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，以及干细胞衰竭 近年来，我们小组和其他人的工作引起了人们对这一问题的关注。 在群体水平上，肌肉干细胞（MuSC）的弹性随着年龄的增长而下降的机制 作为一个例子，我们已经证明了一条涉及 Notch 激活和 p53 活性增加可防止 MuSC 经历某种形式的细胞死亡、有丝分裂灾难，因为它们 该Notch/p53轴从静止状态被激活并进入细胞周期，并随着年龄的增长而减弱，并导致细胞周期的改变。 衰老的 MuSC 发生有丝分裂灾难的可能性增加，导致 MuSC 随着时间的推移而减少。 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 ATR 对这种压力的反应可以阻止细胞周期进入并保留我们拥有的 MuSC 群体。 还发现饮食干预，特别是禁食和生酮饮食，可能会增强 MuSC 的恢复能力 这些观察结果共同强调了 HDAC 活性和 p53 乙酰化介导的稳健过程。 保持 MuSC 的弹性并防止干细胞耗竭，这是衰老过程中出错的过程。 该提案的主要目标是更详细地探索这些过程，以确定分子 每个调解者，使用公正的屏幕来识别尚未未知的调解者，并追求复兴 恢复老化 MuSC 弹性的干预措施。 为了解决这些问题，该提案分为三个具体目标 1：检查变化。 Notch/p53 轴是与年龄相关的 MuSC 弹性降低的原因，我们将使用新的遗传模型。 调节 MuSC 中的 Notch 信号传导并测试免受有丝分裂影响的细胞的弹性特征 我们还将使用单细胞评估弹性细胞，以寻找 p53 下游介质的证据。 RNA-seq 目标 2：检查年轻和年老 MuSC 的复制应激和 ATR 反应。 ATR 的潜在下游介质 CDK12，在磷酸化蛋白质组学筛选中鉴定出，在保存 我们还将测试这种复制压力反应途径是否随着年龄的增长而变化。 目标 3：当 MuSC 从静止状态激活时，保护它们免受有丝分裂灾难。 阐明酮症促进 MuSC 恢复力的机制 我们将测试恢复力的增强。 使用三种不同的酮症诱导干预措施，我们将根据良好的情况测试作用机制 记录了主要循环酮体 β-羟基丁酸 (βHB) 作为组蛋白抑制剂的作用 我们还将测试酮症是否至少部分地增强 MuSC 的恢复能力。 促进 p53 活性和预防有丝分裂灾难，这些研究将共同​​推进我们的研究。 了解干细胞弹性机制以及如何增强衰老干细胞的弹性 促进整个生命周期的组织稳态和修复。