Title

Severe deficiency of the voltage-gated sodium channel Na V 1.2 elevates neuronal excitability in adult mice.

Document Type

Article

Publication Date

8-3-2021

Publication Title

Cell Rep

Keywords

JGM

JAX Source

Cell Rep 2021 Aug 3; 36(5):109495

Volume

36

Issue

5

First Page

109495

Last Page

109495

ISSN

2211-1247

PMID

34348148

DOI

https://doi.org/10.1016/j.celrep.2021.109495

Abstract

Scn2a encodes the voltage-gated sodium channel NaV1.2, a main mediator of neuronal action potential firing. The current paradigm suggests that NaV1.2 gain-of-function variants enhance neuronal excitability, resulting in epilepsy, whereas NaV1.2 deficiency impairs neuronal excitability, contributing to autism. However, this paradigm does not explain why ∼20%-30% of individuals with NaV1.2 deficiency still develop seizures. Here, we report the counterintuitive finding that severe NaV1.2 deficiency results in increased neuronal excitability. Using a NaV1.2-deficient mouse model, we show enhanced intrinsic excitability of principal neurons in the prefrontal cortex and striatum, brain regions known to be involved in Scn2a-related seizures. This increased excitability is autonomous and reversible by genetic restoration of Scn2a expression in adult mice. RNA sequencing reveals downregulation of multiple potassium channels, including KV1.1. Correspondingly, KV channel openers alleviate the hyperexcitability of NaV1.2-deficient neurons. This unexpected neuronal hyperexcitability may serve as a cellular basis underlying NaV1.2 deficiency-related seizures.

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