Neuroglial interactions at the node of Ranvier

描述（申请人提供）：有髓鞘轴突中的离子通道聚集对于神经系统的正常功能至关重要。离子通道通过神经元-神经胶质相互作用聚集在Ranvier节点上。然而，负责通道集群的机制仍然知之甚少。最近的研究表明，多种机制可能有助于节点的形成。其中，由锚蛋白和谱蛋白组成的轴突膜下细胞骨架被认为是关键成分。特别是Ranvier节点本身富含ankyrinG （ankG）和？四血影蛋白;ankG被认为直接与Na+和K+通道结合，然后通过？四世血影蛋白。在偏执狂中，无论是踝关节还是？II型幽灵是聚集的，尽管它们在偏执狂中的功能尚不清楚。偏执狂也被认为是副神经扩散屏障和第二种机制，调解离子通道聚集在节点上，尽管负责这种屏障功能的机制尚不清楚。此外，阐明偏执狂功能的一个主要障碍是在该位点鉴定的蛋白质相对较少。在这个建议中，我们将试图确定节点和旁结细胞骨架在朗维耶组装和维持节点中的功能。我们将使用三种利用Cre-Lox技术控制ankG、ankB和？二世血影蛋白。我们将沉默这些蛋白在周围感觉神经元、视网膜神经节细胞和髓鞘胶质细胞在发育和成人中的表达。最后，我们将使用蛋白质组学方法鉴定新的副淋巴结蛋白，然后寻求确定其功能。

DESCRIPTION (provided by applicant): Ion channel clustering in myelinated axons is essential for proper nervous system function. Ion channels are clustered at nodes of Ranvier through neuron-glia interactions. However, the mechanisms responsible for channel clustering remain poorly understood. Recent studies suggest that multiple mechanisms may contribute to node formation. Among these, the axonal submembranous cytoskeleton comprised of ankyrins and spectrins has been proposed to be key components. In particular, nodes of Ranvier themselves are enriched with ankyrinG (ankG) and ?IV spectrin; ankG is thought to bind directly to the Na+ and K+ channels, and then link to the actin cytoskeleton through ?IV spectrin. At paranodes, both ankyrinB and ?II spectrin are clustered, although their functions at paranodes remain unknown. Paranodes are also thought to function as a paranodal diffusion barrier and a second mechanism to mediate ion channel clustering at nodes, although the mechanisms responsible for this barrier function remain unknown. Furthermore, a major impediment to elucidating the function of paranodes is the relatively few proteins that have been identified at this site. In this proposal we will seek to determine the function of the nodal and paranodal cytoskeletons in node of Ranvier assembly and maintenance. We will do this using three new mouse models that utilize Cre-Lox technology to control the temporal and spatial (cell-type specific) expression of ankG, ankB, and ?II spectrin. We will silence expression of these proteins in peripheral sensory neurons, in retinal ganglion cells, and in myelinating glia during both development and in adults. Finally, we will use proteomic methods to identify new paranodal proteins, and then seek to determine their functions.