Differential impact of Alzheimer disease on neuronal subpopulations in dorsal hippocampal CA1

项目摘要/摘要 早期阿尔茨海默病(AD)的记忆丧失是当病理生理学从内嗅皮层延伸时出现的 (EC)进入海马区CA1区。CA1处理EC输入以产生海马区输出，并承担 海马区AD病理的首当其冲。对CA1的AD研究将其锥体神经元(PNS)视为 同质人口。然而，我们和其他组织的研究表明，CA1 PNS是多样化的， 由浅层(SPN)和深层(DPN)组成，在记忆中具有独特的作用。这两层显示了 缺血和癫痫的不同变化，但我们在这个水平上对AD病理生理学的了解是 不完整。这限制了我们对阿尔茨海默病记忆缺陷的理解和纠正功能障碍的能力。这 知识还可以促进我们对AD和神经退行性变依赖活动的传播的理解 风险因素。我们发表的和初步的数据，以及文献，支持一个工作假说，背部 由于淀粉样蛋白和tau蛋白，CA1 SPN和DPN表现出截然不同的病理生理和功能损害 病理学。SPN出现衰老的病理迹象，并显示出固有的和突触的低兴奋性。 老龄和3xTg-AD小鼠。DPN不会表现出这些迹象，会变得极度兴奋。在人类AD中， SPN层更容易出现斑块和缠结，两层显示出与蛋白质组相关的差异 疾病途径和兴奋性。我们使用淀粉样蛋白(5xFAD)和tau(PS19)模型来验证我们的假设 分别从三个层面阐述这些病理对SPN/DPN的影响。在目标1中，我们使用体外 光电生理学评估AD病理对背侧SPN和DPN相关回路的影响。 这将把细胞和突触的特性与生理变化的方向性和程度联系起来。我们期待着 淀粉样蛋白/tau可引起SPN回路的低兴奋性和DPN回路的高兴奋性。在目标2中，我们使用 迷你镜GCaMP钙显像确定AD病理对背侧SPN和DPN的影响 在海马区依赖行为中的活动。这将测试差分局部电路的体内优势 在设置记忆缺陷时，CA1的变化在整体上减少了传出输入。我们预计SPN是 在记忆引导的行为中，更容易受到体内活动减少的影响。在目标3中，我们比较 AD病理背景下背侧SPN与DPN的蛋白质组学变化。这将链接小区标识， AD严重程度的分子标志物，以及生理变化的程度/方向性。我们预计SPN 蛋白质组将在病理性AD途径中表现出更严重的变化。这项工作具有重要意义，因为它提供了 关于阿尔茨海默病记忆功能障碍的新的、细胞类型特定的、机械性的知识。这也将有助于链接 生理变化到病理发展和神经退行性变。这些是实现以下目标的关键步骤 更好的治疗方法。我们的战略是创新的，通过结合多种最先进的方法来解决 不同细胞类型在多个生物水平上的疾病病理生理学：电路、行为和分子。

PROJECT SUMMARY/ABSTRACT Memory loss in early Alzheimer disease (AD) appears when pathophysiology extends from entorhinal cortex (EC) into hippocampal area CA1. CA1 processes EC input to generate hippocampal output, and bears the brunt of hippocampal AD pathology. AD studies on CA1 have treated its pyramidal neurons (PNs) as a homogeneous population. However, work from our and other groups established that CA1 PNs are diverse, comprised of superficial (sPN) and deep (dPN) layers with unique roles in memory. The two layers show differential changes in ischemia and epilepsy, but our knowledge of AD pathophysiology at this level is incomplete. This limits our understanding of memory deficits in AD and our ability to correct dysfunction. This knowledge can also advance our understanding of activity-dependent spread of AD and neurodegeneration risk factors. Our published and preliminary data, and the literature, support a working hypothesis that dorsal CA1 sPNs and dPNs exhibit contrasting pathophysiological and functional compromise due to amyloid and tau pathology. The sPNs develop pathologic signs of aging, and show intrinsic and synaptic hypoexcitability in aged and 3xTg-AD mice. The dPNs do not show these signs and become hyperexcitable. In human AD, the sPN layer is more prone to plaques and tangles, and the two layers show proteomic differences related to disease pathways and excitability. We test our hypothesis using amyloid (5xFAD) and tau (PS19) models to separately address the effects of these pathologies on sPNs/dPNs at three levels. In Aim 1, we use in vitro opto-electrophysiology to evaluate the impact of AD pathology on dorsal sPN- versus dPN-associated circuits. This will relate cell and synaptic identity to the directionality and extent of physiologic change. We expect that amyloid/tau induce hypoexcitability in sPN circuits and hyperexcitability in dPN circuits. In Aim 2, we use miniscope GCaMP calcium imaging to determine the influence of AD pathology on dorsal sPN versus dPN activity during hippocampal-dependent behavior. This will test the in vivo dominance of differential local circuit changes in CA1 over globally reduced efferent input in the setting of memory deficits. We expect that sPNs are more vulnerable to reductions in their in vivo activity during memory-guided behaviors. In Aim 3, we compare proteomic changes in dorsal sPNs versus dPNs in the setting of AD pathology. This will link cell identity, molecular markers of AD severity, and the degree/directionality of physiologic change. We expect that sPN proteomes will show more severe changes in pathologic AD pathways. This work is significant by providing new, cell-type specific, mechanistic knowledge about memory dysfunction in AD. This will also help link physiologic change to development of pathology and neurodegeneration. These are critical steps towards better treatments. Our strategy is innovative by combining multiple, state-of-the-art approaches to address disease pathophysiology in distinct cell types at multiple biological levels: circuit, behavior, and molecular.