Cell-specific regulation of L-WNK1 by dietary K+

Academic Article

Abstract

  • © 2016 the American Physiological Society. Flow-induced K+ secretion in the aldosterone-sensitive distal nephron is mediated by high-conductance Ca2+-activated K+ (BK) channels. Familial hyperkalemic hypertension (pseudohypoaldosteronism type II) is an inherited form of hypertension with decreased K+ secretion and increased Na+ reabsorption. This disorder is linked to mutations in genes encoding with-no-lysine kinase 1 (WNK1), WNK4, and Kelch-like 3/Cullin 3, two components of an E3 ubiquitin ligase complex that degrades WNKs. We examined whether the full-length (or “long”) form of WNK1 (L-WNK1) affected the expression of BK α-subunits in HEK cells. Overexpression of L-WNK1 promoted a significant increase in BK α-subunit whole cell abundance and functional channel expression. BK α-subunit abundance also increased with coexpression of a kinase dead L-WNK1 mutant (K233M) and with kidney-specific WNK1 (KS-WNK1), suggesting that the catalytic activity of L-WNK1 was not required to increase BK expression. We examined whether dietary K+ intake affected L-WNK1 expression in the aldosterone-sensitive distal nephron. We found a paucity of L-WNK1 labeling in cortical collecting ducts (CCDs) from rabbits on a low-K+ diet but observed robust staining for L-WNK1 primarily in intercalated cells when rabbits were fed a high-K+ diet. Our results and previous findings suggest that L-WNK1 exerts different effects on renal K+ secretory channels, inhibiting renal outer medullary K+ channels and activating BK channels. A high-K+ diet induced an increase in L-WNK1 expression selectively in intercalated cells and may contribute to enhanced BK channel expression and K+ secretion in CCDs.
  • Author List

  • Webb TN; Carrisoza-Gaytan R; Montalbetti N; Rued A; Roy A; Socovich AM; Subramanya AR; Satlin LM; Kleyman TR; Carattino MD
  • Start Page

  • F15
  • End Page

  • F26
  • Volume

  • 310