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Downregulation of NCC and NKCC2 cotransporters by kidney-specific WNK1 revealed by gene disruption and transgenic mouse models.

WNK1 (with-no-lysine[K]-1) is a protein kinase of which mutations cause a familial hypertension and hyperkalemia syndrome known as pseudohypoaldosteronism type 2 (PHA2). Kidney-specific (KS) WNK1 is an alternatively spliced form of WNK1 kinase missing most of the kinase domain. KS-WNK1 downregulates the Na(+)-Cl(-) cotransporter NCC by antagonizing the effect of full-length WNK1 when expressed in Xenopus oocytes. The physiological role of KS-WNK1 in the regulation of NCC and potentially other Na(+) transporters in vivo is unknown. Here, we report that mice overexpressing KS-WNK1 in the kidney exhibited renal Na(+) wasting, elevated plasma levels of angiotensin II and aldosterone yet lower blood pressure relative to wild-type littermates. Immunofluorescent staining revealed reduced surface expression of total and phosphorylated NCC and the Na(+)-K(+)-2Cl(-) cotransporter NKCC2 in the distal convoluted tubule and the thick ascending limb of Henle's loop, respectively. Conversely, mice with targeted deletion of exon 4A (the first exon for KS-WNK1) exhibited Na(+) retention, elevated blood pressure on a high-Na(+) diet and increased surface expression of total and phosphorylated NCC and NKCC2 in respective nephron segments. Thus, KS-WNK1 is a negative regulator of NCC and NKCC2 in vivo and plays an important role in the control of Na(+) homeostasis and blood pressure. These results have important implications to the pathogenesis of PHA2 with WNK1 mutations.

Pubmed ID: 21131289

Authors

  • Liu Z
  • Xie J
  • Wu T
  • Truong T
  • Auchus RJ
  • Huang CL

Journal

Human molecular genetics

Publication Data

March 1, 2011

Associated Grants

  • Agency: NIDDK NIH HHS, Id: DK-59530
  • Agency: NIDDK NIH HHS, Id: P30DK079328

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Blood Pressure
  • Disease Models, Animal
  • Down-Regulation
  • Female
  • Gene Expression Regulation
  • Gene Silencing
  • Humans
  • Kidney
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Molecular Sequence Data
  • Organ Specificity
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases
  • Pseudohypoaldosteronism
  • Receptors, Drug
  • Sodium
  • Sodium-Potassium-Chloride Symporters
  • Solute Carrier Family 12, Member 1
  • Solute Carrier Family 12, Member 3
  • Symporters