title: SNAP-25-associated Hrs-2 protein colocalizes with AQP2 in rat kidney collecting duct principal cells.
abstract: The vasopressin-induced trafficking of aquaporin-2 (AQP2) water channels in kidney collecting duct is likely mediated by vesicle-targeting proteins (N-ethylmaleimide-sensitive factor attachment protein receptors). Hrs-2 is an ATPase believed to have a modulatory role in regulated exocytosis. To examine whether Hrs-2 is expressed in rat kidney, we carried out RT-PCR combined with DNA sequence analysis and Northern blotting using a digoxigenin-labeled Hrs-2 RNA probe. RT-PCR and Northern blotting revealed that Hrs-2 mRNA is localized in all zones of rat kidney. The presence of Hrs-2 protein in rat kidney was confirmed by immunoblotting, revealing a 115-kDa protein in kidney and brain membrane fractions corresponding to the expected molecular size of Hrs-2. Immunostaining and confocal laser scanning microscopy of LLC-PK(1) cells (a porcine proximal tubule cell line) transfected with Hrs-2 DNA confirmed the specificity of the antibody and revealed that Hrs-2 is mainly localized in intracellular compartments, including cathepsin D-containing lysosomal/endosomal compartments. The cellular and subcellular localization of Hrs-2 in rat kidney was examined by immunocytochemistry and confocal laser scanning microscopy. Hrs-2 immunoreactivity was observed in collecting duct principal cells, and weaker labeling was detected in other nephron segments. The labeling was predominantly present in intracellular vesicles, but labeling was also observed in the apical plasma membrane domains of some cells. Colabeling with AQP2 revealed colocalization in vesicles and apical plasma membrane domains, suggesting a role for Hrs-2 in regulated AQP2 trafficking.
authors.affiliation: Department of Respiratory Diseases, Aarhus University Hospital, DK-8000 Aarhus, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Shukla
authors.forename: H
authors.initials: H
authors.lastname: Hager
authors.forename: T J
authors.initials: TJ
authors.lastname: Corydon
authors.forename: A J
authors.initials: AJ
authors.lastname: Bean
authors.forename: R
authors.initials: R
authors.lastname: Dahl
authors.forename: Z
authors.initials: Z
authors.lastname: Vajda
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: H J
authors.initials: HJ
authors.lastname: Hoffmann
authors.forename: S
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000235:genetics*; D000818:Animals; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000032:analysis / Q000235:genetics*; D002402:Cathepsin D / Q000032:analysis; D002531:Cerebellum / Q000166:cytology / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000502:physiology / Q000648:ultrastructure; D007668:Kidney / Q000166:cytology / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000502:physiology*; D008247:Lysosomes / Q000502:physiology / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics*; D009928:Organ Specificity; D010750:Phosphoproteins; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050825:Synaptosomal-Associated Protein 25
chemical_list: C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D056827:Endosomal Sorting Complexes Required for Transport; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D002402:Cathepsin D; D000251:Adenosine Triphosphatases; C115505:Hgs protein, rat