B6(Cg)-Dlx5^{tm1(cre/ERT2)Zjh}/J

Stock number: 010705
Product name: Dlx5-CreERT2 KIKO
Research areas: Neurobiology Research, Research Tools

Description

The Dlx5-CreERT2 knock-in/knock-out allele both abolishes Dlx5 (distal-less homeobox 5) gene function and expresses a CreERT2 fusion protein from the Dlx5 promoter/enhancer elements.

Detailed description

The Dlx5-CreERT2 knock-in allele both abolishes Dlx5 gene function and expresses a CreER^T2 fusion protein (creERT2 fusion protein) from the Dlx5 promoter/enhancer elements. Heterozygous mice are viable and fertile. Homozygous mice are expected to have a knockout phenotype similar to other null mutations of this gene and may exhibit prenatal/perinatal death with craniofacial and nervous system abnormalities. Cre-ERT2 fusion gene activity is inducible; observed following tamoxifen administration. As such, when Dlx5-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 Dlx5-expressing cells of the offspring.

The donating investigator reports tamoxifen-inducible Cre recombinase activity is specific and efficient (largely recapitulates the endogenous Dlx5 expression pattern with highly efficient inducibility). They report tamoxifen-inducible Cre recombinase activity is observed in the cortex, as well as very rare incidence of Cre recombinase activity in the cortex prior to tamoxifen administration.

For characterization information, see images at the Allen Institute for Brain Science website (Dlx5-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 Dlx5 (distal-less homeobox 5) gene. This construct was electroporated into C57BL/6-derived Bruce4 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. The donating investigator reported that these Dlx5-CreERT2 mice were subsequently bred with wildtype C57BL/6 mice (see SNP note below) 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 Dlx5-CreERT2 colony.

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 rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, at least 1 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Dlx5^{tm1(cre/ERT2)Zjh}
Name: targeted mutation 1, Z Josh Huang
MGI accession ID: MGI:4355155
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible; Null/Knockout
Synonyms: Dlx5-CreER; Dlx5-CreERT2
Marker symbol: Dlx5
Marker name: distal-less homeobox 5
Marker synonyms: RDLX; SHFM1; SHFM1D
Chromosome: 6
Strain of origin: C57BL/6
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.
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 Dlx5 (distal-less homeobox 5) gene. This construct was electroporated into C57BL/6 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.