STOCK Scn1a^em1Odwd/J

Stock number: 036177
Product name: Scn1a^KT, Scn1a*K1270T, K1259T

Research areas: Developmental Biology Research, Neurobiology Research, Reproductive Biology Research

Description

Scn1a^KT mice carry a CRISPR/Cas9-generated K1259T missense mutation (homologous to human K1270T; also called KT) in this model of GEFS+ (Genetic Epilepsy with Febrile Seizure plus). This mutation causes heat-induced seizure activity.

Detailed description

A K1270T (KT) mutation in the SCN1A (sodium channel, voltage-gated, type I, alpha) gene is linked to GEFS+ (Genetic Epilepsy with Febrile Seizure plus) in humans. This mutation causes heat-induced seizure activity associated with a temperature-dependent decrease in GABAergic neuron excitability in a Drosophila knock-in model.

These Scn1a^KT mice carry a homologous CRISPR/Cas9-generated K1259T GEFS+ missense mutation in the mouse Scn1a gene. This mutation is located in the S2 transmembrane segment of domain III of the alpha subunit of the Nav1.1 ion channel.

Homozygous mice on a C57BL/6NJ background display spontaneous seizures starting around postnatal days 14-16 (P14‐P16) and die by P25. Heterozygous mice are viable and appear to have a normal lifespan (at least 6 months). Heterozygous male mice are unable to impregnate dams if they are older than 14 weeks of age; heterozygous females have normal fertility. Roughly 20% of heterozygous mice may also show spontaneous seizures. All heterozygous mice tested between 30 and 40 days of age display hyperthermia (heat)‐induced seizures at a body temperature 42.7 + 0.06 ^oC. Results suggest that a constitutive decrease in inhibitory interneuron excitability contributes to the seizure phenotype in the mouse model.

The strain is currently on a mixed genetic background that has not been fully characterized or compared with the originally-published C57BL/6NJ genetic background (Das, 2021 - in press).

Development

A K1259T (nucleotide AAA to ACC) missense mutation that is homologous to the human K1270T mutation was introduced to exon 19 of the mouse Scn1a gene using CRISPR/Cas9 methodologies. A silent EcoRV site mutation used for genotyping was introduced downstream of K1270T, and 2 additional silent insertional mutations flank the K1270T mutation to prevent Cas9 activity on the repaired allele. The allele was created in B6SJLF2/J mouse embryos. Resultant mice were backcrossed to C57BL/6J (Stock No. 005304) for 12 generations. Mice were subsequently crossed with both PV-Cre (B6.129P2-Pvalb^tm1(cre)Arbr/J, Stock No. 017320) and Ai14-td-Tomato reporter (B6;129S6-Gt(ROSA)26Sor^{tm14(CAG-tdTomato)Hze}/J, Stock No. 007908) mice for experiments. These secondary alleles were later bred out of the colony, but made additional C57BL/6 and 129 genetic background contributions. The donating lab found no evidence of off-target mutations at 3 potential sites.

 

Allele

Symbol: Scn1a^em1Odwd
Name: endonuclease-mediated mutation 1, Diane O'Dowd
MGI accession ID: MGI:6507747
Generation method: Endonuclease-mediated
Attributes: Humanized sequence
Synonyms: Scn1a*K1259T; Scn1a^KT
Marker symbol: Scn1a
Marker name: sodium channel, voltage-gated, type I, alpha
Marker synonyms: DEE6; DEE6A; DEE6B; DRVT; EIEE6; FEB3; FEB3A; FHM3; GEFSP2; HBSCI; NAC1; Nav1.1; SCN1; SMEI
Chromosome: 2
Strain of origin: (C57BL/6 x SJL)F2
Molecular note: A K1259T (nucleotide AAA to ACC) missense mutation that is homologous to the human K1270T mutation was introduced to exon 19 using CRISPR/Cas9 methodologies. A silent EcoRV site mutation used for genotyping was introduced downstream of K1270T, and 2 additional silent insertional mutations flank the K1270T mutation to prevent Cas9 activity on the repaired allele.