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XB-ART-56115
Am J Physiol Renal Physiol 2018 Sep 01;3153:F734-F745. doi: 10.1152/ajprenal.00145.2018.
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Kidney-specific WNK1 isoform (KS-WNK1) is a potent activator of WNK4 and NCC.

Argaiz ER , Chavez-Canales M , Ostrosky-Frid M , Rodríguez-Gama A , Vázquez N , Gonzalez-Rodriguez X , Garcia-Valdes J , Hadchouel J , Ellison D , Gamba G .


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Familial hyperkalemic hypertension (FHHt) can be mainly attributed to increased activity of the renal Na+:Cl- cotransporter (NCC), which is caused by altered expression and regulation of the with-no-lysine (K) 1 (WNK1) or WNK4 kinases. The WNK1 gene gives rise to a kidney-specific isoform that lacks the kinase domain (KS-WNK1), the expression of which occurs primarily in the distal convoluted tubule. The role played by KS-WNK1 in the modulation of the WNK/STE20-proline-alanine rich kinase (SPAK)/NCC pathway remains elusive. In the present study, we assessed the effect of human KS-WNK1 on NCC activity and on the WNK4-SPAK pathway. Microinjection of oocytes with human KS-WNK1 cRNA induces remarkable activation and phosphorylation of SPAK and NCC. The effect of KS-WNK1 was abrogated by eliminating a WNK-WNK-interacting domain and by a specific WNK inhibitor, WNK463, indicating that the activation of SPAK/NCC by KS-WNK1 is due to interaction with another WNK kinase. Under control conditions in oocytes, the activating serine 335 of the WNK4 T loop is not phosphorylated. In contrast, this serine becomes phosphorylated when the intracellular chloride concentration ([Cl-]i) is reduced or when KS-WNK1 is coexpressed with WNK4. KS-WNK1-mediated activation of WNK4 is not due to a decrease of the [Cl-]i. Coimmunoprecipitation analysis revealed that KS-WNK1 and WNK4 interact with each other and that WNK4 becomes autophosphorylated at serine 335 when it is associated with KS-WNK1. Together, these observations suggest that WNK4 becomes active in the presence of KS-WNK1, despite a constant [Cl-]i.

???displayArticle.pubmedLink??? 29846116
???displayArticle.pmcLink??? PMC6172580
???displayArticle.link??? Am J Physiol Renal Physiol
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Species referenced: Xenopus laevis
Genes referenced: slc12a3 stk39 wnk1 wnk4
GO keywords: sodium ion transport [+]

???displayArticle.disOnts??? renal tubular transport disease [+]
???displayArticle.omims??? PSEUDOHYPOALDOSTERONISM, TYPE IIA; PHA2A
References [+] :
Bazúa-Valenti, The Effect of WNK4 on the Na+-Cl- Cotransporter Is Modulated by Intracellular Chloride. 2015, Pubmed, Xenbase