Deciphering molecular pathways of inhibitory interneuron dysfunction in Alzheimer's disease

自从拉蒙·伊·卡哈尔提出大脑不是一个单一的网状单位，而是包含离散的和独立的 对于脑细胞，神经科学家一直在努力阐明不同脑细胞类型的功能特性。这 细胞异质性，这可能是由特定细胞类型的基因表达程序引起的 突显了神经元群体对神经退行性疾病的选择性脆弱性。然而， 缺乏对特定细胞类型进行分子图谱分析和操作的有效工具阻碍了进展 在确定脆弱细胞群体的疾病机制和开发针对细胞类型的特定疗法方面。AS 开发了新的技术平台来分析神经系统中的特定细胞类型，包括 BacTRAP和单细胞RNA-seq，以及操纵特定神经元中的基因或活动的遗传工具 人口，包括视紫红质依赖和通道系统，新的机会正在出现 在实验上解决体内细胞类型的异质性和选择性脆弱性。我们会带上 利用最新技术识别与脑缺血相关的抑制性中间神经元的分子改变 阿尔茨海默病(AD)小鼠模型和阿尔茨海默病人类模型的认知障碍。我们将特别关注抑制性中间神经元，因为它们可能对人类AD和相关模型的早期脑网络改变(例如，多动和失活缺陷)、淀粉样蛋白β(Aβ)沉积和认知改变起关键作用。在这里，我们建议通过使用BacTRAP和单细胞RNA-seq的转录组图谱，在AD、J20和APP-KI两个小鼠模型中识别与认知相关的神经细胞类型的分子改变，在人类AD样本中验证我们的发现，并在小鼠模型中进行机制研究，以确定已识别的分子改变的功能和治疗相关性。具体地说，AIM 1将确定NTG、J20和APP-KI小鼠行为特征的内源性和移植抑制细胞类型(Mafb-和Dlx1-BacTRAP细胞)的RNA-seq转录组以及行为特征明显的NTG、J20和APP-KI小鼠大脑皮质和海马区的批量RNA-seq转录组。目的2将确定J20和APP-KI小鼠中间神经元亚型全多样性的单细胞RNA-seq转录组图谱(目标2a)，并在AD患者的人类样本中进行验证(目标2b)。AIM 3将通过cre依赖的缺失或过度表达来调节J20小鼠的表达水平，以确定它们对J20小鼠脑网络和认知功能障碍的因果贡献，从而从功能上验证J20小鼠中已发现的分子/途径变化。与我们的初步结果一致，我们预测中间神经元对AD诱导的变化具有细胞类型特异性的脆弱性，其中一些变化与J20小鼠的认知能力下降有关。我们预测这项研究将 产生了重大的科学贡献，将有助于我们了解AD的网络异常和神经元间功能障碍。

Since Ramon y Cajal proposed that the brain is not a single reticular unit but contains discrete and independent brain cells, neuroscientists have struggled to elucidate the functional properties of distinct brain cell types. This cellular heterogeneity, which arises from cell-type-specific gene expression programs, probably underlies the selective vulnerability of neuronal populations to neurodegenerative disorders. However, the lack of effective tools for molecular profiling and manipulation of specific cell types has hampered progress in identifying disease mechanisms of vulnerable cell populations and developing cell-type specific therapies. As new technology platforms are developed to profile specific cell types in the nervous system, including BacTRAP and single-cell RNA-seq, and genetic tools to manipulate genes or activity in specific neuronal populations, including cre-dependent and channelrhodopsin systems, new opportunities are emerging to experimentally address cell-type heterogeneity and selective vulnerability in vivo. We will take advantage of the latest technologies to identify molecular alterations in inhibitory interneurons associated with cognitive impairment in mouse models of Alzheimer's disease (AD) and humans with AD. We will particularly focus on inhibitory interneurons since they may critically contribute to early brain network alterations (e.g., hyperactivity and deactivation deficits), amyloid-β (Aβ) deposition, and cognitive alterations in humans with AD and related models. Here, we propose to identify cognitive-relevant molecular alterations in interneuron cell types in two mouse models of AD, J20 and APP-KI mice, by transcriptome profiling using BacTRAP and single-cell RNA-seq, validate our findings in human AD samples, and perform mechanistic studies in mouse models to determine the functional and therapeutic relevance of the identified molecular alterations. Specifically, Aim 1 will determine the RNA-seq transcriptome profile of genetically defined endogenous and transplanted inhibitory cell types (Mafb- and Dlx1-BacTRAP cells) and bulk RNA-seq transcriptome of the cortex and hippocampus of behaviorally characterized NTG, J20, and APP-KI mice. Aim 2 will determine the single-cell RNA-seq transcriptome profile of the full diversity of interneuron sub-types in J20 and APP-KI mice (Aim 2a) and validate it in human samples of AD (Aim 2b). Aim 3 will functionally validate the identified molecular/pathway alterations in J20 mice by modulating their expression levels by cre-dependent deletions or overexpression to determine their causal contribution to brain network and cognition dysfunction in J20 mice. Consistent with our preliminary results, we predict that interneurons have cell-type-specific vulnerability to AD-induced changes and some of those alterations are causally linked to cognitive decline in J20 mice. we predict this research will generate major scientific contributions that will help us to understand network abnormalities and interneuron dysfunction in AD.