B6.129S2-Emx1^tm1(cre)Krj/J

Stock number: 005628
Product name: Emx1^{IRES cre} , Emx1-Cre
Research areas: Neurobiology Research, Research Tools

Description

Emx1-IRES-Cre knock-in mice have the endogenous Emx1 locus directing expression of Cre recombinase to approximately 88% of the neurons of the neocortex and hippocampus, and in the glial cells of the pallium. These mice are useful in studies of forebrain development and function.

Detailed description

Mice homozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. This strain expresses Cre recombinase from the endogenous Emx1 locus. Western blot analysis of cortical brain tissue does not detect reduced endogenous gene product (protein). When crossed with a strain containing a loxP-site flanked sequence, Cre-mediated recombination results in tissue-specific deletion of the flanked sequence. Recombination occurs in approximately 88% of the neurons of the neocortex and hippocampus, and in the glial cells of the pallium, mimicking the pattern of expression of the endogenous gene. Further, the donating investigator reports that Cre recombinase is also expressed in a subset of male germline cells. Luo et al. 2020 Neuron 106:37 Table 1 shows that Emx1-Cre;floxed double mutant males bred to floxed females produced some offspring with germline deletion of the floxed allele. Our findings with Stock No. 022762 suggest that females may also be similarly affected (2014). Additional links below may or may not have identified germline expression.

View cre expression characterization (for Stock No. 005628).

If the recombinase activity pattern of this allele is further characterized by the Genetic Resource Science group at The Jackson Laboratory, such findings will be reported on the Mouse Genome Informatics (MGI) Allele Detail entry. This same information may also be found searching the MGI Recombinase Activity and MGI Gene Expression + Recombinase Activity Comparison Matrix.

Of note, a similar strain expressing flpo recombinase under control of the same promoter is available as Stock No. 037909.

Development

A targeting vector containing an internal ribosome entry site (IRES) sequence, Cre coding sequence, a polyadenlyation signal and a FRT site flanked PGK-neomycin cassette was inserted 120bp 3' from the stop codon, in the 3' untranslated region. The construct was electroporated into 129S2/SvPas derived D3 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The resulting chimeric animal was crossed to a Flp recombinase expressing strain (FLP-4917) to remove the selection cassette. The mice were then backcrossed to C57BL/6 mice for 12 generations.

Allele

Symbol: Emx1^tm1(cre)Krj
Name: targeted mutation 1, Kevin R Jones
MGI accession ID: MGI:2684610
Generation method: Targeted
Attributes: Recombinase-expressing
Synonyms: Emx1^Cre; Emx1^IREScre; emx1-cre; Emx1-IRES-Cre
Marker symbol: Emx1
Marker name: empty spiracles homeobox 1
Marker synonyms: RGD1564002
Chromosome: 6
Strain of origin: 129S2/SvPas
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: neurons of the neocortex and hippocampus; some germline
Molecular note: An IRES-cre gene followed by an FRT flanked PGK-neomycin gene was inserted 120 bp 3' of the stop codon. The neomycin gene was later removed in vivo by crossing to an Flp recombinase expressing transgenic strain. The protein product of this gene was produced in normal quantities as confirmed by Western blot analysis. Cre recombinase expression was characterized by crossing to a Rosa26 strain.