Grin2aS644G is a CRISPR/Cas9 generated mutant of the glutamate receptor, ionotropic, NMDA2A (epsilon 1) gene carrying the S644G missense mutation that is associated with human developmental and early onset epileptic encephalopathy (DEE). These mice may be useful in studying this neurodevelopmental disorder.
Wayne Frankel, Columbia University
The Grin2a gene encodes the GluN2A NMDA receptor (NMDAR) subunit which functions in excitatory synaptic transmission. Rare variants in GRIN2A are associated with a spectrum of disorders, ranging from mild speech and language delay to intractable neurodevelopmental disorders, including but not limited to developmental and early onset epileptic encephalopathy (DEE).
To create the Grin2aS644G allele, CRISPR/Cas9 endonuclease-mediated genome editing of Grin2a was used to introduce the S644G missense variant [p.Ser644Gly; c.1930A4G] that is associated with human DEE.
Both homozygous and heterozygous mutant mice exhibit altered hippocampal morphology at 2 weeks of age. All homozygotes exhibit lethal tonic-clonic seizures by ~17 days (mid-third week). Heterozygous mice display hyperactivity, repetitive and reduced anxiety behaviors and susceptibility to induced generalized seizures. Importantly, heterozygotes also exhibit significant resistance to electrically-induced limbic seizures and to pentylenetetrazole-induced tonic-clonic seizures.
Heterozygous mice are viable and fertile, but females exhibit impaired maternal behaviors (do not care for the pups beyond the first postnatal day, resulting in no surviving pups).
[Amador et al. 2020 Brain 143:2039 (PMID:32577763)]
The Grin2aS644G allele was generated using CRISPR/Cas9 endonuclease-mediated genome editing. Guide RNAs were selected to target the highly conserved third transmembrane region (TM3) of the glutamate receptor, ionotropic, NMDA2A (epsilon 1) gene (Grin2a) on chromosome 16. Oligonucleotide donor DNAs were created encoding a S644G missense mutation (AGT->GGT). These sequences and Cas9 nuclease were introduced into C57BL/6NJ zygotes and transferred to pseudopregnant females. Progeny were screened by PCR and Sanger sequencing to identify correctly targeted pups, which were then bred to C57BL/6NJ mice (Stock No. 005304) for germline transmission. The Grin2aS644G colony was backcrossed to C57BL/6NJ for at least one more generation and then heterozygous sperm was cryopreserved.
Please note, the citation for this Grin2aem2Frk allele is Amador et al. 2020 Brain 143:2039 (PMID:32577763), which refers to it as Grin2aem1(S644G)Frk.
|Allele Name||endonuclease-mediated mutation 2, Wayne N Frankel|
|Allele Type||Endonuclease-mediated (Humanized sequence)|
|Allele Synonym(s)||Grin2aem1(S644G)Frk; Grin2aS644G|
|Gene Symbol and Name||Grin2a, glutamate receptor, ionotropic, NMDA2A (epsilon 1)|
|Strain of Origin||C57BL/6NJ|
|Molecular Note||CRISPR/cas9 genome editing is used to insert a a S644G missense mutation (AGT to GGT) in the highly conserved third transmembrane region (TM3). This mutation has been identified in a patient with developmental and epileptic encephalopathy (DEE).|
Homozygotes exhibit lethal tonic-clonic seizures by ~17 days (mid-third week). Heterozygous mice are viable and fertile, but heterozygous females exhibit impaired maternal behaviors (do not care for the pups beyond the first postnatal day, resulting in no surviving pups).
When maintaining a live colony, wildtype females from the colony or C57BL/6NJ females (Stock No. 005304) may be bred to heterozygous males.
When using the Grin2aS644G mouse strain in a publication, please cite the originating article(s) and include JAX stock #028785 in your Materials and Methods section.