Molecular Organization and Function of Paranodal Axo-glial Junctions

节旁轴胶质细胞连接的分子组织和功能

• 批准号: 10439660
• 负责人: MANZOOR A. BHAT
• 金额: $ 38.75万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10439660
• 关键词: ANK3 gene; Ablation; Action Potentials; Address; Affect; Alleles; Amino Acids; Anodes; Appearance; Architecture; Area; Arthrogryposis; Axon; CNTNAP1 gene; Code; Complex; Congenital Neuropathy; Contracture; Cytoskeletal Proteins; Defect; Disease; Electrophysiology (science); Future; Genes; Genetic; Health; Human; In Vitro; Invertebrates; Joints; Knowledge; Lead; Maintenance; Membrane; Modeling; Molecular; Motor; Motor Neurons; Mus; Muscle; Muscle Weakness; Muscular Atrophy; Mutant Strains Mice; Mutation; Myelin; Nerve; Neural Conduction; Neuromuscular Junction; Neurons; Nodal; Pathology; Phenotype; Physiological; Play; Point Mutation; Potassium Channel; Process; Property; Proteins; Publishing; Ranvier' s Nodes; Role; Scaffolding Protein; Septate; Sodium; Spectrin; Structure; Tertiary Protein Structure; Therapeutic; Therapeutic Intervention; Time; TimeLine; WHRN gene; Work; base; betaIV spectrin; contactin; deafness; design; disability; functional restoration; gain of function; genetic approach; human model; in vivo; insight; interest; motor disorder; mouse model; mutant; neurofascin; neuromuscular; neuropathology; novel; preservation; prevent; protein complex; protein structure; restoration; voltage

Molecular Organization and Function of Paranodal Axo-glial Junctions Myelinated axons are organized into molecularly and functionally distinct domains defined by the presence of specific protein complexes that allow rapid saltatory action potential propagation. The paranodal domain contains the axo-glial junctions (AGJs) that are established by axonal Contactin-associated protein 1 (Cntnap1 or Caspr1), and Contactin (Cntn) and myelin/glial Neurofascin 155 (NF155). The nodal domains (nodes of Ranvier) are organized by neuronal Neurofascin 186 (NF186), voltage-gated sodium (Nav) channels, and two cytoskeletal scaffolding proteins Ankyrin G (AnkG) and βIV Spectrin (βIVSpec). In myelin-related diseases, this domain structure is compromised, leading to a decrease or loss of nerve conduction and muscle weakness. Our work demonstrated specific functions of the above proteins in the organization, maturation and maintenance of axonal domains. We used a novel genetic strategy for nodal domain reorganization in βIVSpec mutants, which allowed restoration of nodal function and prevented motor dysfunction. Importantly, recent identification of human CNTNAP1 mutations that are associated with severe AGJ and myelin defects further highlight the importance of AGJ proteins in nerve structure and function. We have generated new mouse models of three specific human CNTNAP1 mutations (Cys323Arg, Arg388Pro and Arg764Cys). These single amino acid changes in Cntnap1 affect its stability, transport and interactions with Cntn, and lead to disruption of the paranodal domains, and cause severe motor disability. While significant advances have been made regarding the organization of axonal domains; there still remain fundamental overarching questions related to AGJs and neuromuscular health: What impact do human mutations have on AGJ formation and physiological properties of axons? How does progressive disruption of axonal domains affect axons and the muscles they innervate? How does declining nerve activity change neuromuscular junctions (NMJs) and lead to muscle atrophy? In this revised application, we will use mouse models of human CNTNAP1 mutations and axonal domain disorganization and reorganization models to dissect the mechanisms that underlie the organization, maintenance and restoration of axonal domains. Our Specific Aims address three key gaps in knowledge: (1) What impact do human mutations in mouse Cntnap1 have on its structure/function, AGJ formation and axonal domain organization; and do these Cntnap1 mutations cause loss and/or gain of function phenotypes? (2) How does the timeline of axonal domain disorganization in NF186/AnkG mutants correlate with decline in nerve conduction leading to progressive motor disability? And (3) Does nodal domain reorganization and restoration of nerve conduction in bIV Spectrin mutants prevent/reverse muscle atrophy? Collectively, our studies will significantly advance our understanding of how human AGJ- and myelin-related pathologies impact axonal and neuromuscular health; and may offer critical insights into the timelines of functional restoration and potential avenues for future therapeutic interventions for these devastating neuropathologies.

结旁轴-胶质细胞连接的分子结构和功能 有髓鞘的轴突被组织成分子和功能上不同的结构域， 允许快速跳跃动作电位传播的特异性蛋白质复合物。结旁区 包含由轴突接触蛋白相关蛋白1建立的轴胶质连接（AGJ） （Cntnap 1或Caspr 1）和接触蛋白（Cntn）和髓鞘/神经胶质神经成束蛋白155（NF 155）。节点域 （朗维尔结）由神经元成束蛋白186（NF 186），电压门控钠（Nav）通道， 以及两种细胞骨架蛋白Ankyrin G（AnkG）和βIV Spectrin（βIVSpec）。在髓鞘相关的 在疾病中，这种结构域结构受到损害，导致神经传导和肌肉功能的减少或丧失。 弱点我们的工作证明了上述蛋白质在组织、成熟和 轴突结构域的维持。我们使用了一种新的遗传策略在βIVSpec中进行节点域重组 突变体，这允许恢复淋巴结功能和预防运动功能障碍。重要的是，最近 鉴定与严重AGJ和髓磷脂缺陷相关的人CNTNAP 1突变进一步 强调AGJ蛋白在神经结构和功能中的重要性。我们已经生成了新的鼠标 三种特异性人CNTNAP 1突变（Cys 323 Arg、Arg 388 Pro和Arg 764 Cys）的模型。这些单 Cntnap 1的氨基酸变化影响其稳定性、转运以及与Cntn的相互作用，并导致其破坏 并导致严重的运动障碍虽然已经取得了重大进展 关于轴突结构域的组织;仍然存在与以下有关的基本问题： AGJ和神经肌肉健康：人类突变对AGJ形成和生理 轴突的特性轴突结构域的进行性破坏是如何影响轴突和它们所连接的肌肉的？ 神经化？神经活动下降如何改变神经肌肉接头（NMJ）并导致肌肉萎缩？ 萎缩？在这个修改后的申请中，我们将使用人类CNTNAP 1突变和轴突损伤的小鼠模型。 领域分解和重组模型，以剖析组织的基础机制， 轴突域的维持和恢复。我们的具体目标解决知识的三个关键差距：（1） 人类突变对小鼠Cntnap 1的结构/功能、AGJ形成和轴突生长有什么影响？ 这些Cntnap 1突变是否会导致功能表型的丧失和/或获得？(2)如何 NF 186/AnkG突变体轴突结构紊乱的时间轴是否与神经功能衰退相关 传导导致进行性运动障碍以及（3）节点域重组和恢复 bIV Spectrin突变体的神经传导是否能预防/逆转肌肉萎缩？我们的研究将 显著推进了我们对人类AGJ和髓鞘相关病理如何影响轴突和 神经肌肉健康;并可能对功能恢复的时间表和潜在的 这些毁灭性的神经病理学的未来治疗干预的途径。