Fushimi K, Uchida S, Hara Y, Hirata Y, Marumo F, Sasaki S
Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
Nature. 1993 Feb 11;361(6412):549-52. doi: 10.1038/361549a0.
Concentrating urine is mandatory for most mammals to prevent water loss from the body. Concentrated urine is produced in response to vasopressin by the transepithelial recovery of water from the lumen of the kidney collecting tubule through highly water-permeable membranes. In this nephron segment, vasopressin regulates water permeability by endo- and exocytosis of water channels from or to the apical membrane. CHIP28 is a water channel in red blood cells and the kidney proximal tubule, but it is not expressed in the collecting tubule. Here we report the cloning of the complementary DNA for WCH-CD, a water channel of the apical membrane of the kidney collecting tubule. WCH-CD is 42% identical in amino-acid sequence to CHIP28. WCH-CD transcripts are detected only in the collecting tubule of the kidney. Immunohistochemically, WCH-CD is localized to the apical region of the kidney collecting tubule cells. Expression of WCH-CD in Xenopus oocytes markedly increases osmotic water permeability. The functional expression and the limited localization of WCH-CD to the apical region of the kidney collecting tubule suggest that WCH-CD is the vasopressin-regulated water channel.
对大多数哺乳动物来说，浓缩尿液是防止身体水分流失所必需的。浓缩尿液是机体在抗利尿激素作用下，通过高水通透性膜从肾集合管管腔经上皮细胞重吸收水分而产生的。在这个肾单位节段中，抗利尿激素通过水通道从顶端膜内吞和外排来调节水通透性。CHIP28是红细胞和肾近端小管中的一种水通道，但在集合管中不表达。在此我们报道了肾集合管顶端膜水通道WCH-CD互补DNA的克隆。WCH-CD与CHIP28的氨基酸序列有42%的同源性。WCH-CD转录本仅在肾集合管中检测到。免疫组织化学显示，WCH-CD定位于肾集合管细胞的顶端区域。WCH-CD在非洲爪蟾卵母细胞中的表达显著增加了渗透水通透性。WCH-CD在肾集合管顶端区域的功能性表达及其局限性定位表明，WCH-CD是抗利尿激素调节的水通道。
