Developing astrocyte, neuron, and microglial 3D organoids to model key aspects of human pathology

项目摘要 星形胶质细胞是大脑中含量最丰富的非神经细胞类型。星形胶质细胞促进神经元存活， 为神经元提供代谢底物，帮助回收突触神经递质，调节血流，缓冲 细胞外离子，诱导或消除突触，调节突触传递和突触可塑性。 最近的研究表明，当特定的信号通路受损时，星形胶质细胞可以 变得有反应性，并最终开始消除突触；在这两种情况下导致神经细胞死亡 自然衰老和与年龄相关的神经退行性疾病。我们的研究旨在了解星云如何 激活在阿尔茨海默病(AD)中启动。我们将通过研究一种名为 颗粒素(GRN)。该基因与人类大脑皮层的衰老有关，GRN的丢失不可避免地导致 星形胶质细胞激活与一种称为额叶的破坏性神经退行性疾病 变性(FTLD)。为了开始解决这个问题，我们建议研究 GRN信号转导星形胶质细胞激活。我们工作的目标是了解正常的GRN是如何发挥作用的 防止健康老化的人类神经元中的蛋白质错误定位，以及GRN的丢失如何导致这些 蛋白质在神经元中的错位：导致AD和FTLD的神经元死亡。根据最近的调查结果， 啮齿动物星形胶质细胞和人类星形胶质细胞在遗传和形态上有很大的不同，我们将使用人类星形胶质细胞 细胞来研究这一问题，并建立一个新的3D人诱导多能干细胞(IPSC)器官系统 以整合人类神经元、星形胶质细胞和小胶质细胞。然后我们将分析特定的错误本地化 GRN阳性和GRN敲除类有机物中的蛋白质。我们还将研究两者之间的信号差异 GRN阳性和GRN基因敲除的星形胶质细胞，并关注天然免疫补体的途径和如何 GRN影响这一途径。总而言之，这些研究将使我们能够确定星形胶质细胞中 促进大脑动态平衡、衰老和疾病。

Project Summary Astrocytes are the most abundant non-neuronal cell types in the brain. Astrocytes promote neuronal survival, provide neurons with metabolic substrates, help recycle synaptic neurotransmitters, regulate blood flow, buffer extracellular ions, induce or eliminate synapses and regulate synaptic transmission and synaptic plasticity. Most recently, it has been shown that when specific signaling pathways are compromised, astrocytes can become reactive and can start eliminating synapses ultimately; leading to neuronal cell death during both natural aging and age-related neurodegenerative diseases. Our research aims to understand how astroglial activation is initiated in Alzheimer’s Disease (AD). We will focus on this question by studying a gene called granulin (GRN). This gene has been linked to aging in the human cortex and loss of GRN inevitably leads to astroglial activation and a devastating neurodegenerative disease termed Frontal Temporal Lobar Degeneration (FTLD). To begin to tackle this question, we propose investigating the molecular mechanisms of GRN signaling on astroglial activation. The goal of our work is to understand how normal GRN function prevents protein mislocalization in healthy aging human neurons, and how loss of GRN causes these same proteins to mislocalize in neurons: leading to neuronal death in AD and FTLD. Based on recent findings that rodent astrocytes and human astrocytes are genetically and morphologically very different, we will use human cells to study this question and set up a novel 3D human induced pluripotent stem cell (iPSC) organoid system to incorporate human neurons, astrocytes and microglia. We will then analyze the mislocalization of specific protein in GRN positive and GRN knockout organoids. We will also study the signaling differences between GRN positive and GRN knockout astrocytes, and focus on the innate immune complement pathway and how GRN affects this pathway. Collectively, these studies will allow us to identify the factors in astrocytes that promote brain homeostasis, aging and disease.