Impaired activity-dependent protein synthesis in dendrites and pathophysiology in tauopathy

项目概要/摘要 阿尔茨海默病和相关痴呆中的致病性tau蛋白抑制神经元连接的可塑性 潜在的渐进性记忆丧失然而，尚未确定的是， 在具有致病性tau的神经元中破坏突触可塑性的分子事件。这是我们的主要差距。 了解阿尔茨海默病记忆丧失的分子和生理过程， 相关的痴呆症有一个关键的需要，以揭示可塑性是如何失调的致病性tau蛋白奠定了 为针对可塑性进行治疗干预这些疾病的新策略奠定基础。长期 增强（LTP）是一种可塑性，涉及持续加强特定的连接， 神经元对活动增加的反应。记忆障碍和阻塞之间有很强的联系 在阿尔茨海默病和相关痴呆症的转基因小鼠模型中，突触的LTP，表明 突触不能表达LTP是导致记忆衰退的关键因素。我们的初步研究表明 致病性tau蛋白阻断了树突中活性依赖性的从头蛋白合成，而这种合成是LTP所必需的， 表情此外，我们发现致病性tau蛋白下调了一个翻译起始因子， 可塑性过程中的活性依赖性mRNA翻译。这一提议的核心假设是， tau蛋白阻断树突中局部蛋白质翻译的起始，从而破坏突触后神经元的动力学。 建立LTP和编码新记忆的蛋白质。为了阐明致病的机制， tau抑制LTP表达，我们建议使用人诱导多能干细胞（iPSC）衍生的培养的 具有家族性tau突变V337 M和R406 W的神经元，其导致痴呆和PS19 tau蛋白病小鼠 模型我们将建立致病性tau蛋白对mRNA主动翻译成新合成的 LTP表达过程中的蛋白质我们将使用多种方法的组合来监测tau蛋白对肿瘤发生率的影响。 蛋白质合成和在LTP期间活跃翻译的mRNA子集。我们接下来将决定 致病性tau蛋白对蛋白质翻译起始的关键步骤的影响，以及 恢复活性依赖的翻译起始可以改善PS19小鼠的LTP和记忆障碍 通过电生理记录和学习记忆行为测试进行评估。最后，我们将使用 一种公正和创新的APEX蛋白质组学方法，以确定致病性tau蛋白对动态 LTP表达过程中突触后蛋白组成的变化，包括从头蛋白 合成和重组蛋白质组成以增强突触强度。通过这些研究，我们 期望阐明致病性tau蛋白对树突蛋白合成的影响以及对突触后神经元的调节， 蛋白质动力学是阿尔茨海默病记忆丧失的复杂和多因素原因的基础， 相关的痴呆症

PROJECT SUMMARY/ABSTRACT Pathogenic tau in Alzheimer’s disease and related dementias inhibits the plasticity of neuronal connections underlying progressive memory loss. What remains undetermined, however, are the complex and multifactorial molecular events that disrupt synaptic plasticity in neurons with pathogenic tau. This is major gap in our knowledge of the molecular and physiological processes underlying memory loss in Alzheimer’s disease and related dementias. There is a critical need to uncover how plasticity is dysregulated by pathogenic tau to lay the groundwork for new strategies to target plasticity for therapeutic intervention in these diseases. Long-term potentiation (LTP) is a type of plasticity that involves the persistent strengthening of specific connections between neurons in response to increased activity. There is a strong link between memory impairments and obstructed LTP at synapses in transgenic mouse models of Alzheimer’s disease and related dementias, suggesting that the inability of synapses to express LTP is a key factor leading to memory decline. Our preliminary studies suggest that pathogenic tau blocks the activity-dependent de novo protein synthesis in dendrites that is required for LTP expression. Moreover, we found that pathogenic tau downregulates a translation initiation factor that controls activity-dependent mRNA translation during plasticity. The central hypothesis of this proposal is that pathogenic tau blocks the initiation of local protein translation in dendrites and thereby disrupts the dynamics of postsynaptic proteins that establish LTP and the encoding of new memories. To delineate the mechanism by which pathogenic tau inhibits LTP expression, we propose to use both human induced pluripotent stem cell (iPSC)-derived cultured neurons with familial tau mutations, V337M and R406W, that cause dementia and the PS19 tauopathy mouse model. We will establish the effect of pathogenic tau on the active translation of mRNAs into newly synthesized proteins during LTP expression. We will use a combination of methods to monitor the effect of tau on the rate of protein synthesis and on the subset of mRNAs that are actively translated during LTP. We will next determine the impact of pathogenic tau on a critical step in the initiation of protein translation and the extent to which restoring activity-dependent translation initiation can ameliorate LTP and memory impairments in PS19 mice assessed by electrophysiological recordings and behavioral tests of learning and memory. Finally, we will use an unbiased and innovative APEX proteomics approach to establish the impact of pathogenic tau on the dynamic changes in the postsynaptic protein composition during LTP expression that involve both de novo protein synthesis and the reorganization of protein composition to enhance synaptic strength. From these studies, we expect to elucidate the effect of pathogenic tau on dendritic protein synthesis and the regulation of postsynaptic protein dynamics that underlie the complex and multifactorial causes of memory loss in Alzheimer’s disease and related dementias.