title: Cloning and expression of apical membrane water channel of rat kidney collecting tubule.
abstract: 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.
authors.affiliation: Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Fushimi
authors.forename: S
authors.initials: S
authors.lastname: Uchida
authors.forename: Y
authors.initials: Y
authors.lastname: Hara
authors.forename: Y
authors.initials: Y
authors.lastname: Hirata
authors.forename: F
authors.initials: F
authors.lastname: Marumo
authors.forename: S
authors.initials: S
authors.lastname: Sasaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051398:Aquaporin 1; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D015152:Blotting, Northern; D003001:Cloning, Molecular; D015870:Gene Expression; D007150:Immunohistochemistry; D007685:Kidney Tubules, Collecting / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009865:Oocytes; D010539:Permeability; D016133:Polymerase Chain Reaction; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014981:Xenopus
chemical_list: C496022:Aqp1 protein, rat; C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D008565:Membrane Proteins; D051398:Aquaporin 1