Molecular pathways connecting NMDA receptors to the actin cytoskeleton

连接 NMDA 受体与肌动蛋白细胞骨架的分子途径

• 批准号: RGPIN-2018-06409
• 负责人: Ramsey, Amy
• 金额: $ 4.66万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762116
• 关键词: Molecular; pathways; connecting; NMDA; receptors

NMDA receptors (NMDARs) are a type of glutamate neurotransmitter receptor that is widely expressed in the central nervous system. They play a fundamental role in the process of synaptic plasticity. Synaptic plasticity refers to the process by which neurons change the strength and number of connections in the developing brain and throughout life. NMDARs are required for many forms of synaptic plasticity, and when NMDAR function is compromised, it impacts the patterns of connections that are made during development and impairs learning and memory. Interestingly, there is growing evidence that synaptic plasticity is accompanied by changes in the number and morphology of dendritic spines. Accordingly, NMDAR dysfunction leads to a loss of dendritic spines, although the molecular events that cause this have not been determined.In our laboratory, we have studied the impact of NMDAR dysfunction using pharmacological and genetic mouse models. Genetic NMDAR knockdown mice have reductions in cortical and striatal spine density, and have impaired learning and memory in several cognitive tasks. We have begun to elucidate the molecular changes that occur when NMDARs are dysfunctional, and have identified changes in the RhoGTPase signal transduction pathway. This pathway is known to regulate actin cytoskeleton dynamics, and changes in Rho signaling lead to changes in spine number and morphology. Therefore, we hypothesize that the impact of NMDAR dysfunction on RhoGTPase signaling is the cause of spine loss.The overall goal of this proposal is to elucidate the molecular machinery that connects NMDAR activity to the actin cytoskeleton to control spine shape and number. In the first aim, we will determine which components of the RhoGTPase pathways are affected by genetic or pharmacologic manipulation of NMDARs. This work will be performed in primary neuron cultures and in vivo. In the second aim of this proposal, we will manipulate the levels and activity of RhoGTPase effectors to determine whether this reverses spine deficits and cognitive impairments that are caused by NMDAR dysfunction.The proposed studies are a substantial part of our laboratory's ongoing research program, which is to understand the many ways that NMDA receptors regulate gene expression and neuron cell biology. We want to understand how specific cell types differ in the signal transduction cascades that are triggered by NMDA receptors, and how this ultimately affects synaptic function.

NMDA 受体（NMDAR）是一种广泛表达于中枢神经系统的谷氨酸神经递质受体。它们在突触可塑性过程中发挥着重要作用。突触可塑性是指神经元改变发育中的大脑和整个生命过程中连接的强度和数量的过程。 NMDAR 是多种形式的突触可塑性所必需的，当 NMDAR 功能受到损害时，它会影响发育过程中形成的连接模式，并损害学习和记忆。有趣的是，越来越多的证据表明突触可塑性伴随着树突棘数量和形态的变化。因此，NMDAR 功能障碍会导致树突棘丢失，尽管导致这种情况的分子事件尚未确定。在我们的实验室中，我们使用药理学和遗传小鼠模型研究了 NMDAR 功能障碍的影响。 NMDAR 基因敲除小鼠的皮质和纹状体棘密度降低，并且在多种认知任务中的学习和记忆能力受损。我们已经开始阐明 NMDAR 功能失调时发生的分子变化，并确定了 RhoGTPase 信号转导途径的变化。已知该通路可调节肌动蛋白细胞骨架动力学，Rho 信号传导的变化会导致脊柱数量和形态的变化。因此，我们假设 NMDAR 功能障碍对 RhoGTPase 信号传导的影响是脊柱丢失的原因。该提案的总体目标是阐明将 NMDAR 活性与肌动蛋白细胞骨架连接起来以控制脊柱形状和数量的分子机制。第一个目标是确定 RhoGTPase 通路的哪些成分受到 NMDAR 的遗传或药理学操作的影响。这项工作将在原代神经元培养物和体内进行。在本提案的第二个目标中，我们将操纵 RhoGTPase 效应器的水平和活性，以确定这是否可以逆转由 NMDAR 功能障碍引起的脊柱缺陷和认知障碍。拟议的研究是我们实验室正在进行的研究计划的重要组成部分，是了解 NMDA 受体调节基因表达和神经元细胞生物学的多种方式。我们想要了解特定细胞类型在 NMDA 受体触发的信号转导级联中有何不同，以及这最终如何影响突触功能。