Genomic Instability as A Driver of Stem Cell Exhaustion

基因组不稳定性是干细胞衰竭的驱动因素

• 批准号: 10722284
• 负责人: THOMAS A. RANDO
• 金额: $ 43.38万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-15 至 2028-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10722284
• 关键词: ATR gene; Address; Age; Aging; Area; Biological Models; CRISPR screen; Cell Count; Cell Cycle; Cell Death; Cell Maintenance; Cell Survival; Cell division; Cell physiology; Cells; Cellular Structures; Cessation of life; Complement; DNA Damage; DNA Repair; Data; Defect; Functional disorder; Genes; Genetic Models; Genomic Instability; Goals; Health; Homeostasis; Human; Hyperactivity; Impairment; Individual; Intervention; Laboratories; Laboratory Research; Life; Link; Longevity; Maps; Mediator; Mitotic; Modification; Molecular; Mus; Muscle; Muscle satellite cell; Muscular Atrophy; Pathway interactions; Pharmacology Study; Phenotype; Predisposition; Prevention; Process; Proliferating; Proteins; Regenerative capacity; Regulation; Rejuvenation; Reporting; Research; Risk; Role; Structure; TP53 gene; Testing; Time; Tissues; Tumor Suppressor Proteins; age related; age-related muscle loss; aged; cancer cell; exhaust; exhaustion; gain of function; genetic approach; genome integrity; genome-wide; healthspan; improved; interest; loss of function; muscle aging; muscle regeneration; nutlin 3; phosphoproteomics; preservation; prevent; repaired; response; stem cell aging; stem cell function; stem cell population; stem cell survival; stem cells

SUMMARY Stem cell exhaustion is one of the key hallmarks of aging. In tissues throughout the body, there is a decline in stem cell number and function with age, leading to a loss of tissue homeostasis and regenerative capacity. Restoring youthful functionality to aged stem cells has been shown to improve the structure and function of aged tissues. As such, understanding the drivers of stem cell aging has the potential to reveal targets for rejuvenating tissue and even organismal aging. Despite the wealth of information on the phenotypic changes of stem cells with age, little is known about the underlying molecular mechanisms that drive those changes. Among those potential molecular mechanisms, we have explored genomic instability (another hallmark of aging) as a feature of aged stem cells. In the proposal, we propose that genomic instability and the accumulation of DNA damage underlie the age-related decline in stem cell number. Using muscle stem cells (MuSCs) as a model system, we have reported evidence of increases in DNA damage in aged MuSCs. This accumulation of DNA damage leads to an increased propensity of MuSCs to undergo a form of cell death called mitotic catastrophe when they attempt to enter the cell cycle when they are called upon to repair muscle. We found that this increased risk of cell death is associated with an age-related decrease in p53 activity, and that stabilizing or enhancing p53 reduces mitotic catastrophe and promotes muscle repair in aged mice. At the same time, we have found that that ATR, a key mediator of the DNA damage response (DDR), is highly active in quiescent MuSCs. The primary goal of the studies of this proposal are to explore the mechanistic relationship between two hallmarks of aging - genomic instability and stem cell exhaustion. Toward this goal, we will pursue three independent Specific Aims. In Aim 1, we will explore the role of p53 in the regulation of MuSC number during aging. We will use gain-of-function and loss-of-function genetic models to test this hypothesis. In Aim 2, we will examine the role of ATR in MuSC maintenance with age. These studies will include an unbiased phosphoproteomic screen to determine downstream mediators of ATR in MuSC maintenance. Aim 3 will focus on a p53 target gene, NDRG1, which has been shown to regulate genomic integrity in cancer cells under conditions of low proliferative states. In Preliminary Studies, we have found that NDRG1 slows MuSC activation, which is essential for the repair of DNA damage prior to cell division. We will examine the role of NDRG1 in MuSC activation during aging, again using gain-of-function and loss-of-function approaches. Together, these studies will advance our understanding of stem cell aging and highlight approaches to restore youthful function to aged stem cells as a way to enhance tissue homeostasis and repair in older individuals.

概括 干细胞耗竭是衰老的关键标志之一。在全身的组织中，有一个 随着年龄的增长，干细胞数量和功能下降，导致组织稳态丧失 再生能力。已证明使衰老干细胞恢复年轻功能可以改善 老化组织的结构和功能。因此，了解干细胞衰老的驱动因素已经 有可能揭示使组织恢复活力甚至机体衰老的目标。 尽管有大量关于干细胞随年龄的表型变化的信息，但人们知之甚少 关于驱动这些变化的潜在分子机制。在那些有潜力的人当中 分子机制，我们探索了基因组不稳定性（衰老的另一个标志）作为一个特征 老化的干细胞。在提案中，我们提出基因组不稳定性和 DNA 积累 损伤是与年龄相关的干细胞数量下降的基础。使用肌肉干细胞（MuSC）作为 模型系统中，我们报告了老化 MuSC 中 DNA 损伤增加的证据。这 DNA 损伤的积累导致 MuSC 发生某种细胞形式的可能性增加 当它们试图进入细胞周期时，被称为有丝分裂灾难的死亡 修复肌肉。我们发现细胞死亡风险的增加与年龄相关 p53 活性降低，稳定或增强 p53 可减少有丝分裂灾难， 促进老年小鼠的肌肉修复。同时，我们发现ATR，一个关键的中介 DNA 损伤反应 (DDR) 在静止的 MuSC 中高度活跃。该组织的首要目标是 该提案的研究旨在探索衰老的两个标志之间的机制关系 - 基因组不稳定和干细胞耗竭。 为了实现这一目标，我们将追求三个独立的具体目标。在目标 1 中，我们将探讨角色 p53 在衰老过程中 MuSC 数量调节中的作用。我们将使用功能获得和功能丧失 遗传模型来检验这一假设。在目标 2 中，我们将研究 ATR 在 MuSC 维护中的作用 随着年龄的增长。这些研究将包括公正的磷酸化蛋白质组筛选，以确定下游 MuSC 维护中 ATR 的介导者。目标 3 将重点关注 p53 靶基因 NDRG1，该基因具有 已被证明可以在低增殖状态下调节癌细胞的基因组完整性。在 初步研究，我们发现 NDRG1 可以减缓 MuSC 的激活，这对于 修复细胞分裂前的 DNA 损伤。我们将研究 NDRG1 在 MuSC 激活中的作用 在衰老过程中，再次使用功能获得和功能丧失的方法。这些研究共同将 增进我们对干细胞衰老的理解，并强调恢复年轻功能的方法 衰老干细胞作为增强老年人组织稳态和修复的一种方式。