WNK-SPAK/OSR1 signaling pathway facilitates ictal activity via reduced neuronal chloride extrusion rate

Authors

Dzhala, V. I., Shiu, F. H., Rahmati, N., Carroll, A., Bae, R., Kahle, K. T., Staley, K.

Abstract

Seizures upregulate Na+-K+-2Cl- (NKCC1)-mediated Cl- influx and downregulate K+-Cl- (KCC2)-mediated Cl- efflux via the WNK-SPAK/OSR1 kinases, leading to cytoplasmic chloride ([Cl-]i) accumulation, reduced GABAergic inhibition and anticonvulsant failure. Early studies found that inhibiting WNK-kinase reduced baseline [Cl-]i (ECl) and seizures via increased KCC2 activity. However, increased KCC2 activity alone should not affect ECl whose determinants are more complex. We determined the net effects of WNK-SPAK/OSR1 pathway inhibitor WNK463 on ECl and [Cl-]i transients during spontaneous ictal-like discharges (ILDs). We found that WNK463 reduced interictal [Cl-]i but did not change baseline [Cl-]i measured in the presence of TTX. WNK463 enhanced neuronal Cl- extrusion during and after ILDs, before abolishing ILDs. Pharmacological inhibition and targeted siRNA silencing demonstrated that the anti-ictal effects of WNK463 involved both NKCC1 and KCC2. Thus, mutual NKCC1 inhibition and KCC2 activation via the WNK-SPAK/OSR1 pathway exert powerful anti-ictal effects by facilitating [Cl-]i extrusion during ILDs.

Preprint server: bioRxiv
The authors list and abstract were imported from bioRxiv on 13 Jun 2026.

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