The role of nitric oxide signaling in synaptic plasticity

一氧化氮信号传导在突触可塑性中的作用

• 批准号: RGPIN-2014-06085
• 负责人: Ryan, Scott
• 金额: $ 2.91万
• 依托单位: University of Guelph
• 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=688114
• 关键词: role; nitric; oxide; signaling; synaptic

Learning and memory has at its core modifications to tiny spine like structures that exist on a special subset of neurons in the brain known as "spiny neurons." These spines must move, adapt, grow and retract in response to chemical neurotransmitters in the brain, a process that as a whole is believed to be the cellular manifestation of learning, known as synaptic plasticity. The spines themselves are thought to serve as basic units of memory storage. While much work has focused directly on the chemical signals that mediate communication in the brain and the ion channels that are opened as a result, little is know of the specific signaling pathways that control the actual generation, shape and loss of individual spines. This proposal aims to shed light on this process by focusing on a specific molecule (Nitric Oxide) that is produced in these spines following ion channel opening. Nitric Oxide is unique in that it can directly alter the proteins responsible for dynamic changes to spine morphology. This proposal is driven by the hypothesis that Nitric Oxide signaling regulates synaptic plasticity by altering the density and morphology of spines through a process called S-nitrosylation.**Ion channels link a cell with the environment that surrounds it. These channels allow the cell to interpret its surroundings by responding to neurotransmitters and propagating signals from the environment outside of the cell inward. These signals mediate changes in the structure and shape of the cell itself and facilitate spine growth and retraction. One class of ion channel of interest to this proposal is characterized by its ability to respond to a neurotransmitter called glutamate. Glutamate signaling can increase the efficiency of communication between cells in the brain by both increasing the number and stability of new spines as well by pruning excess or unnecessary spines, leaving a more efficient communication network. Glutamate-mediated opening of the "NMDA" type ion channel results in production of Nitric Oxide that modifies the proteins in spines through a chemical reaction called S-Nitrosylation. This event alters the function of near-by proteins and as a result the dynamic properties of the spines they inhabit. While it is estimated that 50% of proteins in the brain are altered by S-nitrosylation, a comprehensive analysis of the role it plays in synaptic plasticity has never been performed.**Using powerful mouse genetics we will control the level of Nitric Oxide synthesized in spines by altering the genetic composition of the NMDA-type ion channel and thus its ability to open and close. Using live imaging microscopy techniques coupled with fluorescent probes, we will monitor the flux of ions through NMDA-type channels as well the amount Nitric Oxide subsequently produced in cultured brain slices and isolated neurons from these mice. This will allow us to determine how the level of Nitric Oxide correlates with dynamic changes to spine morphology. We will then monitor what proteins are S-nitrosylated by Nitric Oxide under conditions of spine growth, spine stabilization and spine retraction using Mass Spectrometry to analyze changes to proteins composition. This will form the basis of a novel molecular pathway that underlies the processes of synaptic plasticity. Moreover, this research program will further our understanding neural architecture and the means by which cells of the brain communicate.

学习和记忆的核心是对微小脊柱状结构的修改，这些结构存在于大脑中称为“棘神经元”的特殊神经元子集上。这些棘必须移动、适应、生长和收缩，以响应大脑中的化学神经递质，这一过程总体上被认为是学习的细胞表现，称为突触可塑性。脊柱本身被认为是记忆存储的基本单位。虽然许多工作直接集中在介导大脑通讯的化学信号以及由此打开的离子通道上，但人们对控制单个棘的实际生成、形状和损失的特定信号通路知之甚少。该提案旨在通过关注离子通道打开后这些棘中产生的特定分子（一氧化氮）来阐明这一过程。一氧化氮的独特之处在于它可以直接改变负责脊柱形态动态变化的蛋白质。 这一提议是基于这样的假设：一氧化氮信号传导通过一种称为 S-亚硝基化的过程改变树突棘的密度和形态来调节突触可塑性。**离子通道将细胞与其周围的环境连接起来。这些通道允许细胞通过响应神经递质并向内传播来自细胞外部环境的信号来解释其周围环境。这些信号介导细胞本身结构和形状的变化，并促进脊柱生长和收缩。该提议感兴趣的一类离子通道的特征是其能够响应称为谷氨酸的神经递质。谷氨酸信号传导可以通过增加新棘的数量和稳定性以及修剪多余或不必要的棘来提高大脑细胞之间的通信效率，从而留下更有效的通信网络。谷氨酸介导的“NMDA”型离子通道打开会导致一氧化氮的产生，一氧化氮通过称为 S-亚硝基化的化学反应来修饰刺中的蛋白质。这一事件改变了附近蛋白质的功能，从而改变了它们所居住的刺的动态特性。虽然据估计大脑中 50% 的蛋白质会因 S-亚硝基化而改变，但从未对其在突触可塑性中所起的作用进行全面分析。**利用强大的小鼠遗传学，我们将控制合成一氧化氮的水平通过改变 NMDA 型离子通道的遗传组成及其打开和关闭的能力来改变脊柱。使用实时成像显微镜技术与荧光探针相结合，我们将监测通过 NMDA 型通道的离子通量，以及随后在培养的脑切片和来自这些小鼠的分离神经元中产生的一氧化氮的量。这将使我们能够确定一氧化氮的水平如何与脊柱形态的动态变化相关。然后，我们将使用质谱法监测在脊柱生长、脊柱稳定和脊柱收缩的条件下，哪些蛋白质被一氧化氮 S-亚硝基化，以分析蛋白质组成的变化。这将构成突触可塑性过程的新型分子途径的基础。此外，该研究计划将进一步了解神经结构和大脑细胞通信的方式。