Node of Ranvier Assembly: Role of Axo-Glial Interactions

Ranvier 组装节点：轴突-神经胶质相互作用的作用

• 批准号: 6875654
• 负责人: JAMES SALZER
• 金额: $ 36.12万
• 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 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6875654
• 关键词: SDS polyacrylamide gel electrophoresis; Schwann cells; axon; cell adhesion molecules; cell cell interaction; fluorescence microscopy; gene expression; gene targeting; genetically modified animals; glia; immunoelectron microscopy; immunoprecipitation; molecular biology; myelination; nerve /myelin protein; node of Ranvier; protein kinase; protein structure function; protein transport; sodium channel; tissue /cell culture

DESCRIPTION (provided by applicant): The striking concentration of Na+ channels at the node results from complex interactions between axons and myelinating glial cells, i.e. Schwann cells in the PNS and oligodendrocytes in the CNS. The nature of these interactions are poorly understood as are the mechanisms by which Na+ channels are targeted to and assemble into a larger complex with other proteins at the node. Associated proteins include the 186 kD isoform of neurofascin, which may bind to receptors on overlying glial processes, and ankyrin G which links cell adhesion molecules to Na+ channels. The node is flanked by paranodal junctions, which are dispensible for initial node formation, but may regulate the maturation and channel density at the node. We propose to address important features of this model by characterizing the targeting of proteins to the node, the role of glial processes that overlie and flank the node and the potential role of neurofascin in directing assembly of the node. Specifically, we will i) determine whether proteins targeted to the node redistribute from existing pools and/or are newly synthesized and transported to this site by labeling live cocultures of neurons with anti-NrCAM Fab fragments as they undergo myelination, analyzing whether nodes form after transecting axons of the Wlds/Ola mouse, and characterizing axonal transport of Na+ channels and other proteins to the node; ii) investigate the role of the ERM+ Schwann cell processes in PNS node formation by blocking their formation by dominant negative strategies or the use of Rho kinase inhibitors; iii) characterize the role of the flanking paranodal processes and junctions in the development and maturation of the node in Caspr deficient mice which lack paranodal junctions focusing on node width, channel density and Na+ channel subtypes and iv) determine the role of the L1 family of cell adhesion molecules, in particular neurofascin, in node formation by generating mice with a conditional, neuron-specific knockout of neurofascin and determine whether they exhibit aberrant initial segment, node or paranode organization and, if minimally affected, by crossing these mice to an existing line of NrCAM knockout mice for analysis of the double knockouts. These studies should provide important new insights into the mechanisms responsible for the assembly of the node, the nature of the glial signals that direct its assembly and may clarify the functional deficits that accompany demyelinating disorders and interrupt normal saltatory conduction.

描述（由申请人提供）：NA+通道的惊人浓度 在轴突和髓鞘之间的复杂相互作用的结果上 神经胶质细胞，即PNS中的雪旺细胞和中枢神经系统中的少突胶质细胞。这 这些相互作用的性质对机制的理解很差 哪些Na+通道针对并组装成一个较大的复合物 节点上的其他蛋白质。相关蛋白包括186 KD的同工型 神经胶质素，它可能与受体结合上层神经胶质过程的受体，并且 将细胞粘附分子与Na+通道联系起来的Ankyrin G。节点是 侧面是偏an道路连接，这对于初始节点来说是可分配的 形成，但可以调节节点处的成熟和通道密度。我们 建议通过表征该模型的重要特征 将蛋白质靶向节点，这是覆盖和的神经胶质过程的作用 侧面节点和神经素在指导组装中的潜在作用 节点。具体来说，我们将）确定蛋白质是否针对 来自现有池的节点重新分布和/或新合成，并且 通过用抗-NRCAM标记神经元的活共培养物来运输到该站点 晶圆厂碎片在发生髓鞘时，分析淋巴结是否形成 WLDS/OLA小鼠的轴突，并表征轴突运输的轴突 Na+通道和其他蛋白质的节点； ii）调查 PNS节点形成中的ERM+ Schwann细胞过程通过阻止其形成 通过主要的负面策略或使用Rho激酶抑制剂的使用； iii） 表征侧翼偏an道路过程和连接处的作用 Caspr缺乏小鼠中节点的发展和成熟 集中于节点宽度，通道密度和Na+通道的偏an道路连接 亚型和IV）确定细胞粘附的L1家族的作用 分子，尤其是神经f，在节点形成中，通过产生小鼠 有条件的神经元特异性敲除神经胶质细胞的敲除，并确定是否是否 它们表现出异常的初始细分市场，节点或paranode组织，如果 通过将这些小鼠越过现有的NRCAM线，受到最小影响 淘汰小鼠以分析双淘汰赛。这些研究应该 对负责集会的机制提供重要的新见解 节点，指导其组装的胶质信号的性质，可能 澄清脱髓鞘疾病随附的功能缺陷和 中断正常的盐传导。