WNK-SPAK/OSR1 signaling pathway facilitates ictal activity via reduced neuronal chloride extrusion rate
Year: 2026
Type: preprint
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 (E Cl ) and seizures via increased KCC2 activity. However, increased KCC2 activity alone should not affect E Cl whose determinants are more complex. We determined the net effects of WNK-SPAK/OSR1 pathway inhibitor WNK463 on E Cl 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. Our data support a mechanism whereby mutual NKCC1 inhibition and KCC2 activation via the WNK-SPAK/OSR1 pathway exert powerful anti-ictal effects by facilitating [Cl - ] i extrusion during ILDs.
Institutions: Harvard University, Massachusetts General Hospital
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7164513343