University of Edinburgh, Centre for Neuroregeneration, Edinburgh EH16 4SB, United Kingdom.
J Neurosci. 2011 Dec 7;31(49):18185-94. doi: 10.1523/JNEUROSCI.4936-11.2011.
Myelinated axons have a distinct protein architecture essential for action potential propagation, neuronal communication, and maintaining cognitive function. Damage to myelinated axons, associated with cerebral hypoperfusion, contributes to age-related cognitive decline. We sought to determine early alterations in the protein architecture of myelinated axons and potential mechanisms after hypoperfusion. Using a mouse model of hypoperfusion, we assessed changes in proteins critical to the maintenance of paranodes, nodes of Ranvier, axon-glial integrity, axons, and myelin by confocal laser scanning microscopy. As early as 3 d after hypoperfusion, the paranodal septate-like junctions were damaged. This was marked by a progressive reduction of paranodal Neurofascin signal and a loss of septate-like junctions. Concurrent with paranodal disruption, there was a significant increase in nodal length, identified by Nav1.6 staining, with hypoperfusion. Disruption of axon-glial integrity was also determined after hypoperfusion by changes in the spatial distribution of myelin-associated glycoprotein staining. These nodal/paranodal changes were more pronounced after 1 month of hypoperfusion. In contrast, the nodal anchoring proteins AnkyrinG and Neurofascin 186 were unchanged and there were no overt changes in axonal and myelin integrity with hypoperfusion. A microarray analysis of white matter samples indicated that there were significant alterations in 129 genes. Subsequent analysis indicated alterations in biological pathways, including inflammatory responses, cytokine-cytokine receptor interactions, blood vessel development, and cell proliferation processes. Our results demonstrate that hypoperfusion leads to a rapid disruption of key proteins critical to the stability of the axon-glial connection that is mediated by a diversity of molecular events.
有髓轴突具有独特的蛋白质结构，对于动作电位的传播、神经元通讯和维持认知功能至关重要。与脑灌注不足相关的有髓轴突损伤导致与年龄相关的认知能力下降。我们试图确定灌注不足后有髓轴突蛋白质结构的早期变化和潜在机制。使用灌注不足的小鼠模型，我们通过共焦激光扫描显微镜评估了对维持连接结、Ranvier 结、轴突-胶质完整性、轴突和髓鞘至关重要的蛋白质的变化。早在灌注不足 3 天后，连接结的分隔样连接就受到了损伤。这表现为连接结 Neurofascin 信号的逐渐减少和分隔样连接的丢失。与连接结破坏同时发生的是 Nav1.6 染色的节点长度显著增加，这与灌注不足有关。髓鞘相关糖蛋白染色的空间分布变化也表明灌注不足后轴突-胶质完整性受到破坏。这些节点/连接结的变化在灌注不足 1 个月后更为明显。相比之下，节点锚定蛋白 AnkyrinG 和 Neurofascin 186 没有变化，灌注不足时轴突和髓鞘完整性没有明显变化。对脑白质样本的微阵列分析表明，有 129 个基因发生了显著改变。随后的分析表明，包括炎症反应、细胞因子-细胞因子受体相互作用、血管发育和细胞增殖过程在内的生物学途径发生了改变。我们的结果表明，灌注不足导致对轴突-胶质连接稳定性至关重要的关键蛋白迅速破坏，这是由多种分子事件介导的。
