WNK3 positively regulates epithelial calcium channels TRPV5 and TRPV6 via a kinase-dependent pathway

Am J Physiol Renal Physiol. 2008 Nov;295(5):F1472-84. doi: 10.1152/ajprenal.90229.2008. Epub 2008 Sep 3.

Abstract

WNK3, a member of the With No Lysine (K) family of protein serine/threonine kinases, was shown to regulate members of the SLC12A family of cation-chloride cotransporters and the renal outer medullary K+ channel ROMK and Cl(-) channel SLC26A9. To evaluate the effect of WNK3 on TRPV5, a renal epithelial Ca2+ channel that serves as a gatekeeper for active Ca2+ reabsorption, WNK3 and TRPV5 were coexpressed in Xenopus laevis oocytes and the function and expression of TRPV5 were subsequently examined. An 82.7 +/- 7.1% increase in TRPV5-mediated Ca2+ uptake was observed when WNK3 was coexpressed. A similar increase in TRPV5-mediated Na+ current was observed with the voltage-clamp technique. WNK3 also enhanced Ca2+ influx and Na+ current mediated by TRPV6, which is the closest homolog of TRPV5 that mediates active intestinal Ca2+ absorption. The kinase domain of WNK3 alone was sufficient to increase TRPV5-mediated Ca2+ transport, and the positive regulatory effect was abolished by the kinase-inactive D294A mutation in WNK3, indicating a kinase-dependent mechanism. The complexly glycosylated TRPV5 that appears at the plasma membrane was increased by WNK3. The exocytosis of TRPV5 was increased by WNK3, and the effect of WNK3 on TRPV5 was abolished by the microtubule inhibitor colchicine. The increased plasma membrane expression of TRPV5 was likely due to the enhanced delivery of mature TRPV5 to the plasma membrane from its intracellular pool via the secretory pathway. These results indicate that WNK3 is a positive regulator of the transcellular Ca2+ transport pathway.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Calcium / metabolism
  • Calcium Channels / genetics
  • Calcium Channels / physiology*
  • Cell Size
  • Colchicine / pharmacology
  • Cytochalasin D / pharmacology
  • Electrophysiology
  • Exocytosis / drug effects
  • Exocytosis / physiology
  • Female
  • Glycosylation
  • Humans
  • Membrane Potentials / drug effects
  • Oocytes / cytology
  • Oocytes / metabolism
  • Oocytes / physiology
  • Phosphotransferases / genetics
  • Phosphotransferases / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Protein Transport / drug effects
  • Protein Transport / physiology
  • Sequence Deletion
  • Sodium / metabolism
  • Sodium Chloride Symporters / genetics
  • Sodium Chloride Symporters / physiology
  • TRPV Cation Channels / genetics
  • TRPV Cation Channels / physiology*
  • Xenopus laevis

Substances

  • Calcium Channels
  • Sodium Chloride Symporters
  • TRPV Cation Channels
  • TRPV5 protein, human
  • TRPV6 protein, human
  • Cytochalasin D
  • Sodium
  • Phosphotransferases
  • Protein Serine-Threonine Kinases
  • WNK3 protein, human
  • WNK4 protein, human
  • Colchicine
  • Calcium