SCN1AR613X/WT: A Nonsense Open-access Mouse Model for Dravet Syndrome
Abstract number :
1.129
Submission category :
2. Translational Research / 2D. Models
Year :
2022
Submission ID :
2203980
Source :
www.aesnet.org
Presentation date :
12/3/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:22 AM
Authors :
Vittoria Spinosa, PhD – Dravet Syndrome Foundation Spain; Anat Mavashov, - – Faculty of Medicine, Tel Aviv University; Yael Almog, Mrs – Faculty of Medicine, Tel Aviv University,; Marina Brusel, PhD – Faculty of Medicine, Tel Aviv University,; Moran Rubinstein, PhD – Faculty of Medicine, Tel Aviv University,; José Ángel Aibar, Mr – Dravet Syndrome Foundation Spain
Rationale: Dravet syndrome (Dravet), a severe congenital genetic epilepsy, is caused in ~20% of cases by nonsense variants in the SCN1A gene, which encodes the alpha subunit of the voltage-gated sodium channel NaV1.1. Dravet is characterized by severe and frequent drug-resistant seizures, a high risk of premature mortality, and additional non-epileptic comorbidities, including developmental delay, cognitive and social deficits. Preclinical development of novel targeted therapies requires the use of animal models that recapitulate the disease at the genetic and clinical levels. We present a new open access mouse model of Dravet, carrying the pathogenic R613X nonsense mutation found in patients.
Methods: A CRISPR/Cas9-generated A >T point mutation at nucleotide 1837 (converting Arg613 to a STOP codon) was introduced into exon 12 of the mouse Scn1a gene using 129S1/SvImJ embryos. Mice carrying the R613X mutation (JAX stock 034129), bred on the pure 129S1/SvImJ or a mixed background (129S1/SvImJ: C57BL/6J) were analyzed for their Scn1a mRNA and protein expression, as well as their epileptic and behavioral phenotypes.
Results: The premature stop codon induced by the R613X nonsense mutation reduced Scn1a mRNA and NaV1.1 protein expression levels to ~50% in heterozygous Scn1aR613X/WT, and resulted in marginal background expression in Scn1aR613X/R613X mice. Heterozygous Scn1aR613X/WT mice on the 129S1/SvImJ background were susceptible to thermally induced seizures at postnatal day (P) 16, and later in life (P21 and P35), but did not demonstrate spontaneous convulsive seizures or premature mortality. Nevertheless, Scn1aR613X/R613X on this pure background resulted in complete mortality at P16. Conversely, heterozygous Dravet Scn1aR613X/WT bred on a mixed background demonstrated premature mortality (~50%), spontaneous convulsive seizures, and susceptibility to thermally induced seizures at P16, P21, and P35. In addition to epilepsy, heterozygous Dravet Scn1aR613X/WT of the mixed background also showed hyperactivity in the open field. Furthermore, electrophysiological recordings in acute brain slices of these mice demonstrated reduced firing rates of hippocampal interneurons.
Conclusions: The novel Scn1aR613X/WT mice (JAX stock 034129), on the mixed background (129S1/SvImJ: C57BL/6J), are a valid Dravet animal model that can be used to examine the effectiveness of novel therapies on Dravet-related comorbidities, such as those associated with an SCN1A knock-out allele.
Funding: Dravet Syndrome Foundation Spain
Translational Research