in vivo; mortality; mouse genetics; novel; older driver; programs; proteostasis; regeneration potential; replication stress; stem cell biology; stem cell function; systemic inflammatory response; targeted treatment; therapy design; thrombocytosis; transcription factor; vaccine efficacy

PROJECT SUMMARY/ABSTRACT Diseases of the elderly are an increasingly urgent societal problem due to the worldwide increases in lifespan. The aging of the hematopoietic system is caused by dysfunction in hematopoietic stem cells (HSC) and is characterized by anemia, thrombocytosis, and overproduction of myeloid cells at the expense of lymphopoiesis. Together these defects play a key role in the development of cardiovascular diseases, loss of adaptive immunity that impedes vaccination, and establishment of chronic systemic inflammation that damages tissue and contributes to frailty. HSC aging is conserved in mammals, with human and murine old HSCs (oHSC) both exhibiting reduced regenerative potential, genomic instability, epigenetic drift, metabolic rewiring, and altered cell-cell communication. Although these overt phenotypic features are widely understood to be significant characteristics of oHSCs, we still know little about their underlying molecular mechanisms and functional consequences. This gap in knowledge has hindered efforts to delay or reverse HSC aging at its root. Our lab identified replication stress as a potent driver of oHSC dysfunction and impaired regenerative potential. This is especially severe at fragile ribosomal DNA loci, leading to loss of ribosome biogenesis. This project aims to determine the functional consequences of reduced ribosome biogenesis for oHSCs, and to identify the programs that underly replication stress initiation with a goal to target them to restore oHSC function. Our preliminary data suggest that oHSCs are defective in their capacity for protein translation, even though their mitogenic signaling pathways are overactive. They also suggest chronic activation of the Nucleolar Stress Response (NSR) as a consequence of replication stress in oHSCs. Furthermore, we have evidence for epigenetic alterations and cell cycle transcriptional repression consistent with Mcm downregulation and replication stress initiation. In Aim 1, we will determine the extent of defective protein translation in quiescent and activated oHSCs using in vitro and in vivo approaches. We will also interrogate the signaling pathways driving defective protein translation in oHSCs focusing in particular on NSR activation using a mouse genetic approach. These experiments will establish how defective proteostasis contribute to HSC aging, and the connection between replication and nucleolar stress in driving oHSC impaired regeneration potential. In Aim 2, we will identify the transcription factors or cell cycle regulators responsible for replication stress initiation, and also uncover the epigenetic basis for this defect. We will then assess whether pharmocological tuning of specific epigenetic modifiers can restore oHSC function. These experiments will dissect the molecular underpinnings of replication stress and determine whether correcting this cell-intrinsic hallmark of HSC aging will improve oHSC regenerative potential. Altogether, our proposed investigations are promising avenues to better understand and treat HSC aging. They have exciting implications for identifying actionable targets for promoting HSC functional longevity, a logical strategy towards restoring blood and immune function in the elderly.

项目总结/摘要 由于世界范围内老年人疾病的增加，老年人疾病已成为一个日益紧迫的社会问题 寿命造血系统的老化是由造血干细胞（HSC）功能障碍引起的， 其特征是贫血、血小板增多和骨髓细胞过度生成， 淋巴细胞生成这些缺陷共同在心血管疾病的发展中起关键作用， 适应性免疫，阻碍疫苗接种，并建立慢性全身性炎症，损害 组织，并有助于脆弱。HSC老化在哺乳动物中是保守的，人和鼠的老HSC（oHSC） 两者都表现出降低的再生潜力、基因组不稳定性、表观遗传漂移、代谢重新布线，以及 改变了细胞间的交流尽管这些明显的表型特征被广泛认为是重要的 尽管oHSC的特性，我们仍然对其潜在的分子机制和功能知之甚少， 后果这种知识上的差距阻碍了从根本上延缓或逆转HSC衰老的努力。我们实验室 将复制应激确定为oHSC功能障碍和再生潜力受损的有力驱动因素。这是 尤其是在脆弱的核糖体DNA位点，导致核糖体生物合成的丧失。该项目旨在 确定oHSC核糖体生物合成减少的功能后果，并确定程序 这是复制应激起始基础，目的是靶向它们以恢复oHSC功能。我们的初步 数据表明，oHSC在蛋白质翻译能力方面存在缺陷，即使它们的促有丝分裂能力 信号通路过度活跃它们还表明核仁应激反应（NSR）的慢性激活 作为oHSC中复制应激的结果。此外，我们有证据表明表观遗传改变， 细胞周期转录抑制与Mcm下调和复制应激启动一致。在Aim中 1，我们将使用体外细胞培养技术确定静止和活化的oHSC中缺陷蛋白翻译的程度。 和体内方法。我们还将询问驱动缺陷蛋白质翻译的信号通路， oHSC特别关注使用小鼠遗传方法的NSR激活。这些实验将 建立蛋白质稳态缺陷如何促进HSC老化，以及复制和 驱动oHSC的核仁应激损害了再生潜力。在目标2中，我们将识别转录 因子或细胞周期调节剂负责复制应激启动，也揭示了表观遗传基础 对于这个缺陷。然后，我们将评估特定表观遗传修饰剂的药理学调整是否可以恢复 oHSC功能。这些实验将剖析复制应激的分子基础， 是否纠正HSC老化的细胞内在标志将改善oHSC再生潜力。总的来说， 我们提出的研究是更好地理解和治疗HSC衰老的有希望的途径。他们有 确定促进HSC功能寿命的可操作目标的令人兴奋的意义，一种逻辑策略 恢复老年人的血液和免疫功能。