Epithelial sodium channels (ENaC) are uniformly distributed on motile cilia in the oviduct and the respiratory airways
Epithelial sodium channels (ENaC) are uniformly distributed on motile cilia in the oviduct and the respiratory airways
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DOI：
10.1007/s00418-011-0904-1
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发表时间：
2012-03-01
影响因子：
2.3
通讯作者：
Hanukoglu, Aaron
中科院分区：
文献类型：
--
作者：
Enuka, Yehoshua;Hanukoglu, Israel;Hanukoglu, Aaron
上皮钠通道（ENaCs）位于细胞的顶端表面，并将Na+离子从管腔漏斗进入细胞。ENaC功能还调节细胞外液体积，因为水流过伴随Na+离子的膜以维持渗透压。为了检测ENaC的表达位点和细胞内定位，我们制备了针对我们在大肠杆菌中表达的人α-ENaC亚基胞外结构域的多克隆抗体。杆菌使用这些抗体的免疫荧光的三维（3D）共聚焦显微镜首次揭示，ENaCs均匀分布在纤毛表面上的所有上皮细胞与运动纤毛内衬支气管在人肺和女性生殖道，所有沿着输卵管的伞端，壶腹和罕见的细胞在子宫腺。定量分析表明，纤毛使细胞表面积增加> 70倍，纤毛上的ENaC的量比非纤毛细胞表面上的ENaC的量高> 1，000倍。这些发现表明ENaC具有调节沐浴纤毛的睫状体周围液渗透压的功能。与ENaC相反，囊性纤维化跨膜传导调节因子（CFTR）将氯离子从细胞质引导至管腔，其主要位于顶侧，但不位于纤毛上。ENaC的纤毛定位需要重新评估CFTR和其他ENaC功能调节剂的作用机制。运动纤毛上的ENaC对于运动纤毛的多种功能，如生殖细胞运输、受精、植入、呼吸道的清除和细胞迁移是必不可少的。
Epithelial sodium channels (ENaCs) are located on the apical surface of cells and funnel Na+ ions from the lumen into the cell. ENaC function also regulates extracellular fluid volume as water flows across membranes accompanying Na+ ions to maintain osmolarity. To examine the sites of expression and intracellular localization of ENaC, we generated polyclonal antibodies against the extracellular domain of human alpha-ENaC subunit that we expressed in E. coli. Three-dimensional (3D) confocal microscopy of immunofluorescence using these antibodies for the first time revealed that ENaCs are uniformly distributed on the ciliary surface in all epithelial cells with motile cilia lining the bronchus in human lung and female reproductive tract, all along the fimbrial end of the fallopian tube, the ampulla and rare cells in the uterine glands. Quantitative analysis indicated that cilia increase cell surface area > 70-fold and the amount of ENaC on cilia is > 1,000-fold higher than on non-ciliated cell surface. These findings indicate that ENaC functions as a regulator of the osmolarity of the periciliary fluid bathing the cilia. In contrast to ENaC, cystic fibrosis transmembrane conductance regulator (CFTR) that channels chloride ions from the cytoplasm to the lumen is located mainly on the apical side, but not on cilia. The cilial localization of ENaC requires reevaluation of the mechanisms of action of CFTR and other modulators of ENaC function. ENaC on motile cilia should be essential for diverse functions of motile cilia, such as germ cell transport, fertilization, implantation, clearance of respiratory airways and cell migration.