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Sci Rep. 2018 Feb 19;8(1):3249. doi: 10.1038/s41598-018-21405-x.

Consequences of SPAK inactivation on Hyperkalemic Hypertension caused by WNK1 mutations: evidence for differential roles of WNK1 and WNK4.

Rafael C1,2,3,4, Soukaseum C1,2,5, Baudrie V1,2,6, Frère P3,4, Hadchouel J7,8,9,10.

Author information

1
Institut National de la Santé et de la Recherche Médicale (INSERM), Unit 970, Paris Cardiovascular Research Center, Paris, France.
2
Universités Paris-Descartes et Paris-Diderot, Sorbonne Paris Cité, Paris, France.
3
Sorbonne Université, Paris, France.
4
INSERM UMR_S1155, Tenon Hospital, Paris, France.
5
INSERM UMR_S1176, CHU de Bicêtre, Le Kremlin-Bicêtre, France.
6
Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France.
7
Institut National de la Santé et de la Recherche Médicale (INSERM), Unit 970, Paris Cardiovascular Research Center, Paris, France. juliette.hadchouel@inserm.fr.
8
Universités Paris-Descartes et Paris-Diderot, Sorbonne Paris Cité, Paris, France. juliette.hadchouel@inserm.fr.
9
Sorbonne Université, Paris, France. juliette.hadchouel@inserm.fr.
10
INSERM UMR_S1155, Tenon Hospital, Paris, France. juliette.hadchouel@inserm.fr.

Abstract

Mutations of the gene encoding WNK1 [With No lysine (K) kinase 1] or WNK4 cause Familial Hyperkalemic Hypertension (FHHt). Previous studies have shown that the activation of SPAK (Ste20-related Proline/Alanine-rich Kinase) plays a dominant role in the development of FHHt caused by WNK4 mutations. The implication of SPAK in FHHt caused by WNK1 mutation has never been investigated. To clarify this issue, we crossed WNK1+/FHHt mice with SPAK knock-in mice in which the T-loop Thr243 residue was mutated to alanine to prevent activation by WNK kinases. We show that WNK1+/FHHT:SPAK 243A/243A mice display an intermediate phenotype, between that of control and SPAK 243A/243A mice, with normal blood pressure but hypochloremic metabolic alkalosis. NCC abundance and phosphorylation levels also decrease below the wild-type level in the double-mutant mice but remain higher than in SPAK 243A/243A mice. This is different from what was observed in WNK4-FHHt mice in which SPAK inactivation completely restored the phenotype and NCC expression to wild-type levels. Although these results confirm that FHHt caused by WNK1 mutations is dependent on the activation of SPAK, they suggest that WNK1 and WNK4 play different roles in the distal nephron.

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