title: The Effect of WNK4 on the Na+-Cl- Cotransporter Is Modulated by Intracellular Chloride.
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-lysine-kinase 1 (WNK1) or WNK4. The effect of WNK4 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 Cl(-) concentration. 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, and NCC activity was either decreased or unaffected by WNK4. 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 of WNK4, homologous to the chloride-binding pocket in L-WNK1, converted WNK4 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.
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Silvana
authors.initials: S
authors.lastname: Bazúa-Valenti
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: María
authors.initials: M
authors.lastname: Chávez-Canales
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Lorena
authors.initials: L
authors.lastname: Rojas-Vega
authors.affiliation: Analytical Chemistry Department, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico;
authors.forename: Xochiquetzal
authors.initials: X
authors.lastname: González-Rodríguez
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Norma
authors.initials: N
authors.lastname: Vázquez
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rodríguez-Gama
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Eduardo R
authors.initials: ER
authors.lastname: Argaiz
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Zesergio
authors.initials: Z
authors.lastname: Melo
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico;
authors.forename: Consuelo
authors.initials: C
authors.lastname: Plata
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, OR;
authors.forename: David H
authors.initials: DH
authors.lastname: Ellison
authors.affiliation: Analytical Chemistry Department, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico;
authors.forename: Jesús
authors.initials: J
authors.lastname: García-Valdés
authors.affiliation: INSERM UMR970, Paris Cardiovascular Research Center, Paris, France; and Faculty of Medicine, University Paris-Descartes, Sorbonne Paris City, Paris, France.
authors.forename: Juliette
authors.initials: J
authors.lastname: Hadchouel
authors.affiliation: Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico; gamba@biomedicas.unam.mx.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Gamba
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism*; D006801:Humans; D051379:Mice; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D049992:Sodium Chloride Symporters / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D002712:Chlorides; D049992:Sodium Chloride Symporters; D029867:Xenopus Proteins; D017346:Protein Serine-Threonine Kinases; C519693:WNK4 protein, Xenopus
keywords: distal tubule; diuretics; hypertension; ion transport