STOCK Gad2^{tm1(cre/ERT2)Zjh}/J

Stock number: 010702
Product name: Gad2-CreER
Research areas: Neurobiology Research, Research Tools

Description

Gad2-CreERT2 knock-in/knock-out mice express a tamoxifen-inducible cre recombinase from the endogenous promoter/enhancer elements of the Gad2 gene. When induced, cre activity is observed in the cortex and cerebellum.

Detailed description

The Gad2-CreERT2 knock-in/knock-out allele both abolishes Gad2 gene function and expresses a CreER^T2 fusion protein (creERT2 fusion protein) from the Gad2 promoter/enhancer elements. Heterozygous mice are viable and fertile with no reported abnormalities. Homozygous mice are expected to have a knockout phenotype similar to other null mutations of this gene and may exhibit increased seizure activity (although no early death is reported). Cre-ERT2 fusion gene activity is inducible; observed following tamoxifen administration. As such, when Gad2-CreERT2 mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequences in the Gad2-expressing cells of the offspring.

The donating investigator reports tamoxifen-inducible Cre recombinase activity is specific and efficient (largely recapitulates the endogenous Gad2 expression pattern with highly efficient inducibility). They report tamoxifen-inducible Cre recombinase activity is observed in the cortex and cerebellum, as well as very rare incidence of Cre activity in the cortex prior to tamoxifen administration.

For characterization information, see images at the Allen Institute for Brain Science website (Gad2-CreERT2 images).

The Cre-ERT2 fusion protein consists of Cre recombinase fused to a triple mutant form of the human estrogen receptor which does not bind its natural ligand (17β-estradiol) at physiological concentrations but will bind the synthetic estrogen receptor ligands 4-hydroxytamoxifen (OHT or tamoxifen) and, with lesser sensitivity, ICI 182780. Restricted to the cytoplasm, Cre-ERT2 can only gain access to the nuclear compartment after exposure to tamoxifen. To counteract the mixed estrogen agonist effects of tamoxifen injections, which can result in late fetal abortions in pregnant mice, progesterone may be coadministered.

Development

A targeting vector was designed to insert a CreER^T2 fusion gene (Cre-ER^T2; Cre recombinase fused to a G400V/M543A/L544A triple mutation of the human estrogen receptor ligand binding domain), an SV40 polyA signal, and an frt-flanked neo cassette into the initiation codon of the Gad2 (glutamic acid decarboxylase 2) gene. This construct was electroporated into (C57BL/6 x 129S4Sv/Jae)-derived V6.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric mice were bred with white C57BL/6 mice to originate the colony. Mutant mice were bred with Actin-FLPe mice (on a C57BL/6 congenic background (N10); see Stock No. 005703) to remove the neo selection cassette. These Gad2-CreERT2 mice were subsequently bred with wildtype C57BL/6 mice for at least one generation (and the FLPe transgene was removed) prior to arrival at The Jackson Laboratory. Upon arrival, mice were bred with C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the Gad2-CreERT2 colony.

Allele

Symbol: Gad2^{tm1(cre/ERT2)Zjh}
Name: targeted mutation 1, Z Josh Huang
MGI accession ID: MGI:4355159
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible
Marker symbol: Gad2
Marker name: glutamic acid decarboxylase 2
Chromosome: 2
Strain of origin: (C57BL/6 x 129S4/SvJae)F1
Expressed genes: cre/ERT2,Cre recombinase and estrogen receptor 1 (human) fusion gene,
Site of expression: tamoxifen-inducible Cre recombinase activity is observed in the cortex and cerebellum; very rare incidence of Cre activity is observed in the cortex prior to tamoxifen administration.
Molecular note: A targeting vector was designed to insert a CreERT2 fusion gene (Cre-ERT2; Cre recombinase fused to a G400V/M543A/L544A triple mutation of the human estrogen receptor ligand binding domain), an SV40 polyA signal, and an frt-flanked neo cassette into the initiation codon of the Gad2 (glutamic acid decarboxylase 2) gene. This construct was electroporated into 129 x C57BL/6 hybrid embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric mice were bred with white C57BL/6 mice to originate the colony. Mutant mice were bred with Actin-FLPe mice (on a C57BL/6 congenic background (N10)) to remove the neo selection cassette.
General note: s