Circadian changes in network excitability and Alzheimer disease pathogenesis

项目摘要 越来越多的证据表明，神经元和网络的过度兴奋是一个重要的早期事件， 阿尔茨海默病（AD）患者。这种超兴奋性的细胞和分子基础是一个关键领域， 研究和动物模型中类似的过度兴奋的存在使得研究能够剖析 基本机制。一个关键的见解是，在AD患者和小鼠模型中的过度兴奋都有一个重要的作用。 强烈的昼夜节律新出现的数据还表明，前脑的神经兴奋性通常低于 控制生物钟，调节癫痫发作阈值和癫痫样活动的易感性。 细胞功能的昼夜变化是由大多数细胞中表达的转录分子钟驱动的， 分子钟消融增加AD病理。我们有令人信服的初步证据 神经元兴奋性的变化，至少部分是由于细胞膜特性的昼夜节律调节， 抑制性中间神经元，特别是表达小清蛋白（PV）的快速尖峰细胞。鉴于PV+中间神经元 在大脑皮层和齿状回中的异常与AD密切相关，并且昼夜节律在AD中被破坏， 患者和AD小鼠模型，我们提出了严格的实验来验证这一假设，即失调的 分子钟和PV+中间神经元基因表达和活性的变化有助于AD- 相关的神经元过度兴奋。具体来说，我们将评估生物钟和生物钟的差异- 在AD的小鼠模型中，PV+中间神经元与兴奋性神经元中的受控基因表达，使用 RNA测序，最先进的生物信息学和最近开发的工具相结合，以评估 分子钟节律性和转录在细胞特异性的方式（目的1）。我们将记录从抑制 以及齿状回和皮质中的兴奋性神经元，以确定PV+抑制性的时钟驱动变化是否 神经元活动在AD模型中被破坏，并导致总体过度兴奋（Aim 2）。最后我们将 利用创新的化学发生学计时方法来操纵PV+中间神经元生理学， 确定恢复AD小鼠中PV+中间神经元活动的正常昼夜节律模式是否能保护 针对过度兴奋、认知障碍和病理学（目的3）。拟议的研究由一个强大的 跨学科团队使用强有力方法来确定昼夜节律的破坏如何促进 导致AD早期的神经元过度兴奋。了解这些机制可能 促进行为或药物干预的发展。

PROJECT SUMMARY Converging evidence indicates that neuronal and network hyperexcitability is an important early event in Alzheimer’s disease (AD) patients. The cellular and molecular basis of this hyperexcitability is a critical area of investigation and the presence of similar hyperexcitability in animal models enables studies to dissect underlying mechanisms. A key insight is that hyperexcitability in both AD patients and mouse models has a strong diurnal rhythm. Emerging data also indicate that neural excitability in the forebrain is normally under control of the circadian clock, which regulates seizure thresholds and susceptibility to epileptiform activity. Circadian variation in cellular function is driven by transcriptional molecular clocks expressed in most cells, and molecular clock ablation increases AD pathology. We have compelling preliminary evidence for rhythmic variation in neuronal excitability that is at least partly due to circadian regulation of the membrane properties of inhibitory interneurons, especially fast-spiking cells expressing parvalbumin (PV). Given that PV+ interneurons in the cortex and dentate gyrus are strongly implicated in AD, and that circadian rhythms are disrupted in AD patients and AD mouse models, we propose rigorous experiments to test the hypothesis that dysregulation of the molecular clock and resulting changes in PV+ interneuron gene expression and activity contribute to AD- related neuronal hyperexcitability. Specifically, we will evaluate the differences in circadian clock and clock- controlled gene expression in PV+ interneurons vs. excitatory neurons in the mouse models of AD, using a combination of RNA sequencing, state-of-the-art bioinformatics, and recently developed tools to evaluate molecular clock rhythmicity and transcription in a cell-specific manner (Aim 1). We will record from inhibitory and excitatory neurons in the dentate gyrus and cortex to determine if clock-driven changes in PV+ inhibitory neuron activity are disrupted in AD models and contribute to overall hyperexcitability (Aim 2). Finally, we will utilize an innovative chemogenetic chronotherapeutic approach to manipulate PV+ interneuron physiology to determine whether reinstating the normal circadian patterns of PV+ interneuron activity in AD mice protects against hyperexcitability, cognitive impairment, and pathology (Aim 3). The proposed studies led by a strong interdisciplinary team use powerful approaches to determine how disruption of circadian rhythms facilitates neuronal hyperexcitability that contributes to early stages of AD. Understanding these mechanisms may catalyze development of behavioral or pharmacologic interventions.