Molecular Logic Sculpting Cell-Specific Contributions of Neurexin-1 at the Tripartite Synapse

分子逻辑塑造 Neurexin-1 对三联突触的细胞特异性贡献

• 批准号: 10594568
• 负责人: Justin Howard Trotter
• 金额: $ 15.17万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10594568
• 关键词: 3-Dimensional; AMPA Receptors; Address; Adult; Affect; Alternative Splicing; Astrocytes; Behavioral; Binding Proteins; Biological Assay; Brain; Brain Diseases; Brain region; Calcium; Cell Adhesion Molecules; Cells; Communication; Communications Media; Copy Number Polymorphism; Coupled; Coupling; Data; Dendritic Spines; Development; Disease; Dyes; Electrophysiology (science); Ensure; Etiology; Excitatory Synapse; Fluorescence Resonance Energy Transfer; Gap Junctions; Genes; Genetic; Gilles de la Tourette syndrome; Glutamate Transporter; Glutamates; Goals; Grant; Heparitin Sulfate; Hippocampus; Impairment; Knockout Mice; Knowledge; Ligand Binding; Ligands; Link; Logic; Measures; Mediating; Membrane; Mentors; Messenger RNA; Modification; Molecular; Morphology; Mus; Neurodevelopmental Disorder; Neuroglia; Neurons; Physiological; Postsynaptic Membrane; Potassium Channel; Potassium Glutamate; Prevalence; Probability; Property; Protein Isoforms; Proteins; Regulation; Research; Role; Schizophrenia; Short-Term Memory; Signal Transduction; Synapses; Synaptic Transmission; Testing; Training; Variant; academic preparation; autism spectrum disorder; biocytin; career; conditional knockout; density; design; differential expression; experimental study; hippocampal pyramidal neuron; improved; insight; long term memory; mutant; new therapeutic target; novel; novel therapeutics; patch clamp; postsynaptic; postsynaptic neurons; preference; presynaptic; programs; receptor function; response; spatial memory; synaptic function; transmission process; two photon microscopy

ABSTRACT Substantial evidence implicates copy number variations (CNVs) of the gene encoding Neurexin-1 (Nrxn1), a synaptic cell adhesion molecule, in the pathoetiology of Autism spectrum disorder, schizophrenia, and Tourette syndrome. However, very little is known regarding the function and regulation of Nrxn1 at developing and adult synapses, an understanding of which may improve our knowledge of brain disorders and reveal novel therapeutic targets. My preliminary data show that Nrxn1 is not only expressed by neurons, but also by astrocytes, challenging the classical view of Nrxn1 as being exclusively presynaptic. Here, I propose that astrocytic Nrxn1 mediates an important form of communication between astrocytes and synapses that is required for normal excitatory synapse development and function. My preliminary findings show that astrocytic and neuronal Nrxn1 fundamentally differ in major isoform expression, alternative splicing, and heparan sulfate (HS) modification. Selective loss of astrocytic Nrxn1 leads to a significant and selective reduction in AMPA receptor (AMPAR)- mediated synaptic transmission without affecting synapse number in the hippocampus, a brain region important for consolidation of information from short-term memory to long-term memory and spatial memory. How does the postsynaptic membrane, which contains numerous neurexin ligands (e.g. LRRTMs, neuroligins, etc.), distinguish between presynaptic and astrocytic Nrxn1 to allow compartment-specific signaling within the tripartite synapse? In order to better understand the molecular mechanisms utilized by astrocytic Nrxn1 to instruct synapse development I will perform rescue experiments in Nrxn1 astrocyte conditional knockout (acKO) mice using AAVs to deliver Nrxn1 variants differing in major isoform identity, alternative splicing, HS modification, and intracellular signaling. Recordings of both spontaneous and evoked excitatory synaptic responses will be performed on CA1 pyramidal neurons to measure rescue efficacy. Next, I will extend our understanding of the functional consequences of Nrxn1 deletion through studying whether astrocytic Nrxn1 is required for basal and/or activity-induced changes in dendritic spine morphology and density, as well as the three-dimensional density of functional AMPARs. Finally, the synaptic deficits observed following deletion of astrocytic Nrxn1 may be a downstream consequence of impaired astrocyte function. Thus, I will measure several aspects of astrocyte function following Nrxn1 deletion in astrocytes, including physiological (i.e. membrane properties and channel currents), morphological (i.e. territory, gap-junction coupling, and association with synapses), and circuit-related (i.e. calcium dynamics) properties. It is anticipated that the proposed research will provide critical insights into the molecular and cellular basis of how Nrxn1 CNVs give rise to neurodevelopmental disorders and will shed light on a novel molecular program underpinning communication between neuronal and astrocytic compartments of the tripartite synapse.

抽象的 大量证据暗示了编码神经1（NRXN1）的基因的拷贝数变化（CNV），A 突触细胞粘附分子，在自闭症谱系障碍，精神分裂症和图片的病原学中 综合征。但是，关于NRXN1在发展中和成人的功能和调节方面知之甚少 突触，对此的理解可能会改善我们对脑部疾病的了解并揭示新的治疗性 目标。我的初步数据表明，NRXN1不仅由神经元表达，而且由星形胶质细胞表达， 挑战NRXN1的经典观点是独家突触前的。在这里，我提出了星形胶质细胞NRXN1 介导正常所需的星形胶质细胞和突触之间的一种重要形式 兴奋性突触的发展和功能。我的初步发现表明星形细胞和神经元NRXN1 主要同工型表达，替代剪接和硫酸乙酰肝素（HS）修饰的根本上有所不同。 星形胶质细胞NRXN1的选择性丧失会导致AMPA受体（AMPAR）的显着降低 - 介导的突触传播而不会影响海马的突触数，这是大脑区域重要的 为了整合从短期记忆到长期记忆和空间内存的信息。怎么样 突触后膜中包含许多神经毒素配体（例如LRRTMS，Neuroligins等）， 区分突触前和星形细胞NRXN1以允许三方内的隔室特异性信号传导 突触？为了更好地了解星形胶质细胞NRXN1使用的分子机制 突触开发I将在NRXN1星形胶质细胞有条件敲除（ACKO）小鼠中进行救援实验 使用AAV传递主要同工型身份，替代剪接，HS修改和 细胞内信号传导。自发和诱发兴奋性突触反应的记录将是 在CA1锥体神经元上进行救援功效。接下来，我将扩展我们对 NRXN1缺失的功能后果通过研究是否需要星形胶质细胞NRXN1和/或 活动引起的树突状脊柱形态和密度的变化以及三维密度 功能性AMPAR。最后，在删除星形细胞NRXN1后观察到的突触缺陷可能是 星形胶质细胞功能受损的下游结果。因此，我将测量星形胶质细胞的几个方面 星形胶质细胞中NRXN1缺失后的功能，包括生理学（即膜特性和通道 电流），形态学（即区域，间隙 - 结耦合以及与突触的关联）和与电路有关的 （即钙动力学）性质。预计拟议的研究将为您提供关键见解 NRXN1 CNV如何产生神经发育障碍的分子和细胞基础，并将脱落 关于神经元和星形胶质细胞隔室之间通信的新分子程序的光明 三方突触。