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.

总结 干细胞衰竭是衰老的主要标志之一。在整个身体的组织中， 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， 再生能力已经证明，将年轻的功能恢复到老年干细胞可以改善 衰老组织的结构和功能。因此，了解干细胞衰老的驱动因素， 揭示组织再生甚至生物衰老目标的潜力。 尽管关于干细胞表型随年龄变化的信息非常丰富，但我们所知甚少 关于驱动这些变化的潜在分子机制。在这些潜在的 分子机制，我们已经探索了基因组不稳定性（另一个老化的标志）作为一个特征 衰老的干细胞在该提案中，我们提出基因组的不稳定性和DNA的积累 损伤是干细胞数量与年龄相关的下降的基础。使用肌肉干细胞（MuSC）作为 模型系统中，我们已经报道了衰老MuSC中DNA损伤增加的证据。这 DNA损伤的积累导致MuSC经历一种细胞损伤形式的倾向增加。 当它们试图进入细胞周期时，死亡被称为有丝分裂灾难， 修复肌肉我们发现，这种细胞死亡风险的增加与年龄相关的 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。与此同时，我们发现，ATR，一个关键的调解人， DNA损伤反应（DDR）的，是在静止的MuSC高度活跃。的首要目标 这项建议的研究是为了探索衰老的两个标志之间的机械关系- 基因组不稳定性和干细胞耗竭。 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 p53在衰老过程中对MuSC数量的调节作用。我们将使用功能获得和功能丧失 基因模型来验证这一假设。在目标2中，我们将研究ATR在MuSC维护中的作用 随年龄这些研究将包括一个公正的磷酸蛋白质组学筛选，以确定下游 在MuSC维持中的ATR介质。目标3将集中在p53靶基因NDRG 1上， 已经显示在低增殖状态的条件下调节癌细胞中的基因组完整性。在 初步研究，我们发现NDRG 1减缓了MuSC的激活，这对于 在细胞分裂之前修复DNA损伤。我们将研究NDRG 1在MuSC激活中的作用。 在老化期间，再次使用功能获得和功能丧失方法。这些研究将 推进我们对干细胞衰老的理解，并强调恢复年轻功能的方法， 老年干细胞作为一种方式，以提高组织的稳态和修复在老年人。