Molecular Mechanisms Regulating Inhibitory Circuitry in the Spinal Cord

调节脊髓抑制电路的分子机制

• 批准号: 10159975
• 负责人: Julia Anna Kaltschmidt
• 金额: $ 36.36万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10159975
• 关键词: Adhesions; Adhesives; Afferent Neurons; Anatomy; Animal Behavior; Attenuated; Axon; Binding; Biological Assay; Cell Adhesion; Cell Adhesion Molecules; Cholera Toxin Protomer B; Coupled; Development; Disease; Distal; Dyes; Electrophysiology (science); Extensor; Flexor; Foundations; Functional disorder; Generations; Goals; Health; In Vitro; Individual; Injections; Injury; Interneurons; Knowledge; Label; Limb structure; Measures; Mediating; Medical; Methodology; Mission; Molecular; Motor; Motor Neurons; Mus; Muscle; Muscle function; Neuraxis; Neurodegenerative Disorders; Neurologic; Neurons; Neurotrophin 3; Phenotype; Physiological; Process; Proprioceptor; Proteins; Public Health; Reporter; Research; Role; Schizophrenia; Science; Sensory; Signal Transduction; Specificity; Spinal; Spinal Cord; Spinal cord injury; Synapses; Tamoxifen; Testing; Tracer; United States National Institutes of Health; Work; contactin; density; differential expression; effective therapy; experimental study; fluorophore; improved; in vivo; innovation; knowledge base; mouse genetics; nervous system disorder; neural circuit; neuronal circuitry; neuropsychiatry; neurotransmitter release; presynaptic; protein complex; receptor; relating to nervous system; sensory input; synaptogenesis; targeted treatment

Establishing specific neuronal circuits is fundamental for the generation of coordinated muscle function. However, the signals underlying the specificity of connection between interneurons and their targets in the mammalian central nervous system (CNS) remain largely unknown to date. Our long-term research goal is to understand the rules of interneuron circuit wiring and the molecular mechanisms that control it. The objective of the proposed research is to describe how a combination of adhesive and neurotrophic signals determine GABAergic interneuron circuit connectivity. A class of GABAergic interneurons, termed GABApre, forms synaptic contacts with the terminals of proprioceptive sensory afferents, and thus directly controls proprioceptive sensory input through an inhibitory strategy known as presynaptic inhibition. We will test the hypothesis that the connectivity of a class of spinal GABAergic neurons varies between functionally-distinct sensory neurons and that this connectivity is mediated via (ii) differential expression of muscle-derived neurotrophin (NT)-3 and (ii) a matrix of IgSF adhesion proteins. The rationale underlying this proposal is that through understanding the mechanisms underlying GABAergic interneuron circuit formation, we will enhance our understanding of — and ultimately control over — inhibitory neuronal circuit development and function in vivo. We will test our hypothesis with the following three aims: #1) Determine the functional specificity of GABAergic interneuron circuitry; #2) Investigate the influence of muscle-derived NT-3 on GABApre synapse formation; and #3) Assess the role of Contactin-5 in GABApre-sensory synapse formation. In the first aim, we combine timed tamoxifen injections, mouse genetics and CTb labeling to analyze whether the specific connectivity of individual GABApre interneurons may be functionally relevant. In the second aim, we examine the expression of Gabrg1 in functionally distinct proprioceptive sensory neurons and assess consequences of changing NT-3 levels on both Gabrg1 expression and GABApre terminal number. In the third aim, we perturb cell adhesion signaling using mouse genetics and perform phenotypic analysis using molecular, micro-anatomic and functional assays, including an electrophysiological measure of presynaptic inhibition. We also use an in vitro binding assay to screen for new adhesion molecule candidates relevant for GABApre synaptic specificity in vivo. The research proposed in this application is innovative because it combines a molecularly-defined interneuronal circuit with a unique constellation of methodologies to integrate functional specificity with target-derived signals. The research will provide an understanding of functional diverse GABApre circuitry and also advance our understanding of how basic circuit paradigms may be adapted for diverse motor functions. The proposed work is significant because it will contribute to fundamental knowledge of the formation of circuit-level mechanisms and neural strategies used in the CNS; this in turn will advance our efforts to develop effective therapies to rebuild circuitry and muscle function after spinal cord injury or other neurological diseases.

建立特定的神经元回路是产生协调的肌肉功能的基础。 然而，中间神经元与其目标之间的连接特异性背后的信号 迄今为止，哺乳动物中枢神经系统（CNS）仍然很大程度上未知。我们的长期研究目标是 了解中间神经元电路布线的规则以及控制它的分子机制。的目标 拟议的研究旨在描述粘附信号和神经营养信号的组合如何决定 GABA能中间神经元电路连接。一类 GABA 能中间神经元，称为 GABApre，形成突触 与本体感觉传入的末端接触，从而直接控制本体感觉 通过称为突触前抑制的抑制策略进行输入。我们将检验以下假设： 一类脊髓 GABA 能神经元的连接在功能不同的感觉神经元和 这种连接是通过 (ii) 肌肉源性神经营养素 (NT)-3 的差异表达和 (ii) IgSF 粘附蛋白基质。该提案的基本原理是，通过了解 GABAergic 中间神经元回路形成的机制，我们将增强我们对 - 和 最终控制——体内抑制性神经元回路的发育和功能。我们将检验我们的假设 具有以下三个目标：#1）确定 GABA 能中间神经元电路的功能特异性； #2) 研究肌肉源性NT-3对GABA前突触形成的影响；和 #3) 评估角色 Contactin-5 在 GABA 前感觉突触形成中的作用。在第一个目标中，我们结合定时注射他莫昔芬， 小鼠遗传学和 CTb 标记来分析个体 GABApre 的特异性连接是否 中间神经元可能具有功能相关性。在第二个目标中，我们检查 Gabrg1 在 功能上不同的本体感觉感觉神经元，并评估改变 NT-3 水平对两者的影响 Gabrg1 表达和 GABApre 末端编号。在第三个目标中，我们使用扰乱细胞粘附信号 小鼠遗传学并使用分子、显微解剖和功能分析进行表型分析， 包括突触前抑制的电生理学测量。我们还使用体外结合测定 筛选与体内 GABApre 突触特异性相关的新粘附分子候选物。研究 本申请中提出的方法具有创新性，因为它将分子定义的中间神经元电路与 一系列独特的方法将功能特异性与目标衍生信号相结合。研究 将提供对功能多样的 GABApre 电路的理解，并加深我们对 基本电路范例如何适应不同的运动功能。拟议的工作意义重大 因为它将有助于电路级机制和神经元形成的基础知识 CNS中使用的策略；这反过来将推动我们开发有效疗法来重建电路的努力 以及脊髓损伤或其他神经系统疾病后的肌肉功能。