Molecular Organization and Function of Paranodal Axo-Glial Junctions

节点旁轴突胶质细胞连接的分子组织和功能

• 批准号: 8630674
• 负责人: MANZOOR A. BHAT
• 金额: $ 33.18万
• 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 2018-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8630674
• 关键词: Ablation; Action Potentials; Adaptor Signaling Protein; Adult; Affect; Ankyrins; Appearance; Architecture; Area; Axon; Biological; Cells; Clinical; Cytoskeletal Proteins; Cytoskeleton; Defect; Demyelinating Diseases; Demyelinations; Development; Disease; Employee Strikes; Ensure; Future; Genes; Genetic; Goals; Health; In Vitro; Invaded; Invertebrates; Ion Channel; Lead; Life; Long-Term Effects; Maintenance; Membrane; Methods; Molecular; Molecular Genetics; Multiple Sclerosis; Mutant Strains Mice; Myelin; Myelinated nerve fiber; Nerve; Neural Conduction; Neuroglia; Neurons; Nodal; Play; Potassium Channel; Proteins; Publishing; Reagent; Role; Scaffolding Protein; Septate; Sodium; Structure; Therapeutic; Therapeutic Intervention; Ursidae Family; base; contactin; design; disability; functional restoration; in vivo; insight; interest; mutant; myelinopathy; neurofascin; novel; public health relevance; remyelination; restoration; voltage

The hallmark of myelinated axons is their organization into molecularly distinct domains, a pre-requisite for the rapid propagation of action potentials. The paranodal domains establish the axo-glial septate junctions (AGSJs) through interactions involving axonal Contactin-associated protein (Caspr), Contactin (Cont), and glial Neurofascin NF155. The nodal domain is organized by neuronal NF186, voltage gated sodium (Nav) channels, and Ankyrin G (AnkG), a cytoskeletal adaptor protein. We showed that loss of Caspr and NF155 results in loss of AGSJs, mislocalization of the juxtaparanodal proteins, disorganization of the paranodal axonal cytoskeleton, and degeneration of myelinated axons, but nodal organization remains relatively unaffected. Recently, we showed that Band 4.1B, a paranodal/ juxtaparanodal cytoskeletal protein, is essential for the stability of AGSJs and juxtaparanodal organization. We show here that Whirlin, another cytoskeletal protein, is required for paranodal compaction and cytoskeletal stability. In further studies, we demonstrated that loss of nodal NF186 abolished clustering of Nav channels and AnkG at the nodes, allowing the flanking paranodal AGSJs to invade the nodal space. Most importantly, we show here that in vivo loss of AnkG does not abolish node formation, but may affect nodal stability. While significant advancements have been made regarding the composition and organization of axonal domains, there still remain fundamental questions regarding how the transmembrane components at these domains interact with local cytoskeleton to initiate domain organization, and to ensure long-term stability and maintenance of axonal architecture. Based on our published and preliminary studies, our central hypothesis is that the transmembrane components and local axonal cytoskeleton are critical for axonal domain organization, their stability and function. We will use genetic, molecular and cell biological methods to determine the specific role of paranodes, nodes and their associated cytoskeletal proteins in domain stabilization and maintenance, and the efficacy of restoration of key axonal domains by re-expression of NF155 and NF186 in progressively weak adult mouse mutants. We will accomplish our goals in the following specific aims: (1) What are the consequences of loss of cytoskeletal scaffolding proteins and loss of NF155 during adult life on the maintenance and function of paranodal AGSJs? (2) What are the consequences of loss of nodal cytoskeletal proteins and loss of NF186 during adult life on the stability and function of nodes in myelinated axons? and (3) Are adult myelinated axons with extended periods of disorganized domain structure able to re-organize axonal domains to restore nerve conduction? Collectively, our studies will provide insights that bear directly on the mechanisms by which axonal domains are formed and maintained, and how these structures can be reorganized and nerve function restored. In the future, these studies will advance our understanding of how demyelinating diseases, such as multiple sclerosis (MS) lead to axonal domain disorganization and guide the development of therapeutic interventions.

髓鞘轴突的标志是它们的组织进入分子不同的域，这是该域的先决条件 动作电位的快速传播。偏向域建立了Axo-Glial分隔连接 （AGSJS）通过涉及轴突接触蛋白相关蛋白（CASPR），contactin（续）和的相互作用 神经胶质神经素NF155。节点结构域由NF186，电压门钠（NAV）组织 通道和Ankyrin G（ANKG），一种细胞骨骼衔接蛋白。我们显示了CASPR和NF155的损失 导致AGSJS的损失，近距离蛋白的错误定位，paranodal的混乱 轴突细胞骨架和髓鞘轴突的变性，但淋巴结组织保持相对 不受影响。最近，我们表明Band 4.1b是一种偏anod骨/近齿状细胞骨架蛋白，是必不可少的 为了稳定AGSJS和juxtaparanodal组织。我们在这里表明旋风，另一个细胞骨架 蛋白质是偏阳压体和细胞骨架稳定性所必需的。在进一步的研究中，我们证明了 节点NF186的损失消除了节点处的NAV通道和ANKG的聚类，从而允许侧翼 偏执的AGSJS入侵节点空间。最重要的是，我们在这里表明，体内ANKG的损失确实 不是废除淋巴结的形成，但可能会影响淋巴结稳定性。尽管已经取得了重大进步 关于轴突域的组成和组织，仍然存在基本问题 关于这些结构域的跨膜成分如何与局部细胞骨架相互作用以启动 域组织，并确保轴突架构的长期稳定性和维护。基于我们 发表和初步研究，我们的中心假设是跨膜成分和 局部轴突细胞骨架对于轴突结构域组织至关重要，其稳定性和功能。我们 将使用遗传，分子和细胞生物学方法来确定偏态，节点和 它们在域稳定和维护中相关的细胞骨架蛋白，以及恢复的功效 通过在逐渐弱的成年小鼠突变体中重新表达NF155和NF186的关键轴突结构域。我们 将在以下特定目标中实现我们的目标：（1）损失细胞骨骼的后果是什么 在成年人生活中，脚手架蛋白质和NF155的损失在旁糖AGSJ的维持和功能方面？ （2）在成人生活期间，淋巴结细胞骨架蛋白丧失和NF186损失的后果是什么 骨髓轴突中节点的稳定性和功能？ （3）是成年骨髓轴突，长时间 混乱的结构域结构能够重组轴突结构域以恢复神经传导？ 总的来说，我们的研究将提供直接对轴突域的机制的见解 形成和维护，以及如何重组这些结构并恢复神经功能。在 未来，这些研究将促进我们对脱髓鞘疾病的理解，例如多发性硬化症 （MS）导致轴突域混乱并指导治疗干预措施的发展。