Neuron and microglia-specific proteomic signatures of ERK mediated mechanisms of Alzheimer’s disease

阿尔茨海默病（Alzheimer's disease，AD）是最常见的神经退行性疾病，神经元和小胶质细胞在其发病机制中起着独特的作用。AD的这些细胞机制需要在单个脑细胞类型的水平上解决，特别是在蛋白质（蛋白质组学）水平上，以最好地指导治疗和生物标志物的发现。我们最近对人类死后大脑的蛋白质组学研究已经确定了一种称为MAPK/ERK通路的信号通路，作为AD病理学和认知能力下降的强有力预测因子。我们还发现，ERK途径的活化是AD病理学小鼠模型中活化的小胶质细胞的特征，并且小胶质细胞中ERK的抑制降低了它们的促炎和有害反应。基于这些发现，我们的总体假设是，过度ERK激活是AD发病机制的中心机制，其独特地影响神经元和小胶质细胞的蛋白质组表型，导致神经变性。为了确定MAPK/ERK信号如何在小鼠模型中随着衰老和AD病理学而变化，我们将应用一种称为CIBOP-MS的新型体内标记方法，该方法使我们能够定义小胶质细胞或神经元中特异性发生的蛋白质组学变化的动态，而无需进行细胞类型分离（目的1）。使用ERK活性的小分子抑制剂，我们将确定ERK抑制如何影响神经元和小胶质细胞蛋白质组，并在淀粉样蛋白β小鼠模型中鉴定新的生物流体生物标志物（Aim 2）。最后，我们将使用遗传方法操纵ERK活性，导致神经元或小胶质细胞中的过度激活或特异性衰减（目的3）。总的来说，我们的全面研究集中在神经元和小胶质细胞中的ERK信号传导，将验证CIBOP-MS作为一种新的方法来解决衰老和神经退行性变中脑细胞类型特异性蛋白质组动力学，具有生物标志物和治疗意义。我们在体内细胞类型特异性蛋白质组标记方法、系统生物学、神经炎症、生物流体生物标志物发现和AD病理学小鼠模型方面的多学科专业知识使我们能够执行这项创新的R 01提案。

Alzheimer's disease (AD) is the most common neurodegenerative disease in which neurons and microglia play causal and distinctive roles in its pathogenesis. These cellular mechanisms of AD need to be resolved at the level of individual brain cell types, especially at the protein (proteomic) level to best guide therapeutic and biomarker discovery. Our recent proteomic studies of human post-mortem brains have identified a signaling pathway called the MAPK/ERK pathway, as a strong predictor of AD pathology and cognitive decline. We have also found that activation of the ERK pathway is characteristic of activated microglia in a mouse model of AD pathology, and inhibition of ERK in microglia reduces their pro-inflammatory and detrimental responses. Based on these findings, our overall hypothesis is that excessive ERK activation is a central mechanism of AD pathogenesis that uniquely impacts the proteomic phenotypes of neurons and microglia, leading to neurodegeneration. In order to determine how MAPK/ERK signaling changes with aging and AD pathology in a mouse model, we will apply a novel in-vivo labeling approach called CIBOP-MS that enables us to define the dynamics of proteomic changes occurring specifically in microglia or neurons without the need for cell type isolation (Aim 1). Using a small molecule inhibitor of ERK activity, we will then determine how ERK inhibition impacts neuronal and microglial proteomes and identify novel biofluid biomarkers in an amyloid beta mouse model (Aim 2). Lastly, we will manipulate ERK activity leading to either over-activation or attenuation specifically in either neurons or microglia using genetic approaches (Aim 3). Collectively, our comprehensive studies focusing on ERK signaling in neurons and microglia, will validate CIBOP-MS as a novel approach to resolve brain cell type-specific proteome dynamics in aging and neurodegeneration, with biomarker and therapeutic implications. Our multidisciplinary expertise in in-vivo cell type specific proteomic labeling approaches, systems biology, neuroinflammation, biofluid biomarker discovery and mouse models of AD pathology uniquely positions us to execute this innovative R01 proposal.