The Role of the Proteasome in Aging

描述（由申请人提供）：由于其在细胞中蛋白质转换的已知作用，泛素-蛋白酶体途径有望成为细胞衰老的关键参与者。蛋白酶体是一种多功能、多亚基的蛋白水解酶，是该途径的焦点，负责控制短寿命代谢调节蛋白和受损长寿命蛋白的裂解。调节作用和“垃圾清除”功能都可能在与年龄相关的代谢减慢和疾病中起作用。然而，表明蛋白酶体与衰老有关的研究是有限的、不确定的，有时甚至是相互矛盾的。我建议以一种真正全面的方式来表征衰老小鼠肝组织中的蛋白酶体组装：分别在不同的亚细胞区室中，并考虑活性、特异性、组装状态和亚基组成。新出现的证据表明，蛋白酶体基于亚细胞定位执行特定职责，证明了我的方法是正确的。我假设存在一系列与年龄相关的变化，这些变化共同形成了一种特征模式，构成了衰老的特征。我希望把这种特征称为蛋白酶体老化指数。我的初步数据支持这种指数可以被揭示的观点。具体而言，我建议：(1)针对蛋白酶体的亚细胞定位，定义每个年龄组的蛋白酶体衰老指数。我将对蛋白酶体的以下特性进行分子分析：蛋白酶体亚组合的含量和组成，亚组合中选定亚单位的蛋白质含量以及所有三个活性位点的肽酶活性，这些都是用模型底物确定的。我将把蛋白酶体指数与天然底物的切割模式联系起来。(3)最后，我将利用蛋白酶体老化指数建立氧化应激小鼠模型中蛋白酶体通路的状态：以氧化应激增加为特征的SOD1-/-小鼠和接受热量限制的小鼠作为氧化应激降低的模型。蛋白酶体衰老指数的成功推出将为研究蛋白酶体及其分子环境中与年龄相关的变化、了解这些变化的生理后果以及提出纠正这些变化的方法提供一个新的平台。蛋白酶体是一种多功能酶，负责控制大多数细胞蛋白质的降解，与年龄相关的蛋白质周转下降有关。我计划定义一种与年龄相关的蛋白酶体变化模式：“衰老蛋白酶体指数”。这种指数将有助于检测细胞老化的迹象，并有助于建立旨在控制衰老过程的治疗方法。

DESCRIPTION (provided by applicant): Due to its known role in protein turnover in the cell, the ubiquitin-proteasome pathway is expected to be a key player in cellular aging. The proteasome, a multifunctional, multisubunit proteolytic enzyme, is a focal point in the pathway and is in charge of controlled cleavage of short-lived metabolic regulator proteins and damaged long-lived proteins. Both the regulatory role and the "garbage removal" function may have a role in age-related metabolic slowdown and diseases. However, studies implicating the proteasome in aging have been limited, inconclusive, and at times contradictory. I propose to characterize proteasomal assemblies in aging mice liver tissue in a truly comprehensive manner: separately in distinct subcellular compartments, and taking into account activity, specificity, assembly status, and subunit composition. The emerging evidence that proteasomes perform specific duties based on subcellular location justifies my approach. I hypothesize that there is a set of age-related alternations, which collectively form a characteristic pattern of properties that constitutes a signature of aging. I wish to call such signature the proteasome aging index. My preliminary data support the notion that such index can be revealed. Specifically, I propose to: (1) define the proteasome aging index in each age group specific for subcellular localization of proteasomes. I will perform molecular profiling of the following properties of proteasome: content and composition of proteasome subassemblies, protein content of selected subunits of the subassemblies and peptidase activities of all three active sites, determined with model substrates. (2) I will correlate the proteasome index with the pattern of cleavage of natural substrates. (3) Finally, I will employ the proteasome aging index to establish the state of the proteasome pathway in the oxidative stress mice models: the SOD1-/- mice characterized by an increased oxidative stress and mice subjected to caloric restriction accepted as a model of decreased oxidative stress. Successful launching of the proteasome aging index will serve as a novel platform to pursue age-related alterations in the proteasome and its molecular context, learning about physiological consequences of the changes, and propose the means to correct them. The proteasome, a multifunctional enzyme responsible for controlled degradation of most of cellular proteins, has been linked to an age-related decline in protein turnover. I plan to define a pattern of age-related changes in the proteasome: the "proteasome index of aging". Such an index will help to detect signs of cellular aging and help to establish treatments aiming at controlling the aging processes.