Mechanisms Underlying Neural Stem Cell Heterogeneity in the Adult Hippocampus

描述（由申请人提供）：成体神经干细胞（NSCs）有助于大脑可塑性和维持组织稳态。了解NSCs如何重塑成人海马体可能为神经适应性和修复提供关键见解。NSC功能的定义是在产生神经元和胶质子代的同时维持前体状态的能力。最近，我开发了一种新的体内克隆分析系统，以揭示成年哺乳动物海马体中单细胞水平的干细胞特性，海马体是学习和记忆的关键区域。我们之前的研究表明，放射状胶质样细胞（RGL）可以作为干细胞，但在增殖、产生后代和自我更新方面表现出显著的异质性。剩下的一个基本问题是，这些差异背后的机制是什么。笔者推测，RGL行为的差异是由于它们的增殖状态和对环境变化（包括GABA信号和中风损伤）的反应不同所致。为了解决这些问题，我建立了独立的模型系统，优先针对静止和有丝分裂的rgl。我将首先通过进行体内单细胞谱系追踪来描述这些内在偏见的RGL亚群中的NSC潜力。在建立了这个基础之后，我们将评估GABA信号如何作为一种外部分子机制，在生理条件下调节静止和活跃的RGLs中的干细胞决策。最后，我们将确定中风损伤如何在病理条件下决定RGL细胞的命运和静止和活跃亚群的潜力。重要的是，在受指导阶段学习的基于病毒的基因传递、光遗传学和中风手术技能是研究独立阶段外部生态位调控的多学科方法的重要组成部分。总的来说，本研究旨在了解NSC在本质上不同的rgl中的行为，以及它们的决定如何与特定的生理和病理机制相互作用。

DESCRIPTION (provided by applicant): Adult neural stem cells (NSCs) contribute to brain plasticity and maintain tissue homeostasis. Understanding how NSCs remodel the adult hippocampus may provide key insight into neural adaptability and repair. NSC function is defined by the ability to maintain a precursor state while generating neuronal and glial progeny. Recently, I developed a new in vivo clonal analysis system to reveal stem cell properties at the single cell level within the adult mammalian hippocampus, an area critical for learning and memory. We previously showed that radial glia-like (RGL) cells can act as stem cells, but exhibit significant heterogeneity in their decisions to proliferate, generate progeny and self-renew. A fundamental remaining question is what mechanisms underlie these differences. I hypothesize that divergent RGL behavior results from differences in their proliferative state and responses to changes in environment including GABA signaling and stroke injury. To address these points, I have established independent model systems that preferentially target quiescent and mitotic RGLs. I will first characterize NSC potential within these intrinsically biased RGL subpopulations by performing in vivo single cell lineage tracing. After establishing this foundation, we will assess how GABA signaling acts as an extrinsic molecular mechanism to regulate stem cell decisions in quiescent and active RGLs under physiological condition. Finally, we will determine how stroke injury dictates RGL cell fate decisions and potential in quiescent and active subpopulations under pathological conditions. Importantly, viral-based gene delivery, optogenetics and stroke surgery skills learned during the mentored phase are essential components toward a multidisciplinary approach for investigating extrinsic niche regulation during the independent phase. Collectively, this research seeks to understand NSC behavior in intrinsically different RGLs and how their decisions interact with specific physiological and pathological mechanisms.