Plural Molecular and Cellular Mechanisms of Pore Domain

Authors

Timothy J Abreo
Emma C Thompson
Anuraag Madabushi
Kristen L Park
Heun Soh
Nissi Varghese
Carlos G Vanoye
Kristen Springer
Jim Johnson
Scotty Sims
Zhigang Ji
Ana G Chavez
Miranda J Jankovic
Bereket Habte
Aamir R Zuberi
Cathleen M Lutz
Zhao Wang
Vaishnav Krishnan
Lisa Dudler
Stephanie Einsele-Scholz
Jeffrey L Noebels
Alfred L George
Atul Maheshwari
Anastasios Tzingounis
Edward C Cooper

Publication Date

1-6-2025

Journal

eLife

DOI

10.7554/eLife.91204

PMID

39761077

PMCID

PMC11703504

PubMedCentral® Posted Date

1-6-2025

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

KCNQ2 Potassium Channel, Animals, Humans, Mice, Pyramidal Cells, Male, Female, Brain Diseases, Cryoelectron Microscopy, Phenylenediamines, Epilepsy, Disease Models, Animal, Carbamates, Nerve Tissue Proteins

Abstract

KCNQ2 variants in children with neurodevelopmental impairment are difficult to assess due to their heterogeneity and unclear pathogenic mechanisms. We describe a child with neonatal-onset epilepsy, developmental impairment of intermediate severity, and KCNQ2 G256W heterozygosity. Analyzing prior KCNQ2 channel cryoelectron microscopy models revealed G256 as a node of an arch-shaped non-covalent bond network linking S5, the pore turret, and the ion path. Co-expression with G256W dominantly suppressed conduction by wild-type subunits in heterologous cells. Ezogabine partly reversed this suppression. Kcnq2G256W/+ mice have epilepsy leading to premature deaths. Hippocampal CA1 pyramidal cells from G256W/+ brain slices showed hyperexcitability. G256W/+ pyramidal cell KCNQ2 and KCNQ3 immunolabeling was significantly shifted from axon initial segments to neuronal somata. Despite normal mRNA levels, G256W/+ mouse KCNQ2 protein levels were reduced by about 50%. Our findings indicate that G256W pathogenicity results from multiplicative effects, including reductions in intrinsic conduction, subcellular targeting, and protein stability. These studies provide evidence for an unexpected and novel role for the KCNQ2 pore turret and introduce a valid animal model of KCNQ2 encephalopathy. Our results, spanning structure to behavior, may be broadly applicable because the majority of KCNQ2 encephalopathy patients share variants near the selectivity filter.