title: Expression and localization of a UT-B urea transporter in the human bladder.
abstract: Facilitative UT-B urea transporters have been shown to play an important role in the urinary concentrating mechanism. Recent studies have now suggested a link between UT-B allelic variation and human bladder cancer risk. UT-B1 protein has been previously identified in the bladder of various mammalian species, but not yet in humans. The aim of the present study was to investigate whether any UT-B protein was present in the human bladder. First, RT-PCR results confirmed that UT-B1 was strongly expressed at the RNA level in the human bladder, whereas UT-B2 was only weakly present. Initial Western blot analysis confirmed that a novel UT-B COOH-terminal antibody detected human UT-B proteins. Importantly, this antibody detected a specific 40- to 45-kDa UT-B signal in human bladder protein. Using a peptide-N-glycosidase F enzyme, this bladder UT-B signal was deglycosylated to a core 30-kDa protein, which is smaller than the predicted size for UT-B1 but similar to many proteins reported to be UT-B1. Finally, immunolocalization experiments confirmed that UT-B protein was strongly expressed throughout all urothelium layers except for the apical membrane of the outermost umbrella cells. In conclusion, these data confirm the presence of UT-B protein within the human bladder. Further studies are now required to determine the precise nature, regulation, and physiological role of this UT-B.
authors.affiliation: School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: C
authors.initials: C
authors.lastname: Walpole
authors.affiliation: School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: A
authors.initials: A
authors.lastname: Farrell
authors.affiliation: School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: A
authors.initials: A
authors.lastname: McGrane
authors.affiliation: School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin, Ireland gavin.stewart@ucd.ie.
authors.forename: G S
authors.initials: GS
authors.lastname: Stewart
mesh_terms: D006801:Humans; D026901:Membrane Transport Proteins / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001743:Urinary Bladder / Q000378:metabolism*; D019459:Urothelium / Q000378:metabolism; D000096982:Urea Transporters
chemical_list: D026901:Membrane Transport Proteins; D000096982:Urea Transporters
keywords: bladder; protein; urea transporter