title: WNK1 regulates phosphorylation of cation-chloride-coupled cotransporters via the STE20-related kinases, SPAK and OSR1.
abstract: The WNK1 and WNK4 genes have been found to be mutated in some patients with hyperkalemia and hypertension caused by pseudohypoaldosteronism type II. The clue to the pathophysiology of pseudohypoaldosteronism type II was its striking therapeutic response to thiazide diuretics, which are known to block the sodium chloride cotransporter (NCC). Although this suggests a role for WNK1 in hypertension, the precise molecular mechanisms are largely unknown. Here we have shown that WNK1 phosphorylates and regulates the STE20-related kinases, Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress response 1 (OSR1). WNK1 was observed to phosphorylate the evolutionary conserved serine residue located outside the kinase domains of SPAK and OSR1, and mutation of the OSR1 serine residue caused enhanced OSR1 kinase activity. In addition, hypotonic stress was shown to activate SPAK and OSR1 and induce phosphorylation of the conserved OSR1 serine residue, suggesting that WNK1 may be an activator of the SPAK and OSR1 kinases. Moreover, SPAK and OSR1 were found to directly phosphorylate the N-terminal regulatory regions of cation-chloride-coupled cotransporters including NKCC1, NKCC2, and NCC. Phosphorylation of NCC was induced by hypotonic stress in cells. These results suggested that WNK1 and SPAK/OSR1 mediate the hypotonic stress signaling pathway to the transporters and may provide insights into the mechanisms by which WNK1 regulates ion balance.
authors.affiliation: Department of Molecular Cell Biology, Medical Research Institute and School of Biomedical Science, Tokyo Medical and Dental University, and CREST, JST, Chiyoda, Tokyo 101-0062.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Moriguchi
authors.forename: Seiichi
authors.initials: S
authors.lastname: Urushiyama
authors.forename: Naoki
authors.initials: N
authors.lastname: Hisamoto
authors.forename: Shun-ichiro
authors.initials: S
authors.lastname: Iemura
authors.forename: Shinichi
authors.initials: S
authors.lastname: Uchida
authors.forename: Tohru
authors.initials: T
authors.lastname: Natsume
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shibuya
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002412:Cations / Q000737:chemistry*; D002460:Cell Line; D002712:Chlorides / Q000737:chemistry; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004232:Diuretics / Q000494:pharmacology; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism; D019143:Evolution, Molecular; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000473:pathology; D015151:Immunoblotting; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins; D007477:Ions; D013058:Mass Spectrometry; D051379:Mice; D015778:Minor Histocompatibility Antigens; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000502:physiology*; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques; D000076204:WNK Lysine-Deficient Protein Kinase 1; D000099317:Hippo Kinases
chemical_list: D002412:Cations; D002712:Chlorides; D004232:Diuretics; D005982:Glutathione Transferase; D047908:Intracellular Signaling Peptides and Proteins; D007477:Ions; D015778:Minor Histocompatibility Antigens; D009419:Nerve Tissue Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins; D012694:Serine; D000076204:WNK Lysine-Deficient Protein Kinase 1; C118135:OXSR1 protein, human; C109163:STK24 protein, human; D000099317:Hippo Kinases; C506604:Oxsr1 protein, rat; C486409:STK39 protein, human; C498743:WNK1 protein, human