Define Interneuron Subpopulations in the Mouse Spinal Cord during Development

定义发育过程中小鼠脊髓的中间神经元亚群

• 批准号: RGPIN-2016-04880
• 负责人: Zhang, Ying
• 金额: $ 2.04万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=682215
• 关键词: Define; Interneuron; Subpopulations; Mouse; Spinal

Precise organization of neural circuits ensures proper functioning of the central nervous system (CNS). Assembly of these circuits requires correct specification of neuronal populations defined during development. One goal in my research is to understand developmental processes underlying formation of functional groups of spinal neurons. Different progenitor domains in the embryonic spinal cord give rise to the motoneurons (MNs) and different interneuron (IN) classes, each with a unique molecular profile. Distinct types of spinal INs emerge from these progenitor domains, and, as recently revealed, some undergo further subdivision to form heterogeneous populations. As yet, however, little is known about molecular mechanisms that govern such subdivision. *** My lab focuses on an IN group known as V3s as a model system to study subdivision of spinal INs during development. V3 INs arise from a ventral progenitor domain, p3, and express the Sim1 transcription factor at early postmitotic stages. V3 INs are glutamatergic and commissural. In mice, genetic deletion of the entire V3 population prevents animals from exhibiting robust and stable gait. We recently demonstrated that at least two V3 subpopulations, ventral and dorsal, reside in mature spinal cord, each with distinct physiological and anatomical properties. Nevertheless, molecular markers required to define these subpopulations and their function remain unavailable. Moreover, our most recent studies, supported by NSERC funding, suggest that differing physiological properties displayed by V3 subpopulations are present embryonically and that Sim1 may play different roles in regulating their establishment. Therefore, we propose to define molecular markers of V3 subpopulations and mechanisms underlying Sim1 function during development. To do so, we will use transgenic mice to trace V3 INs in wild-type control and Sim1-deficient mice during embryogenesis. We will combine electrophysiology, immunohistochemistry, in situ hybridization and microarray/RNA sequencing screening to conduct the following studies:***Aim I. Define physiological V3 subpopulations at embryonic stages to establish a timeline showing when V3 subpopulations start to display distinctive physiological properties. ****Aim II. Identify specific molecular markers, especially specific transcription factors, of V3 subpopulations to define molecular profiles for different V3 subpopulations. ***Aim III. Investigate molecular pathways that regulate the V3 subpopulation formation by Sim1 to determine which downstream molecular factors are regulated by the Sim1 transcription factor during embryonic development. *** Successful completion of these studies will allow us to distinguish V3 subpopulations and determine their function in spinal circuits. Our work could also pave the way for studies designed to assess formation of other IN subpopulations. **

神经回路的精确组织确保中枢神经系统 (CNS) 的正常运作。这些电路的组装需要在开发过程中定义的神经元群体的正确规范。 我的研究目标之一是了解脊髓神经元功能群形成的发育过程。胚胎脊髓中的不同祖细胞结构域产生运动神经元 (MN) 和不同的中间神经元 (IN) 类别，每种类别都具有独特的分子特征。不同类型的脊髓 IN 从这些祖细胞域中出现，并且正如最近所揭示的那样，其中一些经过进一步细分以形成异质群体。然而，迄今为止，人们对控制这种细分的分子机制知之甚少。 *** 我的实验室专注于称为 V3 的 IN 组，作为模型系统来研究发育过程中脊髓 IN 的细分。 V3 IN 源自腹侧祖细胞结构域 p3，并在有丝分裂早期阶段表达 Sim1 转录因子。 V3 IN 具有谷氨酸能和连合性。 在小鼠中，整个 V3 群体的基因缺失会阻止动物表现出稳健而稳定的步态。我们最近证明，至少有两个 V3 亚群（腹侧和背侧）存在于成熟的脊髓中，每个亚群都具有不同的生理和解剖特性。 然而，定义这些亚群及其功能所需的分子标记仍然无法获得。此外，我们最近在 NSERC 资助下的研究表明，V3 亚群表现出的不同生理特性在胚胎时期就存在，并且 Sim1 可能在调节其建立过程中发挥不同的作用。 因此，我们建议在开发过程中定义 V3 亚群的分子标记和 Sim1 功能的潜在机制。为此，我们将使用转基因小鼠在胚胎发生过程中追踪野生型对照小鼠和 Sim1 缺陷小鼠中的 V3 IN。我们将结合电生理学、免疫组织化学、原位杂交和微阵列/​​RNA测序筛选来进行以下研究：***目标I.定义胚胎阶段的生理V3亚群，以建立显示V3亚群何时开始表现出独特生理特性的时间线。 ****目标二。识别 V3 亚群的特定分子标记，尤其是特定转录因子，以定义不同 V3 亚群的分子谱。 ***目标三。研究 Sim1 调节 V3 亚群形成的分子途径，以确定胚胎发育过程中哪些下游分子因子受到 Sim1 转录因子的调节。 *** 成功完成这些研究将使我们能够区分 V3 亚群并确定它们在脊髓回路中的功能。我们的工作还可以为旨在评估其他 IN 亚群形成的研究铺平道路。 **