The Cnih2fl floxed allele has loxP sites flanking exons 2-5 of the cornichon-2 gene. Removal of the floxed sequence creates a null allele. These mice may be useful in studying the role of synaptic glutamate AMPA receptors in hippocampal synaptic transmission/plasticity, nociception and behavioral, social and cognitive abnormalities, as well as neuropsychiatric disorders such as schizophrenia and depression/mania.
Roger A Nicoll, University of California, San Francisco
Synaptic α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) are the dominant glutamate receptor in the brain. AMPARs are regulated by a family of auxiliary subunits known as transmembrane AMPAR regulatory proteins (TARPs) and the additional AMPAR auxiliary subunits/binding proteins (cornichon). Cornichon-2 (Cnih2) and cornichon-3 (Cnih3) promote receptor trafficking and play a critical role in supporting AMPAR-mediated responses. CNIH2 and CNIH3 bind to the GluA1 subunit of AMPAR in hippocampal neurons, allowing GluA1/A2 receptors to reach the surface. CNIH2/CNIH3 interaction with non-GluA1 subunits may be prevented by TARP γ-8 (Cacng8).
The Cnih2fl floxed allele has loxP sites flanking exons 2-5 of the cornichon-2 gene (Cnih2). When bred to mice that express Cre recombinase, the resulting offspring may be useful in generating a tissue-specific CNIH2 knockout.
For example, following Cre recombinase expression in hippocampal neurons, the resulting CNIH2-deficiency leads to a profound and selective reduction in AMPAR-evoked excitatory postsynaptic currents (AMPAR-eEPSC). When bred to also have the Cnih3fl floxed allele (Stock No. 028443), Cre-mediated knockout of both CNIH2 and CNIH3 in hippocampal neurons results in a similar reduction in amplitude (~20% reduced) but significantly faster decay compared to CNIH2 deletion alone.
Mice homozygous for the Cnih2fl floxed allele are viable and fertile with no reported abnormalities.
The Cnih2fl floxed allele was created by Dr. Roger A. Nicoll (University of California, San Francisco). First, a targeting vector was designed by to have a frt::loxP::PGK-neoR::frt::loxP cassette in intron 1, and a loxP site in intron 5 of the cornichon homolog 2 (Drosophila) gene (Cnih2) on chromosome 19.
The construct was electroporated into iTL BA1 hybrid (C57BL/6 x 129/SvEv) embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric males were bred with C57BL/6J females to establish the colony.
The donating investigator reports that offspring were bred with Flp-transgenic mice (C57BL/6J genetic background) for germline deletion of the neomycin resistance cassette. The resulting Cnih2fl mice were bred together for several generations (and the Flp-expressing transgene was removed). In 2016, Cnih2fl homozygous males with black coat color were sent to The Jackson Laboratory Repository (see SNP note below).
Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
In 2016, a 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the males sent to The Jackson Laboratory Repository. While all 27 markers throughout the genome were C57BL/6 genetic background, the markers that determine C57BL/6 substrains showed a mix of C57BL/6N and C57BL/6J (2 of 5 markers were C57BL/6N, and 2 of 5 markers were C57BL/6N;C57BL/6J). These data show that the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J;C57BL/6N genetic background.
|Allele Name||targeted mutation 1.1, Roger A Nicoll|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Cnih2, cornichon family AMPA receptor auxiliary protein 2|
|Strain of Origin||(C57BL/6NTac x 129S6/SvEvTac)F1|
|Molecular Note||An FRT- and loxP-flanked neomycin resistance cassette was inserted upstream of exon 2. A loxP site was inserted downstream of exon 5. Flp-mediated recombination removed the neomycin resistance cassette and left exons 2 through 5 floxed.|
When maintaining a live colony, heterozygous mice may be bred together or to wildtype mice from the colony. Alternatively, homozygous mice may be bred together.
When using the Cnih2fl mouse strain in a publication, please cite the originating article(s) and include JAX stock #028442 in your Materials and Methods section.