Proteostasis and stem cell aging

蛋白质稳态和干细胞衰老

• 批准号: 9127068
• 负责人: WILLIAM H MATSUI
• 金额: $ 20.26万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9127068
• 关键词: Activities of Daily Living; Acute; Address; Age; Aging; Aging-Related Process; Amino Acids; Biological Assay; Biological Models; Blood; Bone Marrow; Caloric Restriction; Cell Aging; Cell physiology; Chronic; Clinical; Data; Degenerative Disorder; Development; Elderly; Epigenetic Process; Equilibrium; FRAP1 gene; Functional disorder; Goals; Health; Hematopoiesis; Hematopoietic System; Hematopoietic stem cells; Homeostasis; Human; Immunity; In Vitro; Individual; Lead; Longevity; Mammals; Mediating; Morbidity - disease rate; Mus; Organ; Organism; Play; Polyribosomes; Process; Property; Protein Biosynthesis; Proteins; Proteome; Role; Sampling; Sirolimus; Specimen; Stem cells; TAL1 gene; Tissues; Translations; age related; aged; base; body system; cell age; cell type; clinically relevant; differential expression; effective therapy; functional restoration; improved; improved functioning; in vivo; mitochondrial dysfunction; mortality; novel; novel strategies; novel therapeutics; polypeptide; progenitor; protein aggregate; protein degradation; protein folding; protein misfolding; rate of change; regenerative therapy; repaired; restoration; self-renewal; stem; telomere; tissue regeneration; translation factor; treatment strategy

 DESCRIPTION (provided by applicant): During aging, the loss of stem cell function is thought to play a major role in organ degeneration and dysfunction. Therefore, strategies capable of restoring stem cells may lead to novel and effective therapies for a wide-range of degenerative disorders. Several cellular processes have been found to drive the aging process, but the precise mechanisms responsible for changes in stem cells are relatively unknown. The disruption of protein homeostasis (i.e., proteostasis) results in the intracellular accumulation of damaged and misfolded proteins and is a major determinant of aging. The majority of studies examining proteostasis have focused on protein folding and degradation in attempts to improve the elimination of toxic protein aggregates, but the rate of protein synthesis plays a major role i maintaining the integrity of the proteome as accelerated translation rates can lead to higher rates of incorrect amino acid incorporation as well as the misfolding of nascent polypeptides. Both caloric restriction and inhibition of the mammalian Target of Rapamycin (mTOR) can decrease protein synthesis rates and it is possible that improved proteostasis plays a major role in their capacity to extend lifespan across a range of organisms. We hypothesize that both quantitative and qualitative changes in protein synthesis are responsible for the age-related loss of stem cell function. We also hypothesize that reducing protein synthesis rates will restore proteostasis and the function of stem cells from elderly individuals. In order to address these hypotheses, we will study hematopoietic stem cells (HSCs) and progenitors since age-related changes in hematopoiesis have been well described. Furthermore, we will take advantage of our unique access to human bone marrow samples from normal donors ranging in age from 18- 75 years old that will allow us to maximize the human relevance of our studies in contrast to most studies that have investigated aging within murine hematopoiesis. Accordingly, we will: (1). determine the impact of aging on HSC and progenitor protein synthesis rates and the expression of translational machinery components and (2). determine the reversibility of age-related changes in HSPC function. For studies in Aim 1 we will quantify the rates of protein synthesis and turnover and correlate these results with in vitro and in vivo functional studies. Moreover, we will carry out polysome profiling to quantify changes in the expression of components of the translational machinery that occur with aging. In Aim 2, we will determine the impact of rapamycin and the role of differentially expressed regulators of translational on HSCs and progenitors from young and elderly donors. If successful, our findings will improve our understanding of the aging human hematopoietic system, define the role of proteostasis in aging stem cells, validate the results of murine studies regarding the effects of mTOR inhibition on HSCs, provide the basis for novel strategies to improve the function of both HSCs and other tissue-specific stem cells, and serve as the basis for the development of novel strategies to restore stem cell function in the elderly.

 描述（由申请人提供）：在衰老过程中，干细胞功能的丧失被认为在器官退化和功能障碍中发挥着重要作用，因此，能够恢复干细胞的策略可能会为多种疾病带来新的有效疗法。已发现多种细胞过程可驱动衰老过程，但导致干细胞变化的确切机制相对未知。蛋白质稳态（即蛋白质稳态）的破坏导致细胞内积累。 受损和错误折叠的蛋白质是衰老的主要决定因素，大多数研究蛋白质稳态的研究都集中在蛋白质折叠和降解上，试图改善有毒蛋白质聚集体的消除，但蛋白质合成速率在维持完整性方面起着重要作用。蛋白质组的加速翻译速度会导致更高的错误氨基酸掺入率以及新生多肽的错误折叠，热量限制和哺乳动物雷帕霉素靶点 (mTOR) 的抑制都会降低。蛋白质合成率的提高可能在延长一系列生物体的寿命方面发挥着重要作用，我们探索了蛋白质合成的量和质的变化是与年龄相关的干细胞功能丧失的原因。我们还认为，降低蛋白质合成率将恢复老年人干细胞的蛋白质稳态和功能。为了解决这些假设，我们将研究造血干细胞（HSC）和祖细胞与年龄相关的变化。此外，我们将利用我们独特的方法获取来自 18-75 岁正常捐赠者的人类骨髓样本，这将使我们的研究与大多数研究相比能够最大限度地发挥人类的相关性。因此，我们将：（1）确定衰老对 HSC 和祖蛋白合成率以及翻译机制成分表达的影响；（2）确定衰老的可逆性。对于目标 1 的研究，我们将量化蛋白质合成和周转率，并将这些结果与体外和体内功能研究相关联，此外，我们将进行多核糖体分析以量化表达的变化。在目标 2 中，我们将确定雷帕霉素的影响以及差异表达的翻译调节因子对年轻和老年供体的 HSC 和祖细胞的作用。提高我们对衰老人类造血系统的理解，定义蛋白质稳态在衰老干细胞中的作用，验证关于 mTOR 抑制对 HSC 影响的小鼠研究结果，为改善 HSC 和其他细胞功能的新策略提供基础组织特异性干细胞，并作为开发恢复老年人干细胞功能的新策略的基础。