Regulation of the NKCC2 ion cotransporter by SPAK-OSR1-dependent and -independent pathways

Ciaran Richardson, Kei Sakamoto, Paola de los Heros, Maria Deak, David G. Campbell, Alan R. Prescott, Dario R. Alessi

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    Abstract

    Ion cotransporters, such as the Na+/Cl-cotransporter (NCC), control renal salt re-absorption and are regulated by the WNK-signalling pathway, which is over-stimulated in patients suffering from Gordon's hypertension syndrome. Here, we study the regulation of the NKCC2 (SLC12A1) ion cotransporter that contributes towards similar to 25% of renal salt re-absorption and is inhibited by loop-diuretic hypertensive drugs. We demonstrate that hypotonic low-chloride conditions that activate the WNK1-SPAK and OSR1 pathway promote phosphorylation of NKCC2 isoforms (A, B and F) at five residues (Ser91, Thr95, Thr100, Thr105 and Ser130). We establish that the SPAK and OSR1 kinases activated by WNK interact with an RFQV motif on NKCC2 and directly phosphorylate Thr95, Thr100, Thr105 and, possibly, Ser91. Our data indicate that a SPAK-OSR1-independent kinase, perhaps AMP-activated protein kinase (AMPK), phosphorylates Ser130 and that phosphorylation of Thr105 and Ser130 plays the most important roles in stimulating NKCC2 activity. In contrast with NCC, whose membrane translocation is triggered by SPAK-OSR1 phosphorylation, NKCC2 appears to be constitutively at the membrane. Our findings provide new insights into how NKCC2 is regulated and suggest that inhibitors of SPAK and/or OSR1 for the treatment of hypertension would be therapeutically distinct from thiazide or loop diuretics, as they would suppress the activity of both NCC and NKCC2.

    Original languageEnglish
    Pages (from-to)789-800
    Number of pages12
    JournalJournal of Cell Science
    Volume124
    Issue number5
    DOIs
    Publication statusPublished - 1 Mar 2011

    Keywords

    • AMPK
    • Blood pressure
    • NCC
    • NKCC2
    • SPAK-OSR1
    • WNK
    • K-CL COTRANSPORTER
    • ACTIVATED PROTEIN-KINASE
    • PSEUDOHYPOALDOSTERONISM TYPE-II
    • CATION-CHLORIDE COTRANSPORTERS
    • NA+-K+-2CL(-) COTRANSPORTER
    • NA-K-2CL COTRANSPORTER
    • GITELMANS-SYNDROME
    • MOLECULAR PATHOGENESIS
    • HYPOKALEMIC ALKALOSIS
    • BARTTERS-SYNDROME

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