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/分子信号传导机制是 不太理解；这种知识差距阻碍了我们寻找有效疗法的能力。 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， AD 相关突触功能障碍/失败的分子机制仍然难以捉摸。我们最近 据报道，AD 大脑中 mRNA 翻译因子真核延伸因子 2 (eEF2) 过度磷酸化。 eEF2 通过其（唯一已知的）激酶 eEF2K 磷酸化，导致蛋白质从头合成受到抑制， 这对于持久的突触可塑性和记忆至关重要。在初步数据的推动下， 本申请要测试的中心假设是从头蛋白质能力的恢复 通过抑制 eEF2K 的合成以及 eEF2 磷酸化，将减轻 AD 相关的突触衰竭 和记忆障碍。设计了三个具体目标来检验这一假设。目标 1 旨在 确定是否可以通过抑制 eEF2K 活性来恢复正常的 eEF2 磷酸化 AD 相关的海马长期突触可塑性损伤。目标 2 是确定是否 抑制 eEF2K 活性可改善 AD 小鼠模型的学习和记忆缺陷。目标 3 是确定 是否可以通过抑制 eEF2 激酶来减轻 AD 相关的从头蛋白质合成损伤 活动。该项目提出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、共焦成像、小鼠遗传学和行为测试。我们还将雇佣两名 评估脑切片中从头蛋白质合成的新型非放射性方法：表面传感 翻译（SUnSET）和生物正交非规范氨基酸标签（BONCAT）。这些新颖的方法 将与质谱/蛋白质组学方法相结合，揭示 AD 大脑中蛋白质的身份 由于 eEF2K/eEF2 信号传导异常，其合成失调。该项目的调查结果将 提供有关 AD 发病机制的细胞/分子信号传导机制的重要数据。 未来的研究将建立在该项目的结果以及我们关于 AD 相关蛋白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 针对 AD 相关认知综合症的策略，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.