Assembly of the Node of Ranvier

朗飞节点集会

• 批准号: 7363673
• 负责人: JAMES SALZER
• 金额: $ 37.03万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7363673
• 关键词: Action Potentials; Address; Ankyrins; Axon; Binding; Cell surface; Coculture Techniques; Complex; Cytoplasmic Tail; Cytoskeletal Proteins; Demyelinations; Dependence; Development; Diffuse; Disease; Epitopes; Fiber; Foundations; Image; In Situ; Label; Life; Localized; Maintenance; Mediating; NRCAM gene; Neuroglia; Nodal; Numbers; Pathogenesis; Photobleaching; Positioning Attribute; Proteins; Ranvier' s Nodes; Recruitment Activity; Role; Signal Transduction; Site; Sodium Channel; Sorting - Cell Movement; Source; Specific qualifier value; Spectrin; Surface; Transgenic Mice; Transport Vesicles; extracellular; insight; intracellular protein transport; neurofascin; nodal protein; novel; protein transport; trafficking; voltage

DESCRIPTION (provided by applicant): Action potentials are generated at the axon initial segment (AIS) and are propagated via saltatory conduction at nodes of Ranvier. These domains are highly enriched in voltage gated Na+ channels, which form a multimeric complex with beta subunits, neuronal cell adhesion molecules, notably neurofascin (NF) 186, and the cytoskeletal proteins ankyrin G and piv spectrin. We have recently demonstrated that targeting of NF186 to PNS nodes is mediated via its extracellular interactions, that it has an essential role in node formation by recruiting ankyrin G via its cytoplasmic domain, and that ankyrin G in turn, is required for the accumulation of sodium channels. In contrast, ankyrin accumulation at initial segments, which is also critical for domain organization is intrinsically specified, independent of NF186. These studies raise a number of key questions. What is the source of proteins targeted to the node and how do they traffic to this site? Are nodal components, once assembled, stably expressed at the node or do they continuously turnover and, if so, is this turnover enhanced by demyelination? Finally, do CNS nodes assemble like PNS nodes (i.e. directed by extracellular signals) or more akin to initial segments (i.e. directed from the inside-out via interactions with ankyrin G)? In this proposal, we address these questions and further characterize mechanisms of node assembly by: i) determining how proteins traffic to PNS nodes, including whether they are recruited from cell surface pools or via directed vesicular transport, ii) live image nodes to examine dynamic changes that occur during development and with demyelination, and iii) examine the dependence of CNS nodes on NF186- dependent signals in cocultures and targeting signals in transgenic mice. These studies should provide important new insights into the axo-glial interactions that regulate the assembly and maintenance of nodes of Ranvier. They will also be an important foundation for elucidating pathogenetic changes at nodes that result from demyelination.

描述（由申请人提供）：动作电位在轴突起始段（AIS）处产生，并通过朗飞节点处的跳跃传导传播。这些结构域在电压门控 Na+ 通道中高度富集，与 β 亚基、神经元细胞粘附分子（尤其是神经成束蛋白 (NF) 186）以及细胞骨架蛋白锚蛋白 G 和 piv 血影蛋白形成多聚体复合物。我们最近证明，NF186 靶向 PNS 节点是通过其细胞外相互作用介导的，它通过其细胞质结构域募集锚蛋白 G 在节点形成中发挥重要作用，而锚蛋白 G 又是钠积累所必需的渠道。相比之下，初始片段处的锚蛋白积累对于结构域组织也至关重要，其本质上是特定的，独立于 NF186。这些研究提出了一些关键问题。针对该节点的蛋白质来源是什么？它们如何传输到该站点？节点成分一旦组装后，是否会在节点稳定表达，或者它们是否持续更新，如果是这样，这种更新是否会因脱髓鞘而增强？最后，CNS 节点的组装是否像 PNS 节点（即由细胞外信号引导）或更类似于初始片段（即通过与锚蛋白 G 相互作用从内到外引导）？在本提案中，我们通过以下方式解决这些问题并进一步描述节点组装的机制：i）确定蛋白质如何运输到 PNS 节点，包括它们是从细胞表面池还是通过定向囊泡运输招募，ii）实时图像节点以检查动态iii) 检查共培养物中 CNS 节点对 NF186 依赖性信号的依赖性以及转基因小鼠中的靶向信号。这些研究应该为调节朗飞节点的组装和维护的轴神经胶质相互作用提供重要的新见解。它们也将成为阐明脱髓鞘引起的淋巴结致病变化的重要基础。