Kaplan M R, Meyer-Franke A, Lambert S, Bennett V, Duncan I D, Levinson S R, Barres B A
Stanford University School of Medicine, Department of Neurobiology, California 94305, USA.
Nature. 1997 Apr 17;386(6626):724-8. doi: 10.1038/386724a0.
As oligodendrocytes wrap axons of the central nervous system (CNS) with insulating myelin sheaths, sodium channels that are initially continuously distributed along axons become segregated into regularly spaced gaps in the myelin called nodes of Ranvier. It is not known whether the regular spacing of nodes results from regularly spaced glial contacts or is instead intrinsically specified by the axonal cytoskeleton. Contact with Schwann cells induces clustering of sodium channels along the axons of peripheral neurons in vitro and in vivo. Similarly, it has been suggested that astrocyte contact induces clustering of sodium channels along CNS axons. Here we show that oligodendrocytes are necessary for clustering of sodium channels in vitro and in vivo. The induction, but not the maintenance, of sodium-channel clustering along the axons of highly purified rat retinal ganglion cells in culture depends on a protein secreted by oligodendrocytes. Surprisingly, the oligodendrocyte-induced clusters are regularly spaced at the predicted interval in the absence of glial-axonal contact. Mutant rats that are deficient in oligodendrocytes develop few axonal sodium channel clusters in vivo. These results demonstrate a crucial role for oligodendrocytes in inducing clustering of sodium channels.
少突胶质细胞用绝缘的髓鞘包裹中枢神经系统（CNS）的轴突，最初沿轴突连续分布的钠通道会分隔成髓鞘中规则间隔的间隙，即郎飞结。尚不清楚节点的规则间距是由规则间隔的胶质细胞接触导致的，还是由轴突细胞骨架内在决定的。在体外和体内，与施万细胞的接触都会诱导外周神经元轴突上钠通道的聚集。同样，有人提出星形胶质细胞的接触会诱导中枢神经系统轴突上钠通道的聚集。在此我们表明，少突胶质细胞在体外和体内对钠通道的聚集是必需的。在培养的高度纯化的大鼠视网膜神经节细胞轴突上，钠通道聚集的诱导而非维持，依赖于少突胶质细胞分泌的一种蛋白质。令人惊讶的是，在没有胶质细胞 - 轴突接触的情况下，少突胶质细胞诱导的簇以预测的间隔规则排列。少突胶质细胞缺陷的突变大鼠在体内形成的轴突钠通道簇很少。这些结果证明了少突胶质细胞在诱导钠通道聚集方面的关键作用。
