Abstract: TH-OR021
WNK Condensate Formation Drives Kinase Activation and Regulates Electrolyte Homeostasis
Session Information
- Fluids and Electrolytes: Bench and Bedside
November 06, 2025 | Location: Room 361A, Convention Center
Abstract Time: 04:50 PM - 05:00 PM
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1101 Fluid, Electrolyte, and Acid-Base Disorders: Basic
Authors
- Castañeda-Bueno, Maria, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Carbajal-Contreras, Hector, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Magaña, German R., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Su, Xiao-Tong, Oregon Health & Science University, Portland, Oregon, United States
- Tellez Sutterlin, Michelle, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Vázquez, Norma Hilda, Universidad Nacional Autonoma de Mexico, Mexico City, CDMX, Mexico
- Rojas Ortega, Eréndira, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Amnekar, Ramchandra Vijay, MRC Protein Phosphorylation and Ubiquitylation Unit, Dundee, Scotland, United Kingdom
- Alcala Velasco, Edgar Ivan, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Lira-Castañeda, Mario S, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Márquez Salinas, Alejandro, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
- Alessi, Dario, MRC Protein Phosphorylation and Ubiquitylation Unit, Dundee, Scotland, United Kingdom
- Ellison, David H., Oregon Health & Science University, Portland, Oregon, United States
- Gamba, Gerardo, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico
Background
With-No-lysine (K) (WNK) kinases phosphorylate Ste20-related Proline/Alanine-rich Kinase (SPAK) to activate the NaCl cotransporter (NCC) in the distal convoluted tubule (DCT). WNKs form biomolecular condensates, but a role for these condensates remains uncertain. We investigated if WNK condensate formation primarily drives kinase activation and its link to the pathophysiology of Familial Hyperkalemic Hypertension (FHHt), a genetic disease caused by impaired WNK degradation.
Methods
WNK condensation in HEK293 cells was modulated by blue light (Cry2clust fusions) or by tamoxifen (estrogen receptor ligand-binding domain fusion). Chimeras in which the native intrinsically disordered region (IDR) of WNK1 was substituted by the IDR of FUS, TDP-43, DDX3X, or TSC22D2 were generated. Activation induced by condensation was assessed by immunoblot. Cl- measurement of condensate-enriched fractions prepared from cytoplasmic extracts of KS-WNK1-injected X. laevis oocytes was performed. In FHHt mice (KLHL3 R528H), the relation between condensate formation and pathway activation was studied.
Results
Induced WNK condensation by blue light or by tamoxifen activated WNK signaling. The chimeras in which the native IDR of WNK1 was substituted by the IDR of FUS, TDP-43, DDX3X, or TSC22D2 formed condensates in response to blue light, but only full-lengh WNK1 and the WNK1-TSC22D2 chimera increased their autophosphorylation. Reduced [Cl-] was observed in condensate-enriched fractions from cytoplasmic extracts of KS-WNK1-inyected oocytes, but not water-injected oocytes, suggesting WNK condensates functioning as Cl--reduced microdomains.
Despite severe hyperkalemia on a high K+ diet, FHHt mice presented abundant WNK4 condensates in their DCT and no reduction in pNCC. Ex vivo, hypotonic treatment of FHHt tubules reduced WNK4 condensates and reduced pNCC.
Conclusion
WNK condensation drives kinase activation, possibly via Cl--reduced microenvironments and specific IDR properties. In FHHt, aberrant WNK condensates caused by WNK overexpression may explain sustained kinase activity, NCC hyperphosphorylation, and unresponsiveness to high K+, contributing to its pathophysiology.
Funding
- Private Foundation Support