CELLULAR AND SUBCELLULAR IMMUNOLOCALIZATION OF VASOPRESSIN-REGULATED WATER CHANNEL IN RAT-KIDNEY
CELLULAR AND SUBCELLULAR IMMUNOLOCALIZATION OF VASOPRESSIN-REGULATED WATER CHANNEL IN RAT-KIDNEY
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DOI：
10.1073/pnas.90.24.11663
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发表时间：
1993-12-15
影响因子：
11.1
通讯作者：
HARRIS, HW
中科院分区：
文献类型：
--
作者：
NIELSEN, S;DIGIOVANNI, SR;HARRIS, HW
加压素（抗利尿激素）通过控制肾集合管的水渗透性来调节身体水分平衡。控制机制可能涉及收集管细胞顶端质膜水通道的数量或单位电导的改变。这是如何发生的是未知的，但间接证据存在的“穿梭”假说，该假说指出，加压素导致胞外插入水通道装载囊泡从顶端胞质溶胶。要测试的穿梭假说的关键方面，我们已经准备了多克隆抗血清对最近克隆的集合管水通道蛋白和免疫定位研究（光和电子显微镜水平）中使用的抗血清在薄和冷冻切片从大鼠肾脏。标记只见于集合管主细胞和内髓集合管细胞。顶膜标记强烈。有丰富的小亚尖囊泡和多泡体内的膜结构的重标记。此外，标记的基底外侧质膜内髓集合管。剥夺大鼠的水24或48小时显着增加集合管水通道蛋白表达免疫印迹和免疫标记。这些结果是兼容的至少两种互补模式的水通道调节集合管细胞：（i）控制之间的顶端膜和水库的亚顶端囊泡（穿梭假说）和（ii）调节的绝对水平的水通道蛋白的表达的通道分布。
Vasopressin (antidiuretic hormone) regulates body water balance by controlling water permeability of the renal collecting ducts. The control mechanisms may involve alterations in the number or unit conductance of water channels in the apical plasma membrane of collecting-duct cells. How this occurs is unknown, but indirect evidence exists for the ''shuttle'' hypothesis, which states that vasopressin causes exocytic insertion of water channel-laden vesicles from the apical cytosol. To test key aspects of the shuttle hypothesis, we have prepared polyclonal antisera against the recently cloned collecting-duct water channel protein and used the antisera in immunolocalization studies (light and electron microscopic levels) in thin and ultrathin cryosections from rat kidney. Labeling was seen exclusively in collecting-duct principal cells and inner medullary collecting-duct cells. Apical membrane labeling was intense. There was heavy labeling of abundant small subapical vesicles and of membrane structures within multivesicular bodies. In addition, labeling of basolateral plasma membranes in inner medullary collecting ducts was present. Depriving rats of water for 24 or 48 hr markedly increased collecting-duct water-channel protein expression determined by immunoblotting and immunolabeling. These results are compatible with at least two complementary modes of water-channel regulation in collecting-duct cells: (i) control of channel distribution between the apical membrane and a reservoir in subapical vesicles (shuttle hypothesis) and (ii) regulation of the absolute level of expression of water-channel protein.