Mechanisms of Node of Ranvier Assembly

Ranvier组装节点机制

• 批准号: 8675608
• 负责人: JAMES SALZER
• 金额: $ 35.75万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-11 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8675608
• 关键词: Action Potentials; Address; Affect; Anabolism; Ankyrins; Axon; Axonal Transport; Binding; Cell Adhesion Molecules; Characteristics; Coculture Techniques; Complex; Cytoplasmic Tail; Cytoskeletal Proteins; Data; Development; Diffusion; Disease; Employee Strikes; Endocytosis; Exhibits; Extranodal; Fiber; Image; Ion Channel; Label; Lateral; Lead; Life; Ligands; Metalloproteases; NRCAM gene; Nerve Fibers; Neural Conduction; Neuroglia; Neurons; Neuropathy; Nodal; Pathogenesis; Potassium Channel; Proteolysis; Ranvier' s Nodes; Recruitment Activity; Role; Route; SCN2A protein; Schwann Cells; Signal Transduction; Site; Sodium Channel; Source; Specificity; Spectrin; Surface; Transport Vesicles; Vesicle; cellular microvillus; insight; myelination; nervous system disorder; neurofascin; nodal protein; novel; novel therapeutics; programs; trafficking; voltage

The nodes of Ranvier of myelinated axons are critical for action potential propagation by saltatory conduction and are a striking example of the exquisite domain organization characteristic of neurons. Nodes are comprised of a multimeric complex that includes voltage gated sodium and potassium channels, accessory beta subunits, cell adhesion molecules (CAMs), and a cytoskeletal complex that includes ankyrin G to which channels and CAMs bind. Our recent studies indicate that the node assembles from distinct sources. CAMs, notably NF186, accumulate at forming nodes by redistribution from existing pools on the axon surface via diffusion trapping from interactions with the Schwann cell. In contrast, channels and cytoskeletal proteins are delivered to the node primarily via axonal transport. Surprisingly, there also appears to be a pool of sodium channels that traffics and accumulates at the node independent of transport and of ankyrin G. Finally, our studies suggest there is an active program to clear nodal proteins from extranodal sites that further reinforces their selective enrichment at the node. To extend these findings and further elucidate the mechanisms of node assembly, we will investigate trafficking and assembly of components of the node, and how they are cleared from extranodal sites, by live imaging strategies in myelinating cocultures. In particular, we will: i) determine whether vesicles that transport components to the nodes segregate into those specific for CAMs and others for ion channels, and exhibit any domain specificity, ii) characterize transport-dependent and -independent trafficking of sodium channel components to the node, including the roles of ankyrin G and NF186, respectively, and determine whether the sodium channel complex assembles locally, and i) investigate how nodal components are cleared from extranodal sites, focusing on NF186 to examine further the role of its cytoplasmic segment and that of endocytosis and proteolysis in clearing the internodal, surface pool of NF186. Relevance: These studies will elucidate the mechanisms that regulate the assembly of the node of Ranvier, which is critical to the ability of nerve fibers to conduct electrical impulses appropriately. Findings in this study may therefore have important implications for our understanding of the pathogenesis of disorders of myelinated fibers, including neuropathies that result in aberrant nerve conduction, and may thereby lead to new therapeutic strategies for these neurological disorders.

髓鞘轴突的兰维尔节点对于通过盐传导进行动作势传播至关重要，并且是神经元的精致域组织特征的一个显着例子。节点由一个多聚体复合物组成，其中包括电压门控钠和钾通道，辅助β亚基，细胞粘附分子（CAM）以及一个细胞骨架络合物，其中包括Ankyrin g的通道和CAM结合的通道和CAM。我们最近的研究表明，节点是从不同来源组装的。凸轮，尤其是NF186，通过从与Schwann细胞的相互作用中捕获轴突表面上现有池的重新分布来积聚在形成节点上。相反，通道和细胞骨架蛋白主要通过轴突转运传递到节点。令人惊讶的是，似乎也有一系列的钠通道，这些通道池在传输和弯道G的节点上进行流量和积累。最后，我们的研究表明，有一个积极的程序可以清除淋巴结外蛋白质，从而从外座点上清除淋巴结蛋白，从而进一步增强其在节点上的选择性富集。为了扩展这些发现并进一步阐明了节点组装的机制，我们将通过髓鞘培养的实时成像策略来研究节点组件的运输和组件，以及如何从外座位点清除它们。 In particular, we will: i) determine whether vesicles that transport components to the nodes segregate into those specific for CAMs and others for ion channels, and exhibit any domain specificity, ii) characterize transport-dependent and -independent trafficking of sodium channel components to the node, including the roles of ankyrin G and NF186, respectively, and determine whether the sodium channel complex assembles locally, and i) investigate how从旋道外部位清除了淋巴结成分，重点是NF186，以进一步研究其细胞质段以及内吞作用和蛋白水解在清除NF186表面库中的作用。相关性：这些研究将阐明调节Ranvier节点组装的机制，这对于神经纤维适当地进行电脉冲的能力至关重要。因此，这项研究中的发现可能对我们对髓鞘纤维疾病的发病机理的理解具有重要意义，包括导致神经传导异常的神经病，从而导致这些神经系统疾病的新治疗策略。