title: Intercalated Cell Depletion and Vacuolar H+-ATPase Mistargeting in an Ae1 R607H Knockin Model.
abstract: Distal nephron acid secretion is mediated by highly specialized type A intercalated cells (A-ICs), which contain vacuolar H+-ATPase (V-type ATPase)-rich vesicles that fuse with the apical plasma membrane on demand. Intracellular bicarbonate generated by luminal H+secretion is removed by the basolateral anion-exchanger AE1. Chronically reduced renal acid excretion in distal renal tubular acidosis (dRTA) may lead to nephrocalcinosis and renal failure. Studies in MDCK monolayers led to the proposal of a dominant-negative trafficking mechanism to explain AE1-associated dominant dRTA. To test this hypothesisin vivo, we generated an Ae1 R607H knockin mouse, which corresponds to the most common dominant dRTA mutation in human AE1, R589H. Compared with wild-type mice, heterozygous and homozygous R607H knockin mice displayed incomplete dRTA characterized by compensatory upregulation of the Na+/HCO3-cotransporter NBCn1. Red blood cell Ae1-mediated anion-exchange activity and surface polypeptide expression did not change. Mutant mice expressed far less Ae1 in A-ICs, but basolateral targeting of the mutant protein was preserved. Notably, mutant mice also exhibited reduced expression of V-type ATPase and compromised targeting of this proton pump to the plasma membrane upon acid challenge. Accumulation of p62- and ubiquitin-positive material in A-ICs of knockin mice suggested a defect in the degradative pathway, which may explain the observed loss of A-ICs. R607H knockin did not affect type B intercalated cells. We propose that reduced basolateral anion-exchange activity in A-ICs inhibits trafficking and regulation of V-type ATPase, compromising luminal H+secretion and possibly lysosomal acidification.
authors.affiliation: Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
authors.forename: Rizwan
authors.initials: R
authors.lastname: Mumtaz
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris Descartes University, Department of Physiology, Hôpital Européen Georges Pompidou, Paris, France.|Department of Cardio-Thoracic and Respiratory Science, Second University of Naples, Naples, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Trepiccione
authors.affiliation: Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Hennings
authors.affiliation: Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
authors.forename: Antje K
authors.initials: AK
authors.lastname: Huebner
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris Descartes University, Department of Physiology, Hôpital Européen Georges Pompidou, Paris, France.
authors.forename: Bettina
authors.initials: B
authors.lastname: Serbin
authors.affiliation: Centre National de la Recherche Scientifique, Équipe de Recherche Labellisée 8228, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche en Santé 1138, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Picard
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: A K M Shahid
authors.initials: AKMS
authors.lastname: Ullah
authors.affiliation: Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and.
authors.forename: Teodor G
authors.initials: TG
authors.lastname: Păunescu
authors.affiliation: Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and.
authors.forename: Diane E
authors.initials: DE
authors.lastname: Capen
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Rawad M
authors.initials: RM
authors.lastname: Lashhab
authors.affiliation: Institut National de la Transfusion Sanguine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche en Santé 1134, Laboratory of Excellence Globule Rouge-Excellence, Paris Diderot University, Paris, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mouro-Chanteloup
authors.affiliation: Nephrology Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts.
authors.forename: Seth L
authors.initials: SL
authors.lastname: Alper
authors.affiliation: Institute of Physiology, University of Zurich, Zurich, Switzerland; and.
authors.forename: Carsten A
authors.initials: CA
authors.lastname: Wagner
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cordat
authors.affiliation: Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and.
authors.forename: Dennis
authors.initials: D
authors.lastname: Brown
authors.affiliation: Service de Physiologie Explorations Fonctionnelles Rénales, Centre Hospitalier Universitaire de la Réunion, Hôpital Felix Guyon; and dominique.eladari@inserm.fr christian.huebner@med.uni-jena.de.|Institut National de la Santé et de la Recherche Médicale U1188 Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI), Saint Denis, La Réunion, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Eladari
authors.affiliation: Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany; dominique.eladari@inserm.fr christian.huebner@med.uni-jena.de.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Hübner
mesh_terms: D000141:Acidosis, Renal Tubular / Q000201:enzymology*; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology* / Q000201:enzymology*; D008297:Male; D051379:Mice; D008954:Models, Biological; D025262:Vacuolar Proton-Translocating ATPases / Q000502:physiology*
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D025262:Vacuolar Proton-Translocating ATPases
keywords: Cell & Transport Physiology; chronic metabolic acidosis; distal tubule; genetic renal disease; ion transport; transgenic mouse