Alternative splice variant of the thiazide-sensitive NaCl cotransporter: a novel player in renal salt handling

Am J Physiol Renal Physiol. 2016 Feb 1;310(3):F204-16. doi: 10.1152/ajprenal.00429.2015. Epub 2015 Nov 11.


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.

Keywords: WNK4; aldosterone-sensitive distal part of the nephron; hypertension; kidney; sodium.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Biological Transport
  • Blotting, Western
  • Cell Membrane / metabolism
  • Drinking
  • Exosomes / metabolism
  • Fluorescent Antibody Technique
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Kidney / metabolism*
  • Male
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation
  • Protein Isoforms
  • Proteomics / methods
  • RNA, Messenger / metabolism
  • Renal Reabsorption
  • Sodium Chloride / metabolism*
  • Solute Carrier Family 12, Member 3 / genetics
  • Solute Carrier Family 12, Member 3 / metabolism
  • Solute Carrier Family 12, Member 3 / urine
  • Tandem Mass Spectrometry
  • Time Factors
  • Transfection
  • Xenopus laevis


  • Protein Isoforms
  • RNA, Messenger
  • SLC12A3 protein, human
  • Solute Carrier Family 12, Member 3
  • Sodium Chloride