CRCNS US-German Research Proposal: Quantitative and Computational Dissection of Glutamatergic Crosstalk at Tripartite Synapses

CRCNS 美德研究提案：三方突触谷氨酸能串扰的定量和计算剖析

基本信息

批准号：
10612169
负责人：
Ghanim Ullah
金额：
$ 12.58万
依托单位：
UNIVERSITY OF SOUTH FLORIDA
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-02-15 至 2027-01-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10612169
关键词：
Affect Astrocytes Bioenergetics Brain Brain region Cell physiology Cells Cellular Morphology Chemical Synapse Communication Computer Models Data Development Disease Dissection Electrophysiology (science)Event Excitatory Synapse Extracellular Space Feedback Florida Fluorescence Microscopy Future German population Germany Giant Cells Glutamate Transporter Glutamates Heterogeneity Hippocampus Homeostasis Impairment Individual Ion Transport Ischemic Stroke Link Measures Modeling Molecular Monitor Morphology Mus N-Methyl-D-Aspartate Receptors Neocortex Neuronal Plasticity Neurons Pathway interactions Pharmacology Play Preparation Process Production Property Protons Research Research Proposals Role Side Signal Transduction Site Specificity Structure Synapses Synaptic Cleft Synaptic Transmission Techniques Testing Time Tissues Universities Viral Work density design driving force excitotoxicity experimental study extracellular fluorescence imaging fluorescence lifetime imaging image processing insight multi-scale modeling multiphoton imaging neocortical nervous system disorder neuronal cell body neuronal excitability neurotransmission novel novel strategies pharmacologic postsynaptic predictive modeling presynaptic spatiotemporal stoichiometry synaptic function tool transmission process uptake

项目摘要

CRCNS US-German Research Proposal: Quantitative and computational dissection of glutamatergic crosstalk at tripartite synapses (1) Christine R Rose, Heinrich Heine University, Düsseldorf, Germany (2) Christian Henneberger, University of Bonn, Germany (3) Ghanim Ullah, University of South Florida, Tampa, FL, USA Project Description 1 Introduction and Background Transmission at chemical synapses is the central mechanism by which information is transferred between neurons. Synaptic connections such as glutamatergic excitatory synapses are often perceived and modeled as point-to-point connections. However, there is substantial evidence that crosstalk between various glutamatergic synapses can occur when the presynaptically released glutamate is sensed not only by its direct postsynaptic partner but also by nearby synapses of the same and other neurons [4]. Notably, this phenomenon termed “glutamate spillover” not only defines the input-specificity of a given synaptic connection and its crosstalk to neighboring synapses, but is also involved in and controlled by activity-dependent plasticity [1, 7, 8]. How easily glutamate escapes from its release site and how far it spreads into the tissue depends on the morphological and molecular properties of the extracellular space (ECS) as well as on the efficacy of glutamate clearance, which primarily depends on astrocytic uptake [11, 12]. We and others have shown that the efficacy of perisynaptic glutamate uptake by astrocytes displays a remarkable heterogeneity between brain regions and, importantly, can vary drastically from one synapse to the next within a brain region [3, 7, 8]. This is in part because the morphological coverage of synapses by perisynaptic astrocyte processes (PAPs) can differ strongly between individual synapses [14]. Moreover, the Henneberger lab has recently shown that higher synaptic coverage by PAPs correlates with a higher local efficacy of glutamate uptake [3]. We have also demonstrated that in addition to being heterogeneous, astrocytic glutamate uptake and PAPs morphology both are controlled by neuronal plasticity [1]. Moreover, glutamate uptake is governed by the transporters’ stoichiometry, importing one glutamate molecule into the astrocyte by using the energy gained from co-transporting three Na+ and one proton down the electrochemical gradients, whilst also exporting one K+ [12]. While the inwardly-directed Na+ gradient is the main driving force for glutamate uptake, recent work by Rose lab and others have shown that glutamatergic activity causes local or global Na+ transients in astrocytes ([Na+]A) [15]. In the mouse hippocampus, astrocytic Na+ signals in fact arise predominately due to the activity of glutamate transporters themselves, degrading the Na+ gradient and thereby transiently weakening uptake capacity in a negative feedback-loop [15-17]. In the neocortex, glutamatergic synaptic activity in addition results in prominent Na+ influx through NMDA receptors, boosting astrocyte Na+ gradients [18]. Thus, it is increasingly appreciated that astrocytic glutamate uptake is neither static nor uniform. First, it is functionally dependent on the gradients of the transported ions which dynamically change with synaptic transmission [12]. Second, it is plastic because structural remodeling of PAPs on time scales of minutes profoundly alters perisynaptic glutamate spread [1]. Therefore, the emerging hypothesis is that the degree of glutamate spillover and, therefore, synaptic crosstalk in most brain regions are dynamically regulated and controlled at the level of the astrocytes. Furthermore, since a single astrocyte can contact thousands of synapses of various neurons, it has the potential to locally control the crosstalk of many synapses. In such a scenario, an astrocyte, or a subcellular domain of it, can coordinate crosstalk between many glutamatergic synapses on different neurons. Thereby, astrocytes and their PAPs set the spatial fidelity of glutamatergic synaptic transmission and as a consequence profoundly control neuronal signal exchange. So far, these important hypotheses remain largely untested. We will fill this gap by combining quantitative fluorescence imaging, astrocytic manipulations, and predictive computer modelling. This will be accomplished by investigating perisynaptic astrocytic Na+ gradients, the main driving force of glutamate uptake, and local mechanisms controlling them 1

CRCNS美国 - 德国研究建议：定量和计算解剖三方突触的谷氨酸能串扰（1）德国杜塞尔多夫的克里斯汀·罗斯，海因里希海恩大学（2）德国波恩大学克里斯蒂安·亨内伯格（Christian Henneberger）（3）加尼姆·乌拉（Ghanim Ullah），南佛罗里达大学，美国佛罗里达州坦帕市项目描述 1介绍和背景化学突触的传输是信息的中心机制转移在神经元之间。突触连接，例如谷氨酸能激发突触通常被视为并建模为点对点连接。但是，有大量证据表明，当各种谷氨酸盐突触之间的串扰可能发生突触前释放的谷氨酸不仅被其直接的突触后伴侣感知而且还通过附近的同一神经元的突触[4]。值得注意的是，这种现象被称为“谷氨酸Spilover”不仅定义了给定突触的输入特异性连接及其串扰与相邻的突触，但也参与并控制活动依赖性可塑性[1，7，8]。谷氨酸从其释放位点逃脱的容易程度以及它扩散到组织的范围取决于细胞外空间（EC）的形态和分子特性以及谷氨酸清除的效率，主要取决于星形胶质细胞的吸收 [11，12]。我们和其他星形胶质细胞显示大脑区域之间的显着异质性，重要的是从一个大脑区域内的一个突触到下一个[3、7、8]截然不同。这部分是因为围肌突触星形胶质细胞过程（PAPS）对突触的形态学覆盖率（PAPS）单个突触之间可以有很大的不同[14]。而且，Henneberger实验室有最近表明，PAPS较高的突触覆盖范围与较高的局部效率相关谷氨酸摄取[3]。我们还证明，除了异质外，星形细胞谷氨酸摄取和PAPS形态均由神经元可塑性控制 [1]。此外，谷氨酸摄取受运输者的化学计量测定，进口一个通过使用三个共同运动获得的能量，谷氨酸分子进入星形胶质细胞 Na+和一个质子向下电化学梯度，同时还导出一个K+ [12]。虽然向内指导的Na+梯度是谷氨酸吸收的主要驱动力，但最近 Rose Lab和其他人的工作表明，谷氨酸能活动会导致本地或全局NA+ 星形胶质细胞中的瞬态（[Na+] a）[15]。在小鼠海马中，星形细胞Na+信号实际上主要是由于谷氨酸转运蛋白本身的活性而出现的 NA+梯度，从而在负反馈环中暂时削弱吸收能力 [15-17]。在新皮层中，谷氨酸能突触活性以及显着的Na+ 通过NMDA受体涌入，增强星形胶质细胞Na+梯度[18]。这是越来越多的理解的是，星形胶质细胞谷氨酸摄取既不是静态的也不是制服。首先，它在功能上取决于运输离子的梯度通过突触传递动态变化[12]。其次，它是塑料的，因为结构按时间尺度的时间尺度重塑PAPS，深刻改变了凝血谷氨酸的蔓延 [1]。因此，新出现的假设是谷氨酸尖毛的程度和因此，大多数大脑区域的突触串扰受到动态调节和控制星形胶质细胞的水平。此外，由于单个星形胶质细胞可以联系数千个各种神经元的突触，它具有局部控制许多串扰的潜力突触。在这种情况下不同神经元上许多谷氨酸能突触之间的串扰。因此，星形胶质细胞他们的pap设定了谷氨酸能突触传播的空间保真度结果深刻控制神经元信号交换。到目前为止，这些重要的假设在很大程度上未经测试。我们将通过结合定量荧光成像，星形细胞操作和预测性计算机建模。这将通过研究直发星形胶质细胞Na+来实现梯度，谷氨酸吸收的主要驱动力以及控制它们的局部机制 1