Kidney-specific WNK1 amplifies kidney tubule responsiveness to potassium via WNK body condensates
Cary R. Boyd-Shiwarski, … , Ossama B. Kashlan, Arohan R. Subramanya
Cary R. Boyd-Shiwarski, … , Ossama B. Kashlan, Arohan R. Subramanya
Published June 10, 2025
Citation Information: J Clin Invest. 2025;135(15):e188792. https://doi.org/10.1172/JCI188792.
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Research Article Cell biology Nephrology

Kidney-specific WNK1 amplifies kidney tubule responsiveness to potassium via WNK body condensates

Abstract

To maintain potassium homeostasis, the kidney’s distal convoluted tubule (DCT) evolved to convert small changes in blood [K+] into robust effects on salt reabsorption. This process requires NaCl cotransporter (NCC) activation by the with-no-lysine (WNK) kinases. During hypokalemia, the kidney-specific WNK1 isoform (KS-WNK1) scaffolds the DCT-expressed WNK signaling pathway within biomolecular condensates of unknown function termed WNK bodies. Here, we show that KS-WNK1 amplified kidney tubule reactivity to blood [K+], in part via WNK bodies. In genetically modified mice, targeted condensate disruption trapped the WNK pathway, causing renal salt wasting that was more pronounced in females. In humans, WNK bodies accumulated as plasma potassium fell below 4.0 mmol/L, suggesting that the human DCT experiences the stress of potassium deficiency, even when [K+] is in the low-to-normal range. These data identify WNK bodies as kinase signal amplifiers that mediate tubular [K+] responsiveness, nephron sexual dimorphism, and BP salt sensitivity. Our results illustrate how biomolecular condensate specialization can optimize a mammalian physiologic stress response that impacts human health.

Authors

Cary R. Boyd-Shiwarski, Rebecca T. Beacham, Jared A. Lashway, Katherine E. Querry, Shawn E. Griffiths, Daniel J. Shiwarski, Sophia A. Knoell, Nga H. Nguyen, Lubika J. Nkashama, Melissa N. Valladares, Anagha Bandaru, Allison L. Marciszyn, Jonathan Franks, Mara Sullivan, Simon C. Watkins, Aylin R. Rodan, Chou-Long Huang, Sean D. Stocker, Ossama B. Kashlan, Arohan R. Subramanya

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Figure 5

Dysregulated WNK4-SPAK/OSR1 pathway activity in KS-WNK1–KO mice during K+ restriction, but not during K+ loading.

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Dysregulated WNK4-SPAK/OSR1 pathway activity in KS-WNK1–KO mice during K...
Immunoblot analysis of kidney cortical extracts from female and male WT littermates and KS-WNK1–KO mice subjected to various K+ maneuvers for 10 days. (A–C) Immunoblot of the WNK-SPAK/OSR1 pathway from mice treated with control diet or (A) low K+ diet, (B) HKB diet, or (C) HKB + amiloride. Brackets indicate the band analyzed. In A–C, lanes corresponding to WT and KO animals on control diet were from replicate lysates to facilitate normalization between blots. The values graphed for control diet in Figures D and E represent an average of the replicates (Supplemental Figure 6). (D) WT mice fed a low K+ diet had significant increases in tSPAK, pSPAK/pOSR1, and WNK4 compared with WT mice on control diet. KS-WNK1–KO mice had a blunted response to the low K+ diet compared with WT mice. (E) Phosphorylated-to-total SPAK ratio in WT and KO mice subjected to control vs. low K+ diet. (F) No differences in WNK4-SPAK/OSR1 pathway abundance or phosphorylation in WT and KS-WNK1–KO mice subjected to HKB or HKB + amiloride treatment. (G) WNK-SPAK/OSR1 pathway activation during low, control, and high blood [K+] experimental maneuvers. During low [K+], KS-WNK1–dependent WNK bodies condense the WNK-SPAK/OSR1 pathway; this correlates with SPAK/OSR1 and NCC phosphoactivation. During high K+, KS-WNK1 inhibits pNCC activation independently of the SPAK/OSR1 pathway. Results are shown as mean ± SEM; n = 12 mice per genotype and diet (males and females combined). Two-way ANOVA with Šídák’s multiple comparisons test, *P ≤ 0.05, **P ≤ 0.01.