C3.Cg-Scn8a^em1Mm/J

Stock number: 040584
Product name: Scn8a^N1768D
Strain synonyms: Scn8a KI (D/+)
Research areas: Cell Biology Research, Mouse/Human Gene Homologs, Neurobiology Research

Description

Scn8a^N1768D knock-in (KI) mice carry a clinical mutation (N1768D) in the Scn8a gene, on a congenic C3HeB/HeJ genetic background. These mice may be useful for studying epileptic encephalopathy.

Detailed description

Scn8a encodes the 225 kDa alpha subunit of the voltage-gated, type VIII sodium channel (SCN8A), involved in generation and propagation of action potentials in neurons. Gain of function mutations in the Scn8a gene have been associated with epileptic encephalopathy while loss of function mutations may lead to autism spectrum disorders (ASD), developmental delay, and ataxia.

These Scn8a^N1768D knock-in (KI) mice, also referred to as D/+, carry a TALEN-generated point mutation in the final coding exon of the Scn8a gene, resulting in an asparagine to aspartic acid amino acid substitution (N1768D). This mutation was first identified in a patient with epileptic encephalopathy (Veeramah et al, Am J Hum Genet. 2012).

Heterozygous mice are viable but exhibit seizures and shortened lifespan. The donating laboratory has indicated that heterozygous females are poor mothers and do not care for their litters; therefore, it is recommended that the line is maintained through heterozygous males. Note that due to the onset of the phenotype at 3-6 months of age, heterozygous males may only produce 2-3 litters.

Scn8a^N1768D KI mice, on the C3HeB/HeJ (Stock No. 000658) congenic background, have a slight delay in seizure onset and increased median survival (~6 months of age) compared to this allele on a C57BL/6J congenic background (median survival ~4-6 months of age). Long-term rescue of seizures and lethality has been observed with down-regulation of the D allele by anti-sense oligos (ASOs) (Hill et al, 2023). These Scn8a^N1768D KI mice may be useful for studying epileptic encephalopathy.

Note that based on sequencing analysis performed by The Jackson Laboratory, utilizing the Ensembl canonical transcript Scn8a-201 (ENSMUST00000082209.13) as reference, the amino acid substitution location has been updated to N1766D.

Development

This Scn8a^N1768D knock-in (KI) allele, also referred to as D/+, was generated by TALEN-based genome editing to introduce a point mutation (A>G) in exon 26 of the sodium channel, voltage-gated, type VIII, alpha (Scn8a) gene (Jones and Meisler, Genesis 2014). This mutation results in the amino acid substitution of an arginine to aspartic acid (N1768D). Seven more synonymous changes within the TALEN binding sites were also introduced to minimize re-digestion of the targeted allele. TALEN mRNAs were introduced by pronuclear injection into (C57BL/6JXSJL)F2 blastocysts. Offspring were crossed to C3HeB/HeJ for more than 15 generations by the donating laboratory. To establish our live colony, frozen embryos, generated by crossing C3HeB/HeJ (Stock No. 000658) females to heterozygous Scn8a^N1768D males, were recovered.

Note that based on sequencing analysis performed by The Jackson Laboratory, utilizing the Ensembl canonical transcript Scn8a-201 (ENSMUST00000082209.13) as reference, the amino acid substitution location has been updated to N1766D.

Allele

Symbol: Scn8a^em1Mm
Name: endonuclease-mediated mutation 1, Miriam Meisler
MGI accession ID: MGI:5578212
Generation method: Endonuclease-mediated
Attributes: Not Applicable
Synonyms: Scn8a^N1768D; Scn8a^tm1768DMm
Marker symbol: Scn8a
Marker name: sodium channel, voltage-gated, type VIII, alpha
Marker synonyms: ataxia 3; BFIS5; C630029C19Rik; CERIII; CIAT; DEE13; EIEE13; med; mnd2; mnd-2; motor end-plate disease; MYOCL2; NaCh6; Nav1.6; nmf2; nmf335; nmf58; nur14; PN4; seal
Chromosome: 15
Strain of origin: (C57BL/6J x SJL)F2
Molecular note: TALEN technology was used to generate an A to G point mutation in exon 26 that results in the amino acid substitution of aspartic acid for asparagine at position 1766 (N1766D) using Ensembl canonical transcript ENSMUST00000082209.13 Scn8a-201 as reference. Seven more synonymous changes within the TALEN binding sites were introduced to minimize redigestion of the targeted allele. 62 founders were identified with 13 distinct insertion/deletions in 24 mice.