The role of astrocytes in the pathogenesis of sporadic tauopathy

项目摘要 Tauopathies是一组异质性神经退行性疾病，其特征在于病理学上的 tau蛋白在大脑中的聚集。最常见的原发性tau蛋白病，进行性核上性麻痹 (PSP)临床上被鉴定为进行性帕金森综合征伴核上性凝视麻痹，认知障碍， 功能障碍、行为改变和其他神经缺陷。神经病理学上，PSP有一个星座， 包括形态学上不同的簇状星形胶质细胞（TA）的特征。星形胶质细胞通常不含显著的 tau水平表明TA在PSP中起重要但未知的病理作用。大多数PSP 病例是零星的。全基因组关联研究已经确定了与PSP风险相关的常见变异 在EIF 2AK 3中，其编码对未折叠蛋白至关重要的内质网（ER）应激传感器 答复（普遍定期审议）。有证据表明星形胶质细胞中的ER应激与tau蛋白之间存在致病性关联 积累的PSP，但要测试候选分子机制，有一个模型系统的关键需要 它重现了人类大脑的细胞环境，并保留了人类大脑的遗传复杂性。 疾病开发从PSP患者产生的人诱导多能干细胞（iPSC）衍生模型 将是表征散发性tau蛋白病的分子驱动因素的有力工具。我们假设普遍定期审议 星形胶质细胞中的活化驱动神经变性并在散发性PSP中起关键作用。在我们的第一个目标中，我们将 UPR激活与人死后脑组织中星形胶质细胞病理学和变性相关。 尸检证实PSP脑组织从我们的大集合将染色，成像，并分析p-tau 使用创新的定量方法，实现分配和普遍定期审议的共同定位。在第二个目标中，我们将测试 假设PSP神经元和星形胶质细胞非常容易受到tau病理学的影响， PSP星形胶质细胞增加细胞脆弱性。为了实现这一目标，我们将创建患者iPSC衍生的 单层神经元和星形胶质细胞，并直接测量分子变化和细胞脆弱性， 普遍定期审议的药理学操纵。最后，我们将确定在多大程度上普遍定期审议的激活， 在iPSC衍生的类器官模型中，星形胶质细胞增加了毒性tau物质的产生和细胞脆弱性 偶尔的PSP。这一目标将探索不同细胞群体中的分子扰动，这些分子扰动有助于细胞的增殖。 在3-D细胞环境中发展tau病理学，重现复杂的神经元-星形胶质细胞 在人脑组织中发生的相互作用。这些发现将在配对尸检脑组织中得到验证， 同一个捐赠者。总之，本研究中进行的临床转化研究将产生患者- 衍生的iPSC模型保留了疾病相关的基因组背景，并揭示了候选途径， 在散发性PSP中早期被破坏。

PROJECT SUMMARY Tauopathies are a group of heterogeneous neurodegenerative diseases characterized by pathological aggregation of tau protein in the brain. The most common primary tauopathy, progressive supranuclear palsy (PSP), is identified clinically by progressive parkinsonism with supranuclear gaze paralysis, cognitive dysfunction, behavioral changes, and other neurological deficits. Neuropathologically, PSP has a constellation of features including morphologically distinct tufted astrocytes (TA). Astrocytes normally do not contain significant levels of tau suggesting that TA play an important, but unknown, pathological role in PSP. The majority of PSP cases are sporadic. Genome wide association studies have identified common variants associated with PSP risk in EIF2AK3, which encodes an endoplasmic reticulum (ER) stress sensor critical for the unfolded protein response (UPR). There is evidence for a pathogenic association between ER stress in astrocytes and tau accumulation in PSP, but to test candidate molecular mechanisms there is a critical need for a model system that recapitulates the cellular environment of the human brain and retains the genetic complexity of human disease. Developing human induced pluripotent stem cell (iPSC)-derived models generated from PSP patients will be a powerful tool to characterize molecular drivers of sporadic tauopathy. We hypothesize that UPR activation in astrocytes drives neurodegeneration and plays a key role in sporadic PSP. In our first aim, we will correlate UPR activation with astrocyte pathology and degeneration in human post-mortem brain tissue. Autopsy-confirmed PSP brain tissue from our large collection will be stained, imaged, and analyzed for p-tau distribution and UPR colocalization using innovative quantitative approaches. In the second aim, we will test the hypothesis that PSP neurons and astrocytes are highly vulnerable to tau pathology, and that UPR activation in PSP astrocytes increases cell vulnerability. To accomplish this aim, we will create patient iPSC-derived monolayer neurons and astrocytes and directly measure molecular changes and cell vulnerability by pharmacological manipulation of the UPR. Lastly, we will determine the extent to which UPR activation in astrocytes increases the production of toxic tau species and cell vulnerability in an iPSC-derived organoid model of sporadic PSP. This aim will explore molecular perturbations in different cell populations that contribute to the development of tau pathology in a 3-D cellular environment that recapitulates the complex neuronal-astrocyte interactions that occur in human brain tissue. These findings will be validated in paired autopsy brain tissue from the same donor. In summary, the clinical-translational research performed in this study will generate patient- derived iPSC models that retain a disease-relevant genomic background and reveal candidate pathways that are disrupted early in sporadic PSP.