The effect of WNK4 on the Na+-Cl- cotransporter is modulated by intracellular chloride

Silvana Bazúa-Valenti, María Chávez-Canales, Lorena Rojas-Vega, Xochiquetzal González-Rodríguez, Norma Vázquez, Alejandro Rodríguez-Gama, Eduardo R. Argaiz, Zesergio Melo, Consuelo Plata, David H. Ellison, Jesús García-Valdés, Juliette Hadchouel, Gerardo Gamba

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70 Scopus citations

Abstract

It is widely recognized that the phenotype of familial hyperkalemic hypertension is mainly a consequence of increased activity of the renal Na+-Cl- cotransporter (NCC) because of altered regulation by with no-lysinekinase 1 (WNK1) or WNK4. The effect ofWNK4 on NCC, however, has been controversial because both inhibition and activation have been reported. It has been recently shown that the long isoform of WNK1 (L-WNK1) is a chloride-sensitive kinase activated by a low Clconcentration. Therefore, we hypothesized that WNK4 effects on NCC could be modulated by intracellular chloride concentration ([Cl-]i), and we tested this hypothesis in oocytes injected with NCC cRNA with or without WNK4 cRNA. At baseline in oocytes, [Cl-]i was near 50 mM, autophosphorylation of WNK4 was undetectable, andNCC activity was either decreased or unaffected byWNK4. A reduction of [Cl-]i, either by low chloride hypotonic stress or coinjection of oocytes with the solute carrier family 26 (anion exchanger)-member 9 (SLC26A9) cRNA, promoted WNK4 autophosphorylation and increased NCC-dependent Na+ transport in a WNK4-dependent manner. Substitution of the leucine with phenylalanine at residue 322 ofWNK4, homologous to the chloride-binding pocket in L-WNK1, convertedWNK4 into a constitutively autophosphorylated kinase that activated NCC, even without chloride depletion. Elimination of the catalytic activity (D321A or D321K-K186D) or the autophosphorylation site (S335A) in mutant WNK4-L322F abrogated the positive effect on NCC. These observations suggest that WNK4 can exert differential effects on NCC, depending on the intracellular chloride concentration.

Original languageEnglish (US)
Pages (from-to)1781-1786
Number of pages6
JournalJournal of the American Society of Nephrology
Volume26
Issue number8
DOIs
StatePublished - Aug 1 2015

ASJC Scopus subject areas

  • Nephrology

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    Bazúa-Valenti, S., Chávez-Canales, M., Rojas-Vega, L., González-Rodríguez, X., Vázquez, N., Rodríguez-Gama, A., Argaiz, E. R., Melo, Z., Plata, C., Ellison, D. H., García-Valdés, J., Hadchouel, J., & Gamba, G. (2015). The effect of WNK4 on the Na+-Cl- cotransporter is modulated by intracellular chloride. Journal of the American Society of Nephrology, 26(8), 1781-1786. https://doi.org/10.1681/ASN.2014050470