Examining the role of specific NMDA receptor subunits in cortical circuit dysfunction in Fragile X Syndrome

检查特定 NMDA 受体亚基在脆性 X 综合征皮质回路功能障碍中的作用

基本信息

批准号：
10749864
负责人：
Aleya Michelle Shedd
金额：
$ 3.84万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
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：
2023-09-01 至 2026-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10749864
关键词：
Acute Affect Astrocytes Auditory Biological Markers Brain Cells Collaborations Complement Cortical Synchronization Data Development Electroencephalography Etiology FMR1 Fragile X Syndrome Functional disorder Genetic Markers Genetic Transcription Goals Human Hypersensitivity Impaired cognition Individual Inherited Intellectual functioning disability Interneurons Intervention Knock-out Knockout Mice Knowledge Measurement Measures Mediating Messenger RNA Molecular Mus N-Methyl-D-Aspartate Receptors N-Methylaspartate Neocortex Neurons Neurotransmitter Receptor Parvalbumins Phase Phenotype Predisposition Process Proteins Quantitative Reverse Transcriptase PCR Regulation Reporting Research Rest Role Seizures Sensory Slice Social Behavior Somatosensory Cortex Stimulus Synapses Testing Tuberous Sclerosis Up-Regulation Western Blotting audiogenic seizure autism spectrum disorder awake cell cortex cell type common symptom confocal imaging design excitatory neuron experimental study frontal lobe in vivo inhibitory neuron insight mouse model multi-electrode arrays neocortical network dysfunction new therapeutic target novel therapeutics patch clamp pharmacologic protein expression response sensory cortex sensory mechanism sensory stimulus targeted treatment therapeutic development therapeutic target

项目摘要

PROJECT SUMMARY Sensory hypersensitivity is a common symptom in autism and Fragile X Syndrome (FXS) and is thought to be a result of cortical circuit dysregulation. EEG studies in humans with FXS and the FXS mouse model, the Fmr1 KO, reveal cortical circuit hyperexcitability and synchrony deficits such as enhanced resting state power in the gamma band and reduced sensory-driven synchrony. In acute slices, this hyperexcitability can be observed as prolonged persistent activity states, called UP states, and increased gamma band power during UP states. I hypothesize that circuit mechanisms that mediate hyperexcitability and prolonged UP states in the neocortex may contribute to EEG phenotypes in FXS. Using positive and negative allosteric modulators (PAMs/NAMs) specific for GluN2C/D subunits of NMDA receptors, I have revealed an upregulation of GluN2C/D function in the Fmr1 KO cortex that contributes to circuit hyperexcitability. Specifically, GluN2C/D PAMs increase UP state duration and gamma power during the UP states, while NAMs rescue UP state duration. Remarkably, these interventions only affected the Fmr1 KO, not their wildtype (WT) littermates suggesting that GluN2C/D function is upregulated in the Fmr1 KO and leads to cortical circuit dysfunction. Typically, GluN2C/D subunits are expressed in cortical inhibitory neurons and astrocytes. Since my results are not consistent with effects on inhibitory neurons, GluN2C/D subunits may be misexpressed in excitatory neurons or upregulated in astrocytes in the Fmr1 KO. I hypothesize that GluN2C/D expression and/or function is increased in excitatory neurons and/or astrocytes in Fmr1 KO mice and this contributes to hyperexcitability and altered synchrony of cortical circuits. The goal of the proposed project is to test this hypothesis and determine expressional and functional changes in Glun2C/D that may contribute to cortical hyperexcitability and synchrony following three Specific Aims. Aim 1. To determine change in cortical protein and RNA expression levels as well as cell specific expression of GluN2C/D subunits in Fmr1 KO cortex. Aim 2. To determine cell specific functional contribution of GluN2C/D subunits to NMDA-mediated currents in WT and Fmr1 KO cortex. Aim 3. To determine the contribution of GluN2C/D NMDARs to in vivo sensory driven circuit excitability and altered synchrony using multi-electrode array EEG and measurement of audiogenic seizures in the Fmr1 KO mouse in collaboration with Dr. Devin Binder at UC Riverside. These experiments will not only provide insights into the molecular and cellular basis of GluN2C/D contribution to cortical circuit dysfunction, but also examine GluN2C/D subunits as a potential target for therapeutic development using translational biomarkers.

项目概要感觉过敏是自闭症和脆性 X 综合征 (FXS) 的常见症状，被认为是一种皮质回路失调的结果。使用 FXS 和 FXS 小鼠模型 Fmr1 对人类进行脑电图研究 KO，揭示皮层回路过度兴奋性和同步性缺陷，例如增强静息态能力伽玛波段和减少的感觉驱动同步。在急性切片中，这种过度兴奋可以观察为延长持续活动状态（称为 UP 状态），并在 UP 状态期间增加伽马能带功率。我假设介导新皮质过度兴奋和延长 UP 状态的电路机制可能有助于 FXS 的脑电图表型。使用正负变构调节剂 (PAM/NAM) 特异性针对 NMDA 受体的 GluN2C/D 亚基，我发现 GluN2C/D 功能上调 Fmr1 KO 皮层有助于电路过度兴奋。具体来说，GluN2C/D PAM 会增加 UP 状态 UP 状态期间的持续时间和伽马功率，而 NAM 则挽救 UP 状态持续时间。值得注意的是，这些干预措施仅影响 Fmr1 KO，而不影响其野生型 (WT) 同窝小鼠，表明 GluN2C/D 功能 Fmr1 KO 中上调并导致皮质回路功能障碍。通常，GluN2C/D 亚基是在皮质抑制性神经元和星形胶质细胞中表达。由于我的结果与效果不一致抑制性神经元中，GluN2C/D 亚基可能在兴奋性神经元中错误表达或在星形胶质细胞中上调在Fmr1 KO中。我假设 GluN2C/D 表达和/或功能在兴奋性状态下增加 Fmr1 KO 小鼠的神经元和/或星形胶质细胞，这会导致过度兴奋并改变皮质回路的同步。拟议项目的目标是检验这一假设并确定 Glun2C/D 的表达和功能变化可能导致皮质过度兴奋和同步以下三个具体目标。目标 1. 确定皮质蛋白和 RNA 表达水平的变化作为 Fmr1 KO 皮质中 GluN2C/D 亚基的细胞特异性表达。目标 2. 确定细胞特异性功能 GluN2C/D 亚基对 WT 和 Fmr1 KO 皮质中 NMDA 介导的电流的贡献。目标 3. 确定 GluN2C/D NMDAR 对体内感觉驱动电路兴奋性和改变同步性的贡献与 Fmr1 KO 小鼠合作进行多电极阵列脑电图和听源性癫痫发作测量加州大学河滨分校的 Devin Binder 博士。这些实验不仅将提供对分子和细胞的见解 GluN2C/D 对皮质回路功能障碍的贡献的基础，但也将 GluN2C/D 亚基作为潜在的使用转化生物标志物进行治疗开发的目标。