Dissecting the integrated mechanisms of protein turnover to prevent proteostatic decline with aging

剖析蛋白质周转的综合机制，以防止蛋白质沉积随衰老而下降

• 批准号: 10706458
• 负责人: Benjamin Francis Miller
• 金额: $ 70万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-30 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10706458
• 关键词: Adult; Age; Aging; Astrocytes; Brain; Cell Nucleus; Cell Proliferation; Cells; Confusion; Consensus; DNA; Data; Deterioration; Deuterium Oxide; Disease; Elderly; Estradiol; Goals; Heterogeneity; Individual; Isotope Labeling; Isotopes; Label; Longevity; Maintenance; Mass Spectrum Analysis; Measurement; Methodology; Methods; Mus; Muscle Cells; Neurons; Pathway interactions; Predisposition; Protein Biosynthesis; Protein Dynamics; Proteins; Proteomics; Quality Control; Research; Sirolimus; Skeletal Muscle; Testing; Therapeutic; Time; Tissue Sample; Tissues; age related; aged; cell type; improved; in vivo; mTOR inhibition; mouse model; novel; novel strategies; postmitotic; prevent; protein degradation; proteostasis; satellite cell; stable isotope

SUMMARY Proteostatic mechanisms fail with advancing age, resulting in the accumulation of damaged and dysfunctional proteins. Protein breakdown and replacement with newly synthesized proteins (protein turnover) is the primary mechanism to mitigate accumulation of damaged proteins over time. There are several conflicting findings related to protein turnover, aging, and treatments that slow aging, which leave the field with fundamental contradictions regarding protein turnover as a proteostatic mechanism. The current project seeks to understand the fundamental mechanisms that regulate proteostatic maintenance so that we can overcome a barrier to targeting this pillar of aging to slow age-related decline. Our studies indicate that: 1) aging does not universally decrease protein turnover, and in fact it increases the turnover of many proteins, 2) aging deceases the number of proteins that turnover (for which we introduce the term dynamic pool size), 3) treatments that extend lifespan have nearly an equal number of proteins that increase and decrease protein synthesis, which contradicts the notion that treatments that extend lifespan slow protein synthesis, and 4) some treatments that increase lifespan decrease cell proliferation, which by itself decreases protein turnover in a non- determinant manner. To date, these studies have been limited to tissue samples, which has restricted the understanding of how individual cell types within a tissue influence overall tissue proteostasis. To overcome these unknowns, the proposed studies use mouse models that allow cell-specific isolation of proteins and nuclei in skeletal muscle and brain. The project will use both discovery-based and targeted proteomics with novel deuterium oxide (D2O) labeling to examine cell-type-specific individual protein turnover and cell replication. Through loss of proteostatic maintenance (aging) and gain of proteostatic maintenance (treatments that slow aging), we will address the following specific aims: to determine cell-type specific proteins susceptible to proteostatic decline with aging, to determine how a treatment that inhibits mTOR improves proteostasis, and to determine how a treatment that does not directly inhibit mTOR improves proteostasis. The hypotheses are that: the loss of proteostasis with aging results from cell-type specific changes in individual protein turnover rates and decreases in the dynamic protein pool size, that inhibiting mTOR improves proteostatic maintenance by decreasing cell proliferation while increasing turnover and dynamic pool size of proteins that are susceptible to proteostatic decline, and that a lifespan-extending treatment that does not directly inhibit mTOR improves proteostatic maintenance by mechanisms that do not include slowed cell proliferation. Progress toward targeting age-related proteostatic deterioration has been hindered by contradictory and paradoxical results from protein turnover studies. We expect that our approaches will narrow the scope of proteins susceptible to proteostatic decline, and more importantly, will make significant advancements toward strategies to target these proteins to maintain proteostasis with age.

概括 蛋白质抑制机制随着年龄的增长而失效，导致受损和功能失调的积累 蛋白质。蛋白质分解和新合成蛋白质的替代（蛋白质周转）是主要的 随着时间的推移，减轻受损蛋白质积累的机制。有几个相互矛盾的发现 与蛋白质周转、衰老和延缓衰老的治疗相关，这为该领域留下了基础 关于蛋白质周转作为蛋白质抑制机制的矛盾。当前的项目旨在 了解调节蛋白质维持的基本机制，以便我们能够 克服针对这一老龄化支柱以减缓与年龄相关的衰退的障碍。我们的研究表明： 1) 衰老并不会普遍降低蛋白质周转率，事实上，它会增加许多蛋白质的周转率， 2) 衰老会减少周转的蛋白质数量（为此我们引入术语“动态池大小”），3) 延长寿命的治疗方法中增加和减少蛋白质的蛋白质数量几乎相同 合成，这与延长寿命的治疗会减缓蛋白质合成的观点相矛盾，4）一些 延长寿命的治疗会减少细胞增殖，这本身就会降低非细胞中的蛋白质周转率。 决定性的方式。迄今为止，这些研究仅限于组织样本，这限制了 了解组织内的单个细胞类型如何影响整体组织蛋白质稳态。克服 这些未知数，拟议的研究使用小鼠模型，允许细胞特异性分离蛋白质和细胞核 在骨骼肌和大脑中。该项目将使用基于发现的蛋白质组学和具有新颖性的靶向蛋白质组学 氧化氘 (D2O) 标记可检查细胞类型特异性的个体蛋白质周转和细胞复制。 通过失去蛋白质维持（衰老）和获得蛋白质维持（减缓衰老的治疗） 衰老），我们将解决以下具体目标：确定易受衰老影响的细胞类型特异性蛋白质 蛋白质稳态随着衰老而下降，以确定抑制 mTOR 的治疗如何改善蛋白质稳态，并 确定不直接抑制 mTOR 的治疗如何改善蛋白质稳态。假设是： 随着年龄的增长，蛋白质稳态的丧失是由细胞类型特定的个体蛋白质周转率变化和 动态蛋白质库大小减少，抑制 mTOR 可通过以下方式改善蛋白质维持： 减少细胞增殖，同时增加易受影响的蛋白质的周转和动态池大小 蛋白质抑制下降，并且不直接抑制 mTOR 的延长寿命的治疗可以改善 通过不包括减慢细胞增殖的机制来维持蛋白质抑制。瞄准目标的进展 蛋白质的矛盾和矛盾的结果阻碍了与年龄相关的蛋白质抑制退化 营业额研究。我们期望我们的方法将缩小易受蛋白抑制影响的蛋白质的范围 更重要的是，将在针对这些蛋白质的策略方面取得重大进展 随着年龄的增长保持蛋白质稳态。