Cell Type and Regional Vulnerability in Frontotemporal Dementia

项目摘要/摘要 颈椎病研究中的一个关键问题是，为什么一些脑细胞群受到显著影响，而另一些脑细胞群则受到显著影响 相对幸免于难。这项研究的长期目标是了解这种差异细胞的脆弱性和使用 开发保护神经细胞免受直肠肌萎缩症相关变性的疗法的知识。 编码Tau的MAPT基因突变通常会导致前脑的广泛病理， 额叶和颞叶大脑皮层细胞的显著丧失导致行为、语言和 认知缺陷。然而，MAPT突变的一个子集也会导致中脑的显著退化 黑质中的多巴胺能神经元参与了帕金森病的表型。此外，这些细胞 是相互联系的：中脑多巴胺能神经元广泛地支配前额叶皮质，并相互作用 通过皮质-纹状体-黑质环路支配。为什么特定的MAPT突变会显著影响 除了皮质，而其他区域不是，以及这些区域之间的连接如何具有潜在的 可能涉及病理性tau传播，代表着我们将在此解决的知识上的重大差距 建议的研究。 在过去的几年里，我们帮助创建了一个大型的IPSC系列库，收集了家族性 由MAPT基因突变引起的痴呆，包括同基因对照。表型分析显示MAPT 突变型和对照IPSC来源的大脑皮质细胞最初表型相似，但发展不同 随着成熟，包括tau聚集增加，tau过度磷酸化和易感性 与突变相关的压力源。然而，到目前为止，比较前脑和中脑细胞的研究 MAPT突变对这些脑区产生不同影响的群体反应尚未完成。是这样的 比较有可能揭示构成细胞基础的共同和独特的分子机制 脆弱性。 我们的方法是使用人类IPSC衍生的3D有机化合物，它概括了复杂的细胞-细胞 在人体细胞系统中相互作用，并能够在几个月内进行长期培养。我们将创建大脑皮层 和来自两个主要影响皮质的MAPT突变和两个同时影响皮质和 中脑，与各自的同基因对照。在目标1中，我们将研究这些MAPT突变对 用单细胞转录组分来确定细胞类型的多样性 对每一种突变做出反应。在目标2中，我们将创建皮质和中脑有机体的组合体来模拟 并确定这种连通性是否改变了细胞易损性的模式 根据特定的MAPT突变，使病理性tau从一个区域传播到另一个区域。在AIM 3我们将探讨刺激tau降解对大脑皮层分化细胞脆弱性的影响 中脑。

Project Summary/Abstract A key question in tauopathy research is why some brain cell populations are significantly affected while others are relatively spared. The long-term goal of this study is to understand this differential cell vulnerability and use the knowledge to develop therapies that protect neural cells from tauopathy-related degeneration. Mutations in the MAPT gene that encodes Tau commonly cause extensive pathology in the forebrain, with significant loss of frontal and temporal lobe cerebral cortical cells leading to behavioral, language and cognitive deficits. However, a subset of MAPT mutations also cause significant degeneration of midbrain dopaminergic neurons in the substantia nigra contributing to a parkinsonism phenotype. Furthermore, these cells are connected: midbrain dopaminergic neurons widely innervate the prefrontal cortex and are reciprocally innervated via cortico-striatal-nigral circuits. Why specific MAPT mutations significantly affect the midbrain in addition to cortex while others do not, and how connectivity between these regions with the potential for pathological tau spread may be involved, represent significant gaps in knowledge that we will address in this proposed study. Over the past few years, we have helped create a large iPSC line collection from patients with familial dementia due to mutations in the MAPT gene, including isogenic controls. Phenotypic analyses show MAPT mutant and control iPSC-derived cerebral cortical cells are initially phenotypically similar but develop differences with maturation that include increased tau aggregation, tau hyperphosphorylation and vulnerability to several stressors, associated with the mutation. However, to date, studies comparing forebrain and midbrain cell population responses to MAPT mutations that differentially affect these brain regions have not been done. Such comparisons have the potential to reveal common and unique molecular mechanisms that underlie cell vulnerability. Our approach is to use human iPSC-derived 3D organoids, which recapitulate complex cell-cell interactions in a human cell system and enable long-term culture over several months. We will create cortical and midbrain organoids from two MAPT mutations that primarily affect cortex and two that affect both cortex and midbrain, versus respective isogenic controls. In Aim 1 we will examine the impact of these MAPT mutations on cell populations and gene expression over time using single cell transcriptomics to define how diverse cell types respond to each mutation. In Aim 2, we will create assembloids of cortical and midbrain organoids to model the circuitry between the regions and determine whether this connectivity alters patterns of cell vulnerability and enables the spread of pathological tau from one region to another, depending on specific MAPT mutation. In Aim 3 we will probe the impact of stimulating tau degradation on differential cell vulnerability in cerebral cortex and midbrain.