Long-Lived Synaptic Proteins

项目摘要 记忆可以持续一个有机体的一生。数十亿神经元之间的动态通信 突触是信息处理的基础，并使记忆的编码和存储成为可能。变化 通过突触可塑性的突触强度和结构被广泛推测为 记忆的形成和储存。研究已经确定了细胞信号事件和分子重排 这是突触可塑性启动的基础然而，关于分子水平的了解却少得多。 使突触强度和记忆持续时间延长的基础。当初始突触 可塑性和长期记忆编码需要蛋白质合成，经过一段时间的巩固，记忆 存储变得独立于蛋白质合成或神经活动，这表明记忆是存储在一个 非常稳定的分子实体然而，在此期间，大多数已知的单个蛋白质 弥补突触将周转，被降解，并在几个小时到几天内更换。因此 问题仍然是什么物理基础的持久性持久的记忆。一 特别长寿的蛋白质（LLP） 存在于突触中并作为分子锚 保持定义给定记忆的突触强度或网络属性。 虽然先前研究已 证明了LLP在中枢神经系统中的存在，特别是在非分裂核中 细胞，迄今为止还没有研究解决这些蛋白质是否存在于突触中，并有助于 建立和维持长期记忆。为了研究这个假设，我们设计了一个 无偏见的，基于蛋白质组学的方法来识别突触中的LLP并表征其神经元 功能将在体内和体外使用稳定同位素代谢脉冲追踪标记来测量 神经元和突触蛋白质组的半衰期。这些实验将进一步结合行为 和药理学操作来研究记忆形成和神经元活动如何影响蛋白质 周转鉴定的候选蛋白质将使用生物化学，细胞生物学， 电生理，成像和行为方法，以确定这些LLP如何有助于 突触/神经元功能和记忆。在细胞的代谢活性环境中，已知 蛋白质会受到氧化损伤。有限法律责任合伙的这种损害可能是脆弱性的来源， 在衰老过程中导致功能衰退。本提案中所描述的实验将显著 有助于我们理解LLP在大脑中的功能及其在记忆形成中的潜在作用， 长期储存和与年龄相关的认知能力下降。

PROJECT SUMMARY Memories can last the entire lifetime of an organism. Dynamic communication among billions of neurons at synapses underlies information processing and enables the coding and storage of memory. Changes in synapse strength and structure through synaptic plasticity are widely speculated as the cellular basis of memory formation and storage. Studies have identified cellular signaling events and molecular rearrangements underlying the initiation of synaptic plasticity. However, considerably less is known regarding the molecular basis enabling synaptic strength and memories to persist for extended periods of time. While initial synaptic plasticity and long-term memory coding requires protein synthesis, following a period of consolidation, memory storage becomes independent of protein synthesis or neural activity, suggesting that the memory is stored in a remarkably stable molecular entity. During this time, however, most of the individual proteins that are known to make up the synapse will turnover, being degraded and replaced within hours to a few days. Therefore the question remains as to what physical substrates underlie the persistence of long-lasting memories. One possibility is that exceptionally long-lived proteins (LLPs) reside in synapses and act as molecular anchors to maintain the synaptic strength or a network property that defines a given memory. While previous studies have demonstrated the existence of LLPs in the central nervous system, particularly in the nuclei of non-dividing cells, no studies to date have addressed whether such proteins exist at synapses and contribute to the establishment and maintenance of long-term memories. To investigate this hypothesis we designed an unbiased, proteomics-based approach to identify LLPs resident in synapses and characterize their neuronal function. Stable isotope metabolic pulse-chase labeling will be used both in vivo and in vitro to measure the half-lives of the neuronal and synaptic proteomes. These experiments will further be combined with behavioral and pharmacological manipulations to examine how memory formation and neuronal activity influence protein turnover. Identified candidate proteins will be characterized using biochemical, cell-biological, electrophysiological, imaging and behavioral methodologies to determine how these LLPs contribute to synaptic/neuronal function and memory. Within the metabolically active environment of the cell it is known that proteins can undergo oxidative damage. Such damage to LLPs could be a source of vulnerability that may contribute to functional decline during aging. The experiments described in this proposal will significantly contribute to our understanding of LLP functions in the brain and their potential role in for memory formation, long-term storage and age-related cognitive decline.