title: Alternative splice variant of the thiazide-sensitive NaCl cotransporter: a novel player in renal salt handling.
abstract: The thiazide-sensitive NaCl cotransporter (NCC) is an important pharmacological target in the treatment of hypertension. The human SLC12A3 gene, encoding NCC, gives rise to three isoforms. Only the third isoform has been extensively investigated. The aim of the present study was, therefore, to establish the abundance and localization of the almost identical isoforms 1 and 2 (NCC1/2) in the human kidney and to determine their functional properties and regulation in physiological conditions. Immunohistochemical analysis of NCC1/2 in the human kidney revealed that NCC1/2 localizes to the apical plasma membrane of the distal convoluted tubule. Importantly, NCC1/2 mRNA constitutes ∼ 44% of all NCC isoforms in the human kidney. Functional analysis performed in the Xenopus laevis oocyte revealed that thiazide-sensitive (22)Na(+) transport of NCC1 was significantly increased compared with NCC3. Mimicking a constitutively active phosphorylation site at residue 811 (S811D) in NCC1 further augmented Na(+) transport, while a nonphosphorylatable variant (S811A) of NCC1 prevented this enhanced response. Analysis of human urinary exosomes demonstrated that water loading in human subjects significantly reduces the abundance of NCC1/2 in urinary exosomes. The present study highlights that previously underrepresented NCC1/2 is a fully functional thiazide-sensitive NaCl-transporting protein. Being significantly expressed in the kidney, it may constitute a unique route of renal NaCl reabsorption and could, therefore, play an important role in blood pressure regulation.
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Omar A Z
authors.initials: OA
authors.lastname: Tutakhel
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Sabina
authors.initials: S
authors.lastname: Jeleń
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Marco
authors.initials: M
authors.lastname: Valdez-Flores
authors.affiliation: Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark;
authors.forename: Henrik
authors.initials: H
authors.lastname: Dimke
authors.affiliation: OncoProteomics Laboratory, Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Sander R
authors.initials: SR
authors.lastname: Piersma
authors.affiliation: OncoProteomics Laboratory, Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Connie R
authors.initials: CR
authors.lastname: Jimenez
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Jaap
authors.initials: J
authors.lastname: Deinum
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Medicine III, University Hospital Carl Gustav Carus, Technische Universität, Dresden, Germany; and.
authors.forename: Jacques W
authors.initials: JW
authors.lastname: Lenders
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Joost G J
authors.initials: JG
authors.lastname: Hoenderop
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands; rene.bindels@radboudumc.nl.
authors.forename: René J M
authors.initials: RJ
authors.lastname: Bindels
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D004326:Drinking; D055354:Exosomes / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D020033:Protein Isoforms; D040901:Proteomics / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D065608:Renal Reabsorption; D012965:Sodium Chloride / Q000378:metabolism*; D064486:Solute Carrier Family 12, Member 3 / Q000235:genetics / Q000378:metabolism / Q000652:urine; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D014162:Transfection; D014982:Xenopus laevis
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; C578874:SLC12A3 protein, human; D064486:Solute Carrier Family 12, Member 3; D012965:Sodium Chloride
keywords: WNK4; aldosterone-sensitive distal part of the nephron; hypertension; kidney; sodium