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

阿尔茨海默病（AD）病理生理学基础的基本细胞/分子信号传导机制是 没有得到很好的理解;这种知识上的差距阻碍了我们找到任何有效疗法的能力。 越来越多的证据表明突触功能受损是AD发病机制中的关键事件。但 AD相关的突触功能障碍/失败的分子机制仍然难以捉摸。我们最近 报道了AD脑中mRNA翻译因子真核延伸因子2（eEF 2）的过度磷酸化。 eEF 2通过其（唯一已知的）激酶eEF 2K的磷酸化导致从头蛋白质合成的抑制， 这对于突触可塑性和记忆的持久形式至关重要。在初步数据的推动下， 在本申请中待检验中心假设是重新形成蛋白质的能力的恢复 通过抑制eEF 2K的合成，从而抑制eEF 2的磷酸化，将减轻AD相关的突触失效 和记忆障碍为了检验这一假设，设计了三个具体目标。目标1： 确定通过抑制eEF 2K活性恢复正常的eEF 2磷酸化是否可以挽救 海马长期突触可塑性的AD相关损伤。目标2是确定是否 抑制eEF 2K活性改善AD小鼠模型的学习和记忆缺陷。目标3：确定 是否可以通过抑制eEF 2激酶来减轻AD相关的从头蛋白合成损伤 活动该项目建议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。我们还将雇用两名 评估脑切片中从头蛋白质合成的新型非放射性方法： 翻译（SUnSET）和生物正交非规范氨基酸标记（BONCAT）。这些新型方法 将与质谱/蛋白质组学方法相结合，以揭示AD大脑中蛋白质的身份 其合成由于异常eEF 2K/eEF 2信号传导而失调。该项目的结果将 贡献了关于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这个项目的结果和我们对AD相关蛋白的其他研究成果的基础上 合成失调，以告知新的诊断标志物和更好的治疗方法的最终开发 AD相关认知综合征的治疗策略，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.