Neonatal but not juvenile gene therapy reduces seizures and prolongs lifespan in SCN1B–Dravet syndrome mice
Chunling Chen, … , David R. Hampson, Lori L. Isom
Chunling Chen, … , David R. Hampson, Lori L. Isom
Published January 23, 2025
Citation Information: J Clin Invest. 2025;135(5):e182584. https://doi.org/10.1172/JCI182584.
View: Text | PDF
Research Article Neuroscience Article has an altmetric score of 88

Neonatal but not juvenile gene therapy reduces seizures and prolongs lifespan in SCN1B–Dravet syndrome mice

Abstract

Dravet syndrome (DS) is a developmental and epileptic encephalopathy (DEE) that begins in the first year of life. While most cases of DS are caused by variants in SCN1A, variants in SCN1B, encoding voltage-gated sodium channel β1 subunits, are also linked to DS or to the more severe early infantile DEE. Both disorders fall under the OMIM term DEE52. Scn1b-null mice model DEE52, with spontaneous generalized seizures and death in 100% of animals in the third postnatal week. Scn1b-null cortical parvalbumin-positive interneurons and pyramidal neurons are hypoexcitable. The goal of this study was to develop a proof-of-principle gene replacement strategy for DEE52. We tested an adeno-associated viral vector encoding β1 subunit cDNA (AAV-Navβ1) in Scn1b-null mice. We demonstrated that AAV-Navβ1 drives β1 protein expression in excitatory and inhibitory neurons in mouse brains. Bilateral intracerebroventricular administration of AAV-Navβ1 in Scn1b-null mice at postnatal day 2 (P2), but not at P10, reduced spontaneous seizure severity and duration, prolonged lifespan, prevented hyperthermia-induced seizures, and restored cortical neuron excitability. AAV-Navβ1 administration to WT mice resulted in β1 overexpression in brain but no obvious adverse effects. This work lays the foundation for future development of a gene therapeutic strategy for patients with SCN1B-linked DEE.

Authors

Chunling Chen, Yukun Yuan, Heather A. O’Malley, Robert Duba-Kiss, Yan Chen, Karl Habig, Yosuke Niibori, Samantha L. Hodges, David R. Hampson, Lori L. Isom

×

Figure 1

AAV-Navβ1 administration increases Scn1b and Scn1a mRNA and β1 protein and prolongs lifespan in Scn1b-null mice.

Options: View larger image (or click on image) Download as PowerPoint
AAV-Navβ1 administration increases Scn1b and Scn1a mRNA and β1 protein a...
(A) Absence of Scn1b mRNA in null somatosensory cortex. ****P < 0.0001. (B–I) mRNA abundance in P16–18 mouse somatosensory cortex; RT-qPCR data normalized to WT. Data were analyzed using 2-tailed, unpaired t test except in E, analyzed by 1-way ANOVA. (B) Scn1b in untreated and AAV-Navβ1–treated null. ***P < 0.005. (C) Scn1b in AAV-Navβ1–treated P16–18 WT and null. *P < 0.05. (D) Scn1b in untreated and AAV-Navβ1–treated WT. P = 0.1225. (E) Scn1b in untreated and AAV-Navβ1–treated WT and null. P = 0.1003. (F) Scn1a in untreated WT and null. ****P < 0.0001. (G) Scn1a in untreated and AAV-Navβ1–treated null. **P < 0.0074. (H) Scn1a in AAV-Navβ1–treated WT and null. P = 0.4626. (I) Scn1a in untreated versus AAV-Navβ1–treated WT. P = 0.9431. (J) Western blot analysis of WT (+/+) or null (–/–) mouse brain. Immunoblot (IB): Anti-β1. Bottom: IB of the same blot with anti-tubulin. (K) Western blot analysis of AAV-Navβ1–treated WT (+/+) or null (–/–) brains with or without PNGase F treatment. IB: Anti-β1. Arrow, deglycosylated β1 immunoreactive bands. (L) Single i.c.v. dose of AAV-Navβ1 at P2 improved survival of null (light blue) versus untreated (purple) or AAV-EV–treated null mice (black) through P160 (P < 0.0001, log-rank Mantel-Cox test). Dark blue, untreated WT mice. Kaplan-Meier (Wilcoxon) analysis. (M) Single i.c.v. dose of AAV-Navβ1 at P2 did not increase body weights of null (solid blue line) versus WT mice (dashed black line) through P80 (****P < 0.0001, 2-way ANOVA). (N) Single i.c.v. dose of AAV-Navβ1 at P10 had no effect on null (black) versus untreated null mouse survival (purple; data taken from L) (log-rank Mantel-Cox test). (O) Single i.c.v. dose of AAV-Navβ1 at P2 prevented hyperthermia-induced seizures in P16 null mice. Kaplan-Meier analysis presented for first observed Racine scale 5–6 seizure; uninjected null (purple, n = 5), uninjected WT (dark blue, n = 5), AAV-Navβ1–injected null (light blue, n = 6), or AAV-Navβ1–injected WT mice (black, n = 5). ****P < 0.0001.