Aging and Stem Cell Resilience

衰老和干细胞恢复能力

• 批准号: 10544774
• 负责人: THOMAS A. RANDO
• 金额: $ 54.06万
• 依托单位: PALO ALTO VETERANS INSTIT FOR RESEARCH
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10544774
• 关键词: Acetylation; Address; Adult; Age; Aging; Attention; Blood; Caloric Restriction; Cell Aging; Cell Cycle; Cell Death; Cell Survival; Cells; Cytoprotection; Data; Diet; Dietary Intervention; Exhibits; Fasting; Functional disorder; Genetic Models; Goals; Heterogeneity; Histone Deacetylase; Histone Deacetylase Inhibitor; Homeostasis; Impairment; In Vitro; Individual; Injury; Intermittent fasting; Intervention; Ketone Bodies; Ketoses; Ketosis; Knock-out; Laboratories; Longevity; Mediating; Mediator; Mitotic; Molecular; Molecular Profiling; Muscle; Muscle satellite cell; Outcome; Pathway interactions; Phenotype; Population; Predisposition; Process; Publishing; Regenerative capacity; Rejuvenation; Resistance; Role; Signal Pathway; Signal Transduction; Stress; Structure; TP53 gene; Testing; Time; Tissues; Transgenic Organisms; Work; age related; aged; beta-Hydroxybutyrate; biological adaptation to stress; cellular resilience; decrease resilience; exhaustion; functional decline; in vivo; ketogenic diet; muscle aging; muscle regeneration; muscular structure; new therapeutic target; notch protein; novel; phosphoproteomics; preservation; prevent; promote resilience; regeneration potential; regenerative; repaired; replication stress; resilience; response; response to injury; satellite cell; screening; self-renewal; single-cell RNA sequencing; stem cell population; stem cells

Stem cells are responsible for homeostasis and repair of many tissues in the body, and stem cell exhaustion is one of the hallmarks of aging. In recent years, work from our group and others has drawn attention to the mechanisms by which the resilience of muscle stem cells (MuSCs) declines with age at the population level and at the single cell level. As one example, we have shown that a signaling pathway involving Notch activation and increased p53 activity prevents MuSCs from undergoing a form of cell death, mitotic catastrophe, as they activated out of quiescence and enter the cell cycle. This Notch/p53 axis declines with age and leads to an increased propensity of aged MuSCs to undergo mitotic catastrophe, leading to a decline in MuSCs over time. Furthermore, in preliminary studies, we have found that quiescent MuSCs exhibit evidence of replicative stress and that an ATR response to that stress prevents cell cycle entry and preserves the MuSC population. We have also found that dietary interventions, in particular fasting and a ketogenic diet, enhance MuSC resilience, perhaps mediated by HDAC activity and p53 acetylation. Together, these observations highlight robust processes to maintain MuSC resilience and prevent stem cell depletion, processes that go awry during the aging process. The primary goals of this proposal are to explore these processes in more detail, to identify the molecular mediators of each, to use unbiased screens to identify as yet unknown mediators, and to pursue rejuvenating interventions that restore resiliency to aged MuSCs. To address these issues, this proposal is divided into three Specific Aims. Aim 1: To examine changes of the Notch/p53 axis as a cause of the age-related reduction of MuSC resilience. We will use novel genetic models to modulate Notch signaling in MuSCs and test for resilience signatures of cells protected against mitotic catastrophe. We will also assess resilient cells for evidence of mediators downstream of p53 using single cell RNA-seq. Aim 2: To examine replicative stress and the ATR response in young and old MuSCs. We will examine a potential downstream mediator of ATR, CDK12, identified in a phosphoproteomic screen, in preserving resilience of the population. We will also test whether this replicate stress response pathway changes with age and protect MuSCs from undergoing mitotic catastrophe when they activate out of quiescence. Aim 3: To elucidate the mechanisms by which ketosis promotes MuSC resilience. We will test for enhancement of resilience using three different ketosis-inducing interventions, and we will test for mechanisms of action based on the well- documented role of the major circulating ketone body, beta-hydroxybutyrate (βHB), as an inhibitor of histone deacetylases (HDACs). We will also test whether ketosis enhances MuSC resilience, at least in part, by promoting p53 activity and preventing mitotic catastrophe. Together, these studies will advance our understanding of the mechanisms of stem cell resiliency and how to enhance the resilience of aged stem cells to promote tissue homeostasis and repair across the lifespan.

干细胞负责体内许多组织的稳态和修复，以及干细胞耗竭 是衰老的标志之一近年来，我们小组和其他人的工作引起了人们对 肌肉干细胞（MuSC）的弹性在群体水平上随年龄下降的机制， 在单细胞水平上。作为一个例子，我们已经表明，涉及Notch激活和 增加的p53活性防止MuSC经历一种形式的细胞死亡，有丝分裂灾难，因为它们 从静止状态激活并进入细胞周期。这个Notch/p53轴随着年龄的增长而下降， 老化的MuSC经历有丝分裂灾难的倾向增加，导致MuSC随时间下降。 此外，在初步研究中，我们发现静止的MuSC表现出复制应激的证据 并且对该应激的ATR反应阻止细胞周期进入并保存MuSC群体。我们有 还发现饮食干预，特别是禁食和生酮饮食，可能会增强MuSC的恢复力 由HDAC活性和p53乙酰化介导。总之，这些观察结果强调了稳健的流程， 保持MuSC的弹性，防止干细胞耗竭，这是衰老过程中出错的过程。 这项提案的主要目标是更详细地探索这些过程，以确定分子 调解人的每一个，使用公正的屏幕，以确定尚未未知的调解人，并追求振兴 干预措施，恢复老年MuSC的弹性。 为了解决这些问题，本提案分为三个具体目标。目标1：审查 Notch/p53轴作为年龄相关的MuSC弹性降低的原因。我们将使用新的基因模型 调节MuSC中的Notch信号传导，并测试保护细胞免受有丝分裂的弹性特征， 灾变我们还将评估弹性细胞的证据介质下游的p53使用单细胞 RNA测序目的2：研究年轻和老年MuSC中的复制应激和ATR反应。我们将研究 在磷酸化蛋白质组学筛选中鉴定的ATR的潜在下游介质CDK 12， 人口的弹性。我们还将测试这种重复的压力反应途径是否会随着年龄的增长而改变 并保护MuSCs在它们从静止状态激活时免于发生有丝分裂灾难。目标3： 阐明酮症促进MuSC恢复力的机制。我们将测试恢复能力的增强 使用三种不同的酮症诱导干预措施，我们将测试基于良好的作用机制， 主要循环酮体β-羟基丁酸（βHB）作为组蛋白抑制剂的作用已得到证实 脱乙酰酶（HDAC）。我们还将通过以下方式测试酮病是否至少部分增强MuSC的弹性 促进p53活性和防止有丝分裂灾难。总之，这些研究将推动我们的 了解干细胞弹性的机制以及如何增强衰老干细胞的弹性 以促进组织的稳态和整个生命周期的修复。