Control of extracellular matrix remodeling by CD29+ astrocytes

项目总结/摘要 细胞外基质（ECM）的重塑是中枢神经系统（CNS） 奖赏底物，如核神经元（NAc），适应环境中不可预测的压力。 ECM是一种空间、分子和细胞上的异质结构，其影响神经活动、细胞-细胞 相互作用和血脑屏障完整性。然而，反复暴露于不可预测的压力会导致 ECM的分子和细胞重组，这影响了电路水平对压力引导的适应 神经活动和行为。ECM重塑部分由整合素控制：跨膜受体， 通过将ECM相关肽锚定到多种细胞类型来调节ECM。在细胞内，ECM包括 神经元过程以及星形胶质细胞的端足，星形胶质细胞是CNS驻留的神经胶质细胞。星形胶质细胞使 通过表达积极参与ECM重塑的多种整合素，在整个ECM中进行接触。 通过ECM内的这些密切相互作用，星形胶质细胞准备控制神经活动和行为。 然而，星形胶质细胞在对NAc ECM的反应中形成NAc ECM的机制和细胞-细胞相互作用， 不可预测的压力在很大程度上是未知的。在以前的研究工作中，我专注于描述 CNS中星形胶质细胞亚群对炎症的反应。我鉴定了b1整合素CD 29， 一种由整个中枢神经系统的星形胶质细胞表达的顶级标志物。CD 29参与多种复合物， 影响ECM组织的整合素。我以前的数据表明，CD 29+星形胶质细胞可能由以下组成： 通过与不同细胞相互作用在重塑ECM中发挥互补作用的异质亚群 类型然而，在体内快速研究星形胶质细胞亚群之间的相互作用一直是一个挑战。 为此，我最近开发了一种名为RABID-seq的新技术，可以描述星形胶质细胞与其他细胞的相互作用。 以高通量、全基因组规模和单细胞转录组学精度对细胞进行分析。因此，拉比德- seq是一种候选工具，用于定义ECM中CD 29+星形胶质细胞亚群响应于 不可预知的压力在这个建议中，我正在追求一个新的研究方向，以确定如何 暴露于不可预测的应力形状CD 29+星形胶质细胞的相互作用，定位和功能。我假设 定义的CD 29+星形胶质细胞亚群调节不同的ECM结构域，这些ECM结构域影响对 不可预知的压力我建议在以下具体目标中检验这一假设。在目标1中，我将定义 NAc内表达整合素的CD 29+星形胶质细胞亚群在急性和慢性反应中的相互作用 使用RABID-seq和CITE-seq的不可预测的应激。在目标2中，我将在空间上映射所占据的ECM域 通过空间转录组学和CD 29 cKO小鼠的每个CD 29 + NAc星形胶质细胞亚群，揭示CD 29 + 星形胶质细胞响应于应激重塑ECM。在目标3中，我将定义CD 29 + NAc星形胶质细胞如何调节 暴露于不可预测的压力后，在奖励寻求范式中小清蛋白+中间神经元的活性。 总之，我将研究应激如何影响NAc CD 29+星形胶质细胞的相互作用、位置和功能。

PROJECT SUMMARY/ABSTRACT Remodeling of the extracellular matrix (ECM) is a central mechanism by which central nervous system (CNS) reward substrates, such as the nucleus accumbens (NAc), adapt to unpredictable stressors in the environment. The ECM is a spatially, molecularly, and cellularly heterogeneous structure that impacts neural activity, cell-cell interactions, and blood-brain barrier integrity. However, exposure to repeated unpredictable stress leads to molecular and cellular reorganization of the ECM, which influences circuit-level adaptations to stress guiding neural activity and behavior. ECM remodeling is partially controlled by integrins: transmembrane receptors that regulate the ECM by anchoring ECM-associated peptides to multiple cell types. Cellularly, the ECM consists of neuronal processes and also the endfeet of astrocytes, which are CNS-resident glial cells. Astrocytes make contacts throughout the ECM by expressing multiple integrins that actively participate in ECM remodeling. Through these intimate interactions within the ECM, astrocytes are poised to control neural activity and behavior. However, the mechanisms and cell-cell interactions by which astrocytes shape the NAc ECM in response to unpredictable stress are largely unknown. In PREVIOUS RESEARCH EFFORTS I focused on characterizing the responses of astrocyte subsets in the CNS in response to inflammation. I identified the b1 integrin CD29 as a top marker expressed by astrocytes throughout the CNS. CD29 participates in multiple complexes with other integrins that affect ECM organization. My previous data suggest that CD29+ astrocytes might be composed of heterogeneous subsets that play complementary roles in remodeling the ECM by interacting with distinct cell types. However, it has been historically challenging to rapidly study the interactions of astrocyte subsets in vivo. To this end, I recently developed a new technique called RABID-seq that profiles astrocyte interactions with other cells at high throughput, on the genome-wide scale, and with single-cell transcriptomic precision. Thus, RABID- seq is a candidate tool to define the interactions of CD29+ astrocyte subsets in the ECM in response to unpredictable stress. In this proposal, I AM PURSUING A NEW RESEARCH DIRECTION to identify how exposure to unpredictable stress shapes CD29+ astrocyte interactions, localization, and function. I hypothesize that defined subsets of CD29+ astrocytes regulate distinct ECM domains that influence behavioral responses to unpredictable stress. I propose to test this hypothesis in the following Specific Aims. In Aim 1, I will define the interactions of integrin-expressing CD29+ astrocyte subsets within the NAc in response to acute and chronic unpredictable stress using RABID-seq and CITE-seq. In Aim 2, I will spatially map the ECM domains occupied by each subset of CD29+ NAc astrocytes via spatial transcriptomics and CD29 cKO mice to uncover how CD29+ astrocytes remodel the ECM in response to stress. In Aim 3, I will define how CD29+ NAc astrocytes regulate the activity of parvalbumin+ interneurons in a reward-seeking paradigm after exposure to unpredictable stress. IN SUMMARY, I will study how stress affects the interactions, location, and function of NAc CD29+ astrocytes.