Role of protein synthesis in Alzheimers disease-associated impairments of synaptic plasticity and memory

阿尔茨海默病(AD)病理生理学的基本细胞/分子信号机制是 不太了解；这种知识的差距正在阻碍我们找到任何有效的治疗方法。 越来越多的证据表明，突触功能受损是AD发病机制中的一个关键事件。然而， 阿尔茨海默病相关突触功能障碍/衰竭的分子机制仍不清楚。我们最近 据报道，翻译因子真核延长因子2(EEF2)的mRNA在AD脑中过度磷酸化。 EEF2被其(唯一已知的)激酶eEF2K磷酸化导致从头合成蛋白质的抑制， 这对于持久的突触可塑性和记忆是必不可少的。在初步数据的推动下， 在本应用中要检验的中心假设是从头蛋白的能力的恢复 通过抑制eEF2K，从而抑制eEF2的磷酸化，合成将缓解AD相关的突触衰竭 以及记忆力受损。已经设计了三个具体的目标来检验这一假设。目标1寻求 确定通过抑制eEF2K活性恢复正常的eEF2磷酸化是否可以挽救 海马长时程突触可塑性中的AD相关损伤。目标2是确定是否 抑制eEF2K活性可改善AD模型小鼠的学习记忆障碍。目标3是确定 抑制eEF2激酶能否减轻AD相关的从头蛋白合成损伤 活动。该项目提出了使用神经科学中多种最先进的方法进行深入分析，包括 突触电生理学、共聚焦成像、小鼠遗传学和行为测试。我们还将雇佣两名 评估脑片从头合成蛋白质的新型非放射性方法：表面传感 翻译(日落)和生物正交非规范氨基酸标记(BONCAT)。这些新方法 将与质谱学/蛋白质组学方法相结合来揭示AD大脑中蛋白质的身份 其合成受eEF2K/eEF2信号异常的影响。这个项目的发现将 对阿尔茨海默病发病的细胞/分子信号机制提供重要数据。 未来的研究将建立在该项目的结果和我们对AD相关蛋白质的其他研究成果的基础上 合成失调为最终开发新的诊断标记物和更好的治疗提供信息 治疗AD相关认知综合征的策略，目前尚无有效的治疗方法。

The basic cellular/molecular signaling mechanisms underlying Alzheimer’s disease (AD) pathophysiology are not well understood; this gap in knowledge is hampering our ability to find any effective therapies. Accumulating evidence indicates impaired synaptic function as a key event in AD pathogenesis. However, the molecular mechanisms underlying AD-associated synaptic dysfunction/failure remain elusive. We recently reported hyperphosphorylation of mRNA translational factor eukaryotic elongation factor 2 (eEF2) in AD brains. Phosphorylation of eEF2 by its (only known) kinase eEF2K results in repression of de novo protein synthesis, which is essential for long-lasting forms of synaptic plasticity and memory. Driven by the preliminary data, the central hypothesis to be tested in this application is that restoration of the capacity for de novo protein synthesis, via inhibition of eEF2K and thus eEF2 phosphorylation, will alleviate AD-associated synaptic failure and memory impairments. Three specific aims have been designed to test this hypothesis. Aim 1 seeks to determine whether restoration of normal eEF2 phosphorylation, via suppressing eEF2K activity, can rescue AD-associated impairments in hippocampal long-term synaptic plasticity. Aim 2 is to determine whether inhibition of eEF2K activity improves learning and memory deficits in AD mouse model. Aim 3 is to determine whether AD-associated impairments of de novo protein synthesis can be mitigated by inhibiting eEF2 kinase activity. The project proposes in-depth analyses using multiple state-of-art methods in neuroscience, including synaptic electrophysiology, confocal imaging, mouse genetics, and behavioral tests. We will also employ two new types of non-radioactive methods to assess de novo protein synthesis in brain slices: surface sensing of translation (SUnSET) and bioorthogonal noncanonical amino acid tagging (BONCAT). These novel methods will be combined with mass spectrometry/proteomics approach to reveal identities of proteins in AD brains whose synthesis is dysregulated because of abnormal eEF2K/eEF2 signaling. Findings from this project will contribute important data regarding the cellular/molecular signaling mechanisms underlying AD pathogenesis. Future studies will build on the results from this project and our other research findings on AD-related protein synthesis dysregulation to inform eventual development of novel diagnostic markers and better therapeutic strategies for AD-related cognitive syndromes, for which no effective treatments exist.