Expression and Clustered Distribution of an Inwardly Rectifying Potassium Channel, KAB-2/Kir4.1, on Mammalian Retinal Müller Cell Membrane: Their Regulation by Insulin and Laminin Signals
Expression and Clustered Distribution of an Inwardly Rectifying Potassium Channel, KAB-2/Kir4.1, on Mammalian Retinal Müller Cell Membrane: Their Regulation by Insulin and Laminin Signals
复制标题
DOI：
10.1523/jneurosci.17-20-07725.1997
复制
发表时间：
1997-10
期刊：
影响因子：
--
通讯作者：
Masaru Ishii;Y. Horio;Yoshihiko Tada;H. Hibino;A. Inanobe;M. Ito;M. Yamada;T. Gotow;Y. Uchiyama;Y. Kurachi
中科院分区：
文献类型：
--
作者：
Masaru Ishii;Y. Horio;Yoshihiko Tada;H. Hibino;A. Inanobe;M. Ito;M. Yamada;T. Gotow;Y. Uchiyama;Y. Kurachi
Müller 细胞（视网膜中的主要神经胶质细胞）中的内向整流钾 (K+) 通道 (Kir) 被认为负责 K+ 离子的空间缓冲作用。通过电生理学、分子生物学和免疫染色技术，研究了大鼠和兔视网膜 Müller 细胞 Kir 通道的分子特性和亚细胞定位。从 Müller 细胞的尾足到远端部分，只能记录到单个 Kir 通道活性群体，其特性与 HEK293T 细胞中表达的 KAB-2/Kir4.1 的特性相同。一致地，Northern印迹、原位杂交和RT-PCR分析表明Kir4.1在Müller细胞本身中表达。 Kir4.1 免疫反应性呈簇分布在整个 Müller 细胞膜上。 Müller细胞中的Kir4.1表达在培养后立即消失。当解离的 Müller 细胞在存在胰岛素的情况下在层粘连蛋白包被的培养皿上培养时，在细胞膜上以簇状方式检测到 Kir4.1 免疫反应性。由于视网膜Müller细胞周围存在胰岛素和层粘连蛋白，这些物质可能是体内Müller细胞中Kir4.1表达和分布的生理调节因子。
Inwardly rectifying potassium (K+) channels (Kir) in Müller cells, the dominant glial cells in the retina, are supposed to be responsible for the spatial buffering action of K+ ions. The molecular properties and subcellular localization of Müller cell Kir channels in rat and rabbit retinas were examined by using electrophysiological, molecular biological, and immunostaining techniques. Only a single population of Kir channel activity, the properties of which were identical to those of KAB-2/Kir4.1 expressed in HEK293T cells, could be recorded from endfoot to the distal portion of Müller cells. Consistently, Northern blot, in situ hybridization, and RT-PCR analyses indicated expression of Kir4.1 in Müller cells per se. The Kir4.1 immunoreactivity was distributed in clusters throughout Müller cell membrane. The Kir4.1 expression in Müller cells disappeared promptly after culturing. When the dissociated Müller cells were cultured on laminin-coated dishes in the presence of insulin, Kir4.1 immunoreactivity was detected in a clustered manner on the cell membrane. Because insulin and laminin exist in the surrounding of Müller cells in the retina, these substances possibly may be physiological regulators of expression and distribution of Kir4.1 in Müller cells in vivo.