Molecular Mechanisms Regulating Age-Related Cognitive Decline

 描述(由申请人提供)：神经元的老化会导致功能障碍和认知能力下降，但神经元到底是如何衰老的还不清楚。特别是，导致这些变化的关键基因尚未确定，但如果发现，将是理想的治疗靶点。我们的假设是，特定神经元中随年龄变化的基因子集负责认知能力随年龄下降的变化。我们的工作是识别老年人和保持认知功能更长时间的长寿突变体的基因表达变化，这将使我们能够识别这些关键基因。如果这些调节器在进化上是保守的，如果它们在人类神经元中也随着年龄的增长而下降，那么它们可能是很好的干预目标。在我们之前的研究中，我们开发了一种方法来测量线虫的积极嗅觉学习、短期记忆和长期记忆。我们发现，这些过程的分子成分在蠕虫和哺乳动物之间是共享的，这表明线虫是一个很好的模型系统，可以更充分地了解记忆的分子和细胞需求。此外，我们评估了学习、短期记忆和长期记忆随年龄、长寿突变和阿尔茨海默病模型的变化。我们发现，转录因子CREB的水平限制了长期记忆，并随着年龄的增长而下降，这解释了记忆能力随年龄的下降。我们接着确定了CREB记忆所需的下游靶点，以及CREB活动的神经元位置，扩展了对CREB活动的了解，超出了其他系统中已知的知识。然而，其他行为是如何随着年龄而受到限制的还没有在分子水平上被理解，我们的目标是找出调节认知功能随年龄保持的关键因素。为了完善我们的分析，我们开发了一种从成虫中分离细胞的新方法，首次允许对老化蠕虫的单细胞类型进行转录分析。我们正在利用这项新技术来识别不同神经元类型中随年龄和长寿突变而变化的基因。除了获得单个细胞类型的基本转录组以确定它们的特性外，我们现在还可以评估它们随年龄的个体转录变化。我们还利用了具有扩展功能的长寿突变体，使我们能够识别随着年龄增长而维持功能的关键基因。这是唯一可用于线虫的关键工具。这些变化的效果可以通过运动性、趋化性、学习、记忆、再生和形态随年龄增长的测试来评估。拟议的实验将使用我们新开发的方法来确定神经元如何随着年龄的增长而失去执行特定功能的能力。此外，我们将把对这些关键基因的神经元特异性拯救与行为分析相结合，以确定它们的作用，并测试它们的活性是否足以防止特定的行为随年龄下降。这些信息将给我们前所未有的分辨率来识别神经元随年龄增长的致病变化。

 DESCRIPTION (provided by applicant): The aging of neurons causes dysfunction and cognitive decline, but exactly how neurons age is not yet understood. In particular, the key genes that are responsible for these changes have not been identified, but would be ideal therapeutic targets if found. Our hypothesis is that a subset of the genes that change with age in specific neurons is responsible for changes in declines in cognitive ability with age. Our work identifying gene expression changes in aging adults and in longevity mutants that maintain cognitive functions longer will allow us to identify these key genes. These regulators, if evolutionarily conserved, may be good targets for intervention if they also decline with age in human neurons. In our previous studies, we developed assays to measure C. elegans positive olfactory learning, short-term memory, and long-term memory. We found that the molecular components of these processes are shared between worms and mammals, demonstrating that C. elegans is a good model system to more fully understand the molecular and cellular requirements of memory. Further, we assessed the changes in learning, short-term memory, and long-term memory with age, in longevity mutants, and in models of Alzheimer's Disease. We found that levels of the transcription factor CREB limit long-term memory and fall with age, explaining the loss of memory ability with age. We went on to identify CREB's downstream targets required for memory, as well as the neuronal site of CREB activity, extending the knowledge of CREB's activity beyond what is known in other systems. However, how other behaviors are limited with age is not yet understood at the molecular level, and we aim to identify key factors that regulate the maintenance of cognitive function with age. In order to refine our analyses, we have developed a novel method to isolate cells from adult C. elegans, allowing transcriptional analysis of single cell types in aging worms for the first time. We are leveraging that new technique to identify genes that change with age and in longevity mutants in different neuron types. In addition to obtaining the basal transcriptome for individual cell types n order to characterize their identities, we can now assess their individual transcriptional changes with age. We have also utilized longevity mutants with extended functions, allowing us to identify key genes that maintain function with age. This is a key tool that is uniquely available i C. elegans. The effect of these changes can then be assessed through tests of motility, chemotaxis, learning, memory, regeneration, and morphology with age. The proposed experiments will use our newly developed methodology to determine how neurons lose the ability to carry out specific functions with age. Further, we will combine neuron-specific rescue o these key genes with behavioral assays to determine their roles and test whether their activity is sufficient to prevent specific behavioral declines with age. This information will give us unprecedented resolution in identifying causative changes in neurons with age.