DISTRIBUTION OF THE AQUAPORIN CHIP IN SECRETORY AND RESORPTIVE EPITHELIA AND CAPILLARY ENDOTHELIA
DISTRIBUTION OF THE AQUAPORIN CHIP IN SECRETORY AND RESORPTIVE EPITHELIA AND CAPILLARY ENDOTHELIA
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DOI：
10.1073/pnas.90.15.7275
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发表时间：
1993-08-01
影响因子：
11.1
通讯作者：
AGRE, P
中科院分区：
文献类型：
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作者：
NIELSEN, S;SMITH, BL;AGRE, P
水选择通道的存在被认为可以解释红细胞和某些上皮细胞的高透水性。水通道蛋白CHIP(28 kDa的通道形成完整膜蛋白)是一种分子水通道，在红细胞和肾单位透水段中含量丰富。用亲和纯化的抗CHIP抗体对多器官膜进行免疫印迹、免疫组织化学和免疫电子显微镜观察，以确定CHIP是否可能介导其他水通性上皮细胞的跨膜水运动。脉络丛上皮顶膜浓染，提示CHIP在脑脊液分泌中起作用。在眼内，睫状上皮顶端和基外区、房水分泌部位、晶状体上皮和角膜内皮细胞中均含有大量的CHIP。在肝胆管膜和胆囊水吸收上皮中检测到CHIP，提示CHIP参与了胆汁的分泌和浓缩。在乳腺、唾液或泪腺的腺上皮中未检测到CHIP，提示存在其他水通道亚型。在胃肠粘膜上皮细胞中也未检测到CHIP。在包括心肌和骨骼肌在内的不同组织中，肠道乳酸膜和连续毛细血管中含有丰富的芯片，从而为某些淋巴管和毛细血管床的已知水渗透性提供了分子解释。这些研究强调了这样一种假设，即CHIP在整个身体的跨细胞水分运动中发挥着重要作用。
The existence of water-selective channels has been postulated to explain the high water permeability of erythrocytes and certain epithelial cells. The aquaporin CHIP (channel-forming integral membrane protein of 28 kDa), a molecular water channel, is abundant in erythrocytes and water-permeable segments of the nephron. To determine whether CHIP may mediate transmembrane water movement in other water-permeable epithelia, membranes of multiple organs were studied by immunoblotting, immunohistochemistry, and immunoelectron microscopy using affinity-purified anti-CHIP IgG. The apical membrane of the choroid plexus epithelium was densely stained, implying a role for CHIP in the secretion of cerebrospinal fluid. In the eye, CHIP was abundant in apical and basolateral domains of ciliary epithelium, the site of aqueous humor secretion, and also in lens epithelium and corneal endothelium. CHIP was detected in membranes of hepatic bile ducts and water-resorptive epithelium of gall bladder, suggesting a role in bile secretion and concentration. CHIP was not detected in glandular epithelium of mammary, salivary, or lacrimal glands, suggesting the existence of other water-channel isoforms. CHIP was also not detected within the epithelium of the gastrointestinal mucosa. CHIP was abundant in membranes of intestinal lacteals and continuous capillaries in diverse tissues, including cardiac and skeletal muscle, thus providing a molecular explanation for the known water permeability of certain lymphatics and capillary beds. These studies underscore the hypothesis that CHIP plays a major role in transcellular water movement throughout the body.