Single Cell Analyses of Neuroimmune Dysfunctions in the Thalamocortical Circuit in FTLD

项目总结 异常的神经胶质细胞激活是神经退行性疾病的一个显著特征。但是，是什么触发了神经胶质 老化大脑中的激活以及它如何导致神经元退化仍不清楚。科学的 这一建议的前提是基于先前的研究，即人类原颗粒基因的显性突变 (GRN[基因]，PGRN[蛋白质])导致患者脑脊液和脑组织中的PGRN水平急剧下降 伴额颞叶变性(FTLD)，导致深度胶质增生，RNA结合蛋白聚集 TDP-43和神经退行性变。为了支持这一观点，我们最近的研究表明，Grn基因敲除(Grn-/-) 小鼠是捕捉由GRN突变引起的FTLD的几个关键疾病特征的有效模型(FTLD- GRN)，包括小胶质细胞激活、小胶质细胞介导的突触修剪和功能障碍 丘脑皮质回路。我们正在进行的工作进一步表明，Grn-/-小鼠和FTLD-GRN患者也显示 强健的星形胶质细胞激活与小胶质细胞激活呈正相关。与Grn-/-小胶质细胞类似，Grn-/- 星形胶质细胞表现出与年龄相关的先天免疫基因上调，包括补体C3和 C4b与来自Grn-/-小胶质细胞的C1qa一起激活经典和替代补体 促进神经退化的途径。综上所述，这些结果支持了PGRN的假设 缺乏是一个可行的疾病模型，以揭示复杂的神经免疫相互作用和如何扰动 这些相互作用会导致神经元退化。为了检验这一假设，我们提出了一个全面的 用单细胞转录法观察大鼠脑内神经胶质细胞和神经细胞类型的动态变化 受PGRN缺乏影响最严重的丘脑皮质回路。这种方法将提供关键的 神经胶质细胞激活、神经元变性和神经回路功能障碍的内在机制 GRN-/-小鼠和FTLD-GRN患者。这一创新战略涉及高吞吐量分析 基于液滴捕获技术的神经胶质细胞和神经元的转录和生理特性， 细胞内在生理反应的显微镜和动态成像。这些结果将提供一个 史无前例的分辨率，直接测试破坏动态神经免疫的假说 丘脑皮质环路中小胶质细胞、星形胶质细胞和神经元之间的相互作用导致神经变性 由PGRN缺乏引起的FTLD。

PROJECT SUMMARY Aberrant glial activation is a prominent feature in neurodegenerative diseases. But, what triggers glial activation in the aging brain and how it contributes to neuronal degeneration remains unclear. The scientific premise of this proposal is based on previous studies that dominant mutations in human Progranulin gene (GRN [gene], PGRN [protein]) cause a drastic reduction in PGRN levels in CSF and brain tissues in patients with frontotemporal lobar degeneration (FTLD), leading to profound gliosis, aggregation of RNA binding protein TDP-43, and neurodegeneration. In support of this idea, our recent studies show that Grn knockout (Grn-/-) mice is a valid model that captures several key disease features in FTLD caused by GRN mutations (FTLD- GRN), including microglial activation, microglia-mediated synaptic pruning and dysfunction in the thalamocortical circuit. Our ongoing work further revealed that Grn-/- mice and FTLD-GRN patients also shows a robust astroglial activation that positively correlates with microglial activation. Similar to Grn-/- microglia, Grn-/- astrocytes exhibit an age-dependent up-regulation of innate immunity genes, including complements C3 and C4b, which together with C1qa from Grn-/- microglia, activate both classical and alternative complement pathways to promote neurodegeneration. Taken together, these results support the hypothesis that PGRN deficiency is a feasible disease model to uncover the intricate neuroimmune interactions and how perturbation to these interactions leads to neuronal degeneration. To test this hypothesis, we propose a comprehensive single cell transcriptomic approach to survey the dynamic changes of glial and neuronal cell types in the thalamocortical circuit that is most severely impacted by PGRN deficiency. This approach will provide critical insights into the intrinsic mechanism of glial activation, neuronal degeneration and neural circuit dysfunction in Grn-/- mice and in FTLD-GRN patients. This innovative strategy involves high throughput profiling of transcriptomic and physiological properties of glia and neurons using droplet-based capture technology, microscopy and dynamic imaging of cell intrinsic physiological responses. These results will provide an unprecedented resolution to directly test the hypothesis that disruptions to the dynamic neuroimmune interactions between microglia, astrocytes and neurons in the thalamocortical circuit lead to neurodegeneration in FTLD caused by PGRN deficiency.