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: 10225351
• 负责人: MANZOOR A. BHAT
• 金额: $ 38.71万
• 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/10225351
• 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.

节旁轴胶质细胞连接的分子组织和功能 有髓轴突被组织成分子和功能上不同的域，这些域由存在的定义 允许快速跳跃动作电位传播的特定蛋白质复合物。节旁域 包含由轴突接触蛋白相关蛋白 1 建立的轴突胶质细胞连接 (AGJ) （Cntnap1 或 Caspr1）、Contactin (Cntn) 和髓磷脂/神经胶质神经成束蛋白 155 (NF155)。节点域 （Ranvier 节点）由神经元 Neurofascin 186 (NF186)、电压门控钠 (Nav) 通道组织， 以及两种细胞骨架支架蛋白锚蛋白 G (AnkG) 和 βIV 血影蛋白 (βIVSpec)。与髓磷脂相关 疾病时，该域结构受到损害，导致神经传导和肌肉减少或丧失 弱点。我们的工作证明了上述蛋白质在组织、成熟和发育过程中的特定功能。 轴突域的维护。我们在 βIVSpec 中使用了一种新颖的遗传策略进行节点域重组 突变体，可以恢复淋巴结功能并防止运动功能障碍。重要的是，最近 进一步鉴定与严重 AGJ 和髓磷脂缺陷相关的人类 CNTNAP1 突变 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 三种特定人类 CNTNAP1 突变（Cys323Arg、Arg388Pro 和 Arg764Cys）的模型。这些单 Cntnap1 中的氨基酸变化会影响其稳定性、运输以及与 Cntn 的相互作用，并导致破坏 节旁区域，并导致严重的运动障碍。虽然已经取得了重大进展 关于轴突域的组织；仍然存在与以下方面有关的根本性总体问题 AGJ 和神经肌肉健康：人类突变对 AGJ 形成和生理有什么影响 轴突的特性？轴突域的渐进性破坏如何影响轴突及其肌肉 支配？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？在此修订后的申请中，我们将使用人类 CNTNAP1 突变和轴突的小鼠模型 领域解组织和重组模型来剖析组织背后的机制， 轴突域的维护和恢复。我们的具体目标解决了知识方面的三个关键差距：(1) 小鼠 Cntnap1 的人类突变对其结构/功能、AGJ 形成和轴突有何影响 域组织；这些 Cntnap1 突变是否会导致功能表型的丧失和/或增强？ (2) 如何 NF186/AnkG 突变体中轴突结构域解体的时间线是否与神经衰退相关 传导导致进行性运动障碍？ (3)节点域是否重组和恢复 bIV Spectrin 突变体中神经传导的作用可预防/逆转肌肉萎缩？总的来说，我们的研究将 显着促进我们对人类 AGJ 和髓磷脂相关病理如何影响轴突和髓磷脂的理解 神经肌肉健康；并可能为功能恢复的时间表和潜力提供重要的见解 未来对这些破坏性神经病理学进行治疗干预的途径。