Neuroscience Institute, New York University Langone Medical Center, New York, NY, USA.
Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Adv Exp Med Biol. 2019;1190:107-122. doi: 10.1007/978-981-32-9636-7_8.
Enriched Na channel clustering allows for rapid saltatory conduction at a specialized structure in myelinated axons, the node of Ranvier, where cations are exchanged across the axon membrane. In the extracellular matrix (ECM), highly negatively charged molecules accumulate and wrap around the nodal gaps creating an ECM dome, called the perinodal ECM. The perinodal ECM has different molecular compositions in the central nervous system (CNS) and peripheral nervous system (PNS). Chondroitin sulfate proteoglycans are abundant in the ECM at the CNS nodes, whereas heparan sulfate proteoglycans are abundant at the PNS nodes. The proteoglycans have glycosaminoglycan chains on their core proteins, which makes them electrostatically negative. They associate with other ECM molecules and form a huge stable ECM complex at the nodal gaps. The polyanionic molecular complexes have high affinity to cations and potentially contribute to preventing cation diffusion at the nodes.In this chapter, we describe the molecular composition of the perinodal ECM in the CNS and PNS, and discuss their physiological role at the node of Ranvier.
富含钠通道的簇集允许在有髓轴突的特殊结构——郎飞结处进行快速跳跃传导，郎飞结是阳离子穿过轴突膜进行交换的部位。在细胞外基质 (ECM) 中，高度带负电荷的分子聚集并包裹在节间间隙周围，形成 ECM 穹顶，称为节周 ECM。节周 ECM 在中枢神经系统 (CNS) 和周围神经系统 (PNS) 中的分子组成不同。硫酸软骨素蛋白聚糖在 CNS 节点的 ECM 中丰富，而硫酸乙酰肝素蛋白聚糖在 PNS 节点中丰富。蛋白聚糖的核心蛋白上有糖胺聚糖链，使其具有静电负性。它们与其他 ECM 分子结合，在节间间隙形成巨大的稳定 ECM 复合物。多阴离子分子复合物对阳离子具有高亲和力，并可能有助于防止节点处阳离子扩散。在本章中，我们描述了 CNS 和 PNS 中节周 ECM 的分子组成，并讨论了它们在郎飞结处的生理作用。
