Identifying Drugs to Treat Age-Dependent Neurodegeneration

描述(由申请人提供)：确定导致细胞衰老和神经退化的分子机制已被证明是困难的。许多类型的损伤被认为是导致衰老和神经退化的原因，包括线粒体和核DNA突变、蛋白质错误折叠、聚集体形成、活性氧物种(ROS)和干细胞衰老。然而，关于哪种机制在衰老中起因果作用还没有形成共识。事实上，每个组织可能都有一套精选的过程，或者说是进一步加剧细胞衰退的“阿喀琉斯之踵”。在神经系统中，人们一致认为线粒体衰老、ROS依赖性损伤的积累以及含有泛素的蛋白质聚集体或包涵体的形成与大多数人类神经系统疾病有关，如阿尔茨海默氏症和帕金森氏病。越来越多的人认识到，自噬途径通过促进细胞损伤和蛋白质聚集体的去除来维持成熟的神经系统。该途径是高度保守的，我们发现自噬基因的表达谱显示在衰老的果蝇中枢神经系统中显着减少。与此同时，细胞损伤的标志和聚集体，如不溶性泛素化聚集体(IUP)，显示出戏剧性的增加。遗传分析还表明，关键基因的突变大大缩短了成年人的寿命(35%至60%)，并导致进行性神经缺陷，这些缺陷与阿尔茨海默氏症和其他神经退行性疾病有惊人的相似之处。更重要的是，我们观察到，在老化的神经系统中增强自噬可以抑制细胞损伤(IUP)的积累，并显著延长成年寿命。这项工作表明，可以用果蝇作为模型系统来检查促进神经元健康老化的因素。在这项建议中，我们利用自噬的保守调节来鉴定神经保护化合物，这些化合物可以增强自噬途径，促进寿命和神经功能。该项目涉及我们最初的第一阶段应用中提出的几种经过验证和优化的分析方法，旨在识别能够增强自噬、抑制聚集体形成和延长寿命的化合物。在特定的目标1中，还包括了一项评估不同治疗方法抑制氧化应激能力的另外一项测试。具体目标2代表了我们药物测试平台的扩展，通过检查不同化合物对几种表现出年龄相关性下降的成人行为的影响，来评估不同化合物促进神经元健康和功能的有效性。特定目的3利用自噬和其他关键保护途径的保守调节来识别那些改变老化神经系统中基因表达谱的神经保护化合物。这项提议的目标是更好地了解清除途径在衰老中的作用，并开发体内试验，以确定可用于治疗人类神经疾病的药物。

DESCRIPTION (provided by applicant): Defining the molecular mechanism that leads to cellular aging and neural degeneration has proven to be difficult. Many types of damage are thought to contribute to senescence and neural degeneration and include mitochondrial and nuclear DNA mutations, protein misfolding, aggregate formation, reactive oxygen species (ROS), and stem cell senescence. However, a consensus has not yet developed as to which mechanism plays a causal role in aging. Indeed, each tissue may have a select set of processes, or "Achilles' heel" that further exacerbated cellular decline. In the nervous system there is an agreement that mitochondrial senescence, the accumulation of ROS-dependent damage and the formation of protein aggregates or inclusion containing ubiquitin are involved with the most human neurological disorders, such as Alzheimer's and Parkinson's disease. There is a growing understanding that the autophagy pathway is involved with maintaining the mature nervous system by facilitating the removal of cellular damage and protein aggregates. The pathway is highly conserved and we found that expression profiles of autophagy genes show a significant decrease in the aging Drosophila CNS. At the same time, markers of cellular damage and aggregates, such as insoluble ubiquitinated aggregates (IUP), show a dramatic increase. Genetic analysis also shows that mutations in key genes significantly shorten adult lifespans (35 to 60%) and cause progressive neural defects that share striking similarities to those seen with Alzheimer's and other neurodegenerative disorders. Of greater significance is our observation that enhancing autophagy in the aging nervous system suppresses the accumulation of cellular damage (IUP) and significantly extends adult life spans. This work shows that examining factors that promote healthy neuronal aging can be done using Drosophila as a model system. In this proposal we take advantage of the conserved regulation of autophagy to identify neural protective compounds that enhance the pathway, promote longevity and neural function. This project involves several validated and optimized assays proposed in our original Phase-I application that were designed to identify compounds that enhanced autophagy, suppressed aggregate formation and extend life spans. In Specific Aim 1 an additional assay, which assesses the ability of different treatments to suppress oxidative stress was included. Specific Aim 2 represents an expansion of our drug-testing platform to assess the effectiveness of different compounds to promote neuronal health and function by examining their effect on several adult behaviors that show an age-dependent decline. Specific Aim 3 takes advantage of the conserved regulation of autophgy and other key protective pathways to identify those neural protective compounds that alter gene expression profiles in the aging nervous system. The goal of this proposal is to better understand the role of clearance pathways on aging and to develop in vivo assays that identify drugs that could be used for the treatment of human neurological disorders.