Multiple molecular mechanisms are involved in the activation of the kidney sodium-chloride cotransporter by hypokalemia

Adrián R. Murillo-de-Ozores, Héctor Carbajal-Contreras, Germán R. Magaña-Ávila, Raquel Valdés, Leoneli I. Grajeda-Medina, Norma Vázquez, Teresa Zariñán, Alejandro López-Saavedra, Avika Sharma, Dao Hong Lin, Wen Hui Wang, Eric Delpire, David H. Ellison, Gerardo Gamba, María Castañeda-Bueno

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Low potassium intake activates the kidney sodium-chloride cotransporter (NCC) whose phosphorylation and activity depend on the With-No-Lysine kinase 4 (WNK4) that is inhibited by chloride binding to its kinase domain. Low extracellular potassium activates NCC by decreasing intracellular chloride thereby promoting chloride dissociation from WNK4 where residue L319 of WNK4 participates in chloride coordination. Since the WNK4-L319F mutant is constitutively active and chloride-insensitive in vitro, we generated mice harboring this mutation that displayed slightly increased phosphorylated NCC and mild hyperkalemia when on a 129/sv genetic background. On a low potassium diet, upregulation of phosphorylated NCC was observed, suggesting that in addition to chloride sensing by WNK4, other mechanisms participate which may include modulation of WNK4 activity and degradation by phosphorylation of the RRxS motif in regulatory domains present in WNK4 and KLHL3, respectively. Increased levels of WNK4 and kidney-specific WNK1 and phospho-WNK4-RRxS were observed in wild-type and WNK4L319F/L319F mice on a low potassium diet. Decreased extracellular potassium promoted WNK4-RRxS phosphorylation in vitro and ex vivo as well. These effects might be secondary to intracellular chloride depletion, as reduction of intracellular chloride in HEK293 cells increased phospho-WNK4-RRxS. Phospho-WNK4-RRxS levels were increased in mice lacking the Kir5.1 potassium channel, which presumably have decreased distal convoluted tubule intracellular chloride. Similarly, phospho-KLHL3 was modulated by changes in intracellular chloride in HEK293 cells. Thus, our data suggest that multiple chloride-regulated mechanisms are responsible for NCC upregulation by low extracellular potassium.

Original languageEnglish (US)
Pages (from-to)1030-1041
Number of pages12
JournalKidney International
Volume102
Issue number5
DOIs
StatePublished - Nov 2022

Keywords

  • blood pressure
  • distal convoluted tubule
  • epithelial transport
  • familial hyperkalemic hypertension
  • Gitelman syndrome
  • potassium

ASJC Scopus subject areas

  • Nephrology

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