Investigating Astrocyte Heterogeneity in the Brain

星形胶质细胞在中枢神经系统(CNS)的发育和功能中起着关键作用，对离子/神经递质的动态平衡、突触传递/可塑性、神经元的代谢支持和血脑屏障起着至关重要的作用。星形胶质细胞是一种异质细胞群体，其特性因发育来源、细胞位置和对环境提示的敏感性而有所不同。然而，星形胶质细胞如何在分子、结构和功能上多样化以发挥其作用仍然知之甚少。在这项探索基金中，我们将使用先进的细胞移植技术来研究这个问题，这种技术使我们能够操纵和跟踪大脑中星形胶质细胞的特性。我们的长期研究愿景是确切地破译中枢神经系统中星形胶质细胞如何、何时以及为什么多样化。要实现的具体目标：目标1：研究促进星形胶质细胞发育和多样化的细胞自主和非细胞自主机制。在大脑中发现了两种广泛类型的星形细胞异质性，它们与脑区之间(区域间多样性)和脑区内(区域内多样性)细胞群的差异有关。然而，创造这种多样性的机制仍然不清楚。我们开发了一种细胞移植方法来研究星形胶质细胞如何在体内整合、成熟和存活。在发育过程中移植到皮质的皮质星形胶质细胞具有类似宿主星形胶质细胞的结构/分子特征，包括领土的形成、血管系统上的末端和突触周围的突起。有趣的是，移植到小脑的皮质星形胶质细胞保留了皮质星形胶质细胞的特征。在目标1中，我们将梳理细胞自主(内在)和非细胞自主(环境)的机制，它们决定了移植的星形胶质细胞的结构/分子/生理多样性。目标2：确定发育和表观遗传状态如何影响移植的星形胶质细胞在中枢神经系统获得特定分子和结构特征的能力。转录因子模式有助于中枢神经系统中区域特异性星形细胞的特性。然而，皮质星形胶质细胞的发育时间窗尚不清楚。根据我们的结果和大脑皮质星形胶质细胞分化/迁移/成熟的时间，我们怀疑胶质前体细胞的特征发生在啮齿类动物的胚胎晚期/出生后早期，并建立了皮质星形胶质细胞的特征。在目标2中，我们将研究皮质星形胶质细胞的发育和表观遗传状态如何使它们获得区域特有的分子/结构特征。结论：这笔赠款将为对脑细胞多样性感兴趣的学生提供出色的概念培训，并提供尖端技术方面的技术培训，如细胞移植、钙成像、RNA和ATAC-SEQ、生物信息学和电生理学。

Astrocytes play critical roles in central nervous system (CNS) development and function and are essential for ion/neurotransmitter homeostasis, synaptic transmission/plasticity, metabolic support for neurons, and contributing to the blood brain barrier.  Astrocytes are a heterogeneous cell population with properties that vary depending on developmental origin, cell positioning, and sensitivity to environmental cues. However, precisely how astrocytes molecularly, structurally, and functionally diversify to perform their roles remains poorly understood. In this Discovery Grant, we will investigate this question using advanced cell transplantation techniques that enables us to manipulate and track the properties of astrocytes in the brain. Our long-term research vision is to decipher exactly how, when, and why astrocytes diversify in the CNS. Specific Objectives to be Achieved: Objective 1: Investigate cell-autonomous and non-cell-autonomous mechanisms that promote astrocyte development and diversification. Two broad types of astrocytic heterogeneity are recognized in the brain related to differences in cell populations between brain regions (inter-regional diversity) and within a brain region (intra-regional diversity). However, mechanisms creating such diversity remain unclear. We developed a cell transplantation approach to study how astrocytes integrate, mature, and survive in vivo. Cortical astrocytes transplanted to cortex during development acquire structural/molecular features that resemble host astrocytes including the formation of territories, endfeet on vasculature, and perisynaptic processes. Interestingly, cortical astrocytes transplanted into cerebellum retain cortical astrocyte features. In Objective 1, we will tease apart cell-autonomous (intrinsic) and non-cell-autonomous (environmental) mechanisms that determine the structural/molecular/physiological diversity of transplanted astrocytes. Objective 2: Determine how developmental and epigenetic states impact the ability of transplanted astrocytes to acquire specific molecular and structural features in the CNS. Transcription factor patterning contributes to region-specific astrocytic properties in the CNS. However, the developmental time window for cortical astrocyte specification is unclear. Based upon our results and the timing of astrocytic differentiation/migration/maturation in cortex, we suspect that glial progenitor specification occurs during a late-embryonic/early postnatal period in rodents and establishes cortical astrocyte signatures. In Objective 2, we will investigate how developmental and epigenetic states of cortical astrocytes enable them to acquire region-specific molecular/structural features. CONCLUSION: This grant will provide outstanding conceptual training for students interested in brain cell diversity and technical training in cutting-edge techniques such as cell transplantation, Ca2+ imaging, RNA- and ATAC-seq, bioinformatics, and electrophysiology.