TY - JOUR
T1 - WNK bodies cluster WNK4 and SPAK/OSR1 to promote NCC activation in hypokalemia
AU - Thomson, Martin N.
AU - Cuevas, Catherina A.
AU - Bewarder, Tim M.
AU - Dittmayer, Carsten
AU - Miller, Lauren N.
AU - Si, Jinge
AU - Cornelius, Ryan J.
AU - Su, Xiao Tong
AU - Yang, Chao Ling
AU - McCormick, James A.
AU - Hadchouel, Juliette
AU - Ellison, David H.
AU - Bachmann, Sebastian
AU - Mutig, Kerim
N1 - Funding Information:
This work was financially supported by the Deutsche Forschungsgemein-schaft (to S. Bachmann; Grants MU 2924/2-1,2 and BA 700/22-1,2 and INST 335/596-1 FUGG), National Institute of Diabetes and Digestive and Kidney Diseases Grants R01 DK-098141 (to J. A. McCormick), and R01 DK-051496 and R01 DK-054983, Department of Veterans Affairs Grant I01 BX002228, and Transatlantic Network of ExcellenceGrant 17CVD05 from Fondation Leducq (to D. H. Ellison).
Funding Information:
This work was financially supported by the Deutsche Forschungsgemeinschaft (to S. Bachmann; Grants MU 2924/2-1,2 and BA 700/22-1,2 and INST 335/596-1 FUGG), National Institute of Diabetes and Digestive and Kidney Diseases Grants R01 DK-098141 (to J. A. McCormick), and R01 DK-051496 and R01 DK-054983, Department of Veterans Affairs Grant I01 BX002228, and Transatlantic Network of ExcellenceGrant 17CVD05 from Fondation Leducq (to D. H. Ellison).
Publisher Copyright:
© 2020 American Physiological Society. All rights reserved.
PY - 2020
Y1 - 2020
N2 - K+ deficiency stimulates renal salt reuptake via the Na+-Cl– cotransporter (NCC) of the distal convoluted tubule (DCT), thereby reducing K+ losses in downstream nephron segments while increasing NaCl retention and blood pressure. NCC activation is mediated by a kinase cascade involving with no lysine (WNK) kinases upstream of Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1). In K+ deficiency, WNKs and SPAK/OSR1 concentrate in spherical cytoplasmic domains in the DCT termed “WNK bodies,” the significance of which is undetermined. By feeding diets of varying salt and K+ content to mice and using genetically engineered mouse lines, we aimed to clarify whether WNK bodies contribute to WNK-SPAK/OSR1-NCC signaling. Phosphorylated SPAK/OSR1 was present both at the apical membrane and in WNK bodies within 12 h of dietary K+ deprivation, and it was promptly suppressed by K+ loading. In WNK4-deficient mice, however, larger WNK bodies formed, containing unphosphorylated WNK1, SPAK, and OSR1. This suggests that WNK4 is the primary active WNK isoform in WNK bodies and catalyzes SPAK/OSR1 phosphorylation therein. We further examined mice carrying a kidney-specific deletion of the basolateral K+ channel-forming protein Kir4.1, which is required for the DCT to sense plasma K+ concentration. These mice displayed remnant mosaic expression of Kir4.1 in the DCT, and upon K+ deprivation, WNK bodies developed only in Kir4.1-expressing cells. We postulate a model of DCT function in which NCC activity is modulated by plasma K+ concentration via WNK4-SPAK/OSR1 interactions within WNK bodies.
AB - K+ deficiency stimulates renal salt reuptake via the Na+-Cl– cotransporter (NCC) of the distal convoluted tubule (DCT), thereby reducing K+ losses in downstream nephron segments while increasing NaCl retention and blood pressure. NCC activation is mediated by a kinase cascade involving with no lysine (WNK) kinases upstream of Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1). In K+ deficiency, WNKs and SPAK/OSR1 concentrate in spherical cytoplasmic domains in the DCT termed “WNK bodies,” the significance of which is undetermined. By feeding diets of varying salt and K+ content to mice and using genetically engineered mouse lines, we aimed to clarify whether WNK bodies contribute to WNK-SPAK/OSR1-NCC signaling. Phosphorylated SPAK/OSR1 was present both at the apical membrane and in WNK bodies within 12 h of dietary K+ deprivation, and it was promptly suppressed by K+ loading. In WNK4-deficient mice, however, larger WNK bodies formed, containing unphosphorylated WNK1, SPAK, and OSR1. This suggests that WNK4 is the primary active WNK isoform in WNK bodies and catalyzes SPAK/OSR1 phosphorylation therein. We further examined mice carrying a kidney-specific deletion of the basolateral K+ channel-forming protein Kir4.1, which is required for the DCT to sense plasma K+ concentration. These mice displayed remnant mosaic expression of Kir4.1 in the DCT, and upon K+ deprivation, WNK bodies developed only in Kir4.1-expressing cells. We postulate a model of DCT function in which NCC activity is modulated by plasma K+ concentration via WNK4-SPAK/OSR1 interactions within WNK bodies.
KW - Distal convoluted tubule
KW - Kir4.1
KW - Na-Cl cotransporter
KW - Oxidative stress-responsive kinase-1
KW - Ste20-related proline-alanine-rich kinase
KW - WNK bodies
KW - WNK4
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U2 - 10.1152/ajprenal.00232.2019
DO - 10.1152/ajprenal.00232.2019
M3 - Article
C2 - 31736353
AN - SCOPUS:85077760963
VL - 318
SP - F216-F228
JO - American journal of physiology. Renal physiology
JF - American journal of physiology. Renal physiology
SN - 0363-6127
IS - 1
ER -