TY - JOUR
T1 - The effect of WNK4 on the Na+-Cl- cotransporter is modulated by intracellular chloride
AU - Bazúa-Valenti, Silvana
AU - Chávez-Canales, María
AU - Rojas-Vega, Lorena
AU - González-Rodríguez, Xochiquetzal
AU - Vázquez, Norma
AU - Rodríguez-Gama, Alejandro
AU - Argaiz, Eduardo R.
AU - Melo, Zesergio
AU - Plata, Consuelo
AU - Ellison, David H.
AU - García-Valdés, Jesús
AU - Hadchouel, Juliette
AU - Gamba, Gerardo
N1 - Publisher Copyright:
© 2015 by the American Society of Nephrology.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - 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.
AB - 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.
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U2 - 10.1681/ASN.2014050470
DO - 10.1681/ASN.2014050470
M3 - Article
C2 - 25542968
AN - SCOPUS:84938943434
SN - 1046-6673
VL - 26
SP - 1781
EP - 1786
JO - Journal of the American Society of Nephrology
JF - Journal of the American Society of Nephrology
IS - 8
ER -