Ultrastructural localization of Shaker-related potassium channel subunits and synapse-associated protein 90 to septate-like junctions in rat cerebellar Pinceaux
Ultrastructural localization of Shaker-related potassium channel subunits and synapse-associated protein 90 to septate-like junctions in rat cerebellar Pinceaux
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DOI：
10.1016/s0169-328x(96)00120-9
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发表时间：
1996-11-01
期刊：
影响因子：
--
通讯作者：
Veh, RW
中科院分区：
文献类型：
--
作者：
Laube, G;Roper, J;Veh, RW
平索是小脑篮状细胞轴突分支的画笔状网络，其包围浦肯野细胞轴突的起始段。它的电活动通过产生抑制场效应，有助于通过浦肯野细胞轴突控制小脑皮质输出。除了Pinceau的结构特征外，其电压门控离子通道库可能是这一功能的一个重要方面，因此，我们研究了Pinceau中电压激活的钾（K（V）1.1，K（V）1.2，K（V）3.4）和钠通道蛋白的精细结构分布。将钾通道亚基的超微结构定位与突触相关蛋白90（SAP 90）的分布进行比较，SAP 90是一种能够诱导K（V）1蛋白体外聚集的蛋白质。通过一种改进的包埋前技术，包括超小的金颗粒，银增强和金调色，我们可以表明，抗体识别K（V）1.1，K（V）1.2和SAP 90主要定位于隔样连接，连接篮状细胞轴突分支。K（V）3.4免疫反应不集中于连接区，而是均匀分布于Pinceau和浦肯野细胞周围的细胞周围篮。与此相反，电压激活的钠离子通道没有检测到的平索，但本地化的浦肯野细胞轴突起始段。结果表明，K（V）1.1和K（V）1.2形成异源寡聚延迟整流型K-V通道，通过与SAP 90相互作用共定位于隔样连接。
The Pinceau is a paintbrush-like network of cerebellar basket cell axon branchlets embracing the initial segment of the Purkinje cell axon. Its electrical activity contributes to the control of the cerebellar cortical output through the Purkinje cell axon by generating an inhibitory field effect. In addition to the structural features of the Pinceau, its repertoire of voltage-gated ion channels is likely to be an important aspect of this function, Therefore, we investigated the fine structural distribution of voltage-activated potassium (K(V)1.1, K(V)1.2, K(V)3.4) and sodium channel proteins in the Pinceau. The ultrastructural localization of potassium channel subunits was compared to the distribution of synapse-associated protein 90 (SAP90), a protein capable to induce in vitro clustering of K(V)1 proteins. With an improved preembedding technique including ultrasmall gold particles, silver enhancement and gold toning, we could show that antibodies recognizing K(V)1.1, K(V)1.2 and SAP90 are predominantly localized to septate-like junctions, which connect the basket cell axonal branchlets. K(V)3.4 immunoreactivity is not concentrated in junctional regions but uniformly distributed over the Pinceau and the pericellular basket surrounding the Purkinje cell some. In contrast, voltage-activated sodium channels were not detected in the Pinceau, but localized to the Purkinje cell axon initial segment. The results suggest that K(V)1.1 and K(V)1.2 form heterooligomeric delayed rectifier type K-V channels, being colocalized to septate-like junctions by interaction with SAP90.