STOCK Foxp3^{tm9(EGFP/cre/ERT2)Ayr}/J

Stock number: 016961
Product name: Foxp3^{eGFP-Cre-ERT2}
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

Foxp3^{EGFP-cre-ERT2} mutant mice contain an internal ribosome entry site (IRES) and an enhanced green fluorescent protein (EGFP) fused to a CreER^T2 fusion gene downstream of the internal stop codon of the forkhead box P3 (Foxp3) gene. These mice may be useful for studying lineage stability and genetic mapping of regulatory T cells.

Detailed description

Foxp3^{EGFP-cre-ERT2} mutant mice contain an internal ribosome entry site (IRES) and an enhanced green fluorescent protein (EGFP) fused to a CreER^T2 fusion gene (Cre recombinase fused to a G400V/M543A/L544A triple mutation of the human estrogen receptor ligand binding domain) downstream of the internal stop codon of the forkhead box P3 (Foxp3) gene. Homozygous females and hemizygous males are viable, fertile, and normal in size. FOXP3 is a transcription factor required for the development and function of regulatory T (T _reg) cells, which are required for suppression of self-reactive T cells and prevention of some autoimmune diseases. In these mice, EGFP expression is evident in FOXP3⁺ T_reg cells. Cre-ER^T2 fusion gene activity is inducible; observed in the same cells only following tamoxifen administration. When Foxp3^{EGFP-cre-ERT2} mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in T _reg cells of the offspring. For example, when these mice are bred with mice containing the Gt(ROSA)26Sortm1(EYFP)Cos allele, deletion of the floxed-STOP cassette in T _reg cells results in 3 populations of CD4⁺ cells: unlabeled FOXP3^- cells, EGFP⁺ YFP^- FOXP3⁺ cells, and EGFP⁺ YFP⁺ FOXP3⁺ cells. These mice may be useful for studying lineage stability and genetic mapping of regulatory T cells.

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

The Foxp3^{EGFP-cre-ERT2} targeting vector was designed with an internal ribosome entry site (IRES), and an enhanced green fluorescent protein (EGFP) fused to a CreER^T2 fusion gene (Cre recombinase fused to a G400V/M543A/L544A triple mutation of the human estrogen receptor ligand binding domain), followed by a frt-flanked neomycin (neo) resistance cassette. This construct was inserted downstream of the internal stop codon of the X-linked forkhead box P3 (Foxp3) gene. This construct was injected into (129X1/SvJ x 129S1/Sv)F1-Kitl⁺-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts, and the resulting chimeric males were bred to FLP-deleter mice (on a B6 background) to remove the neo cassette. These mice were then backcrossed to C57BL/6J mice for at least 3 generations. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation.

Allele

Symbol: Foxp3^{tm9(EGFP/cre/ERT2)Ayr}
Name: targeted mutation 9, Alexander Y Rudensky
MGI accession ID: MGI:4950935
Generation method: Targeted
Attributes: Recombinase-expressing; Reporter; Inducible
Marker symbol: Foxp3
Marker name: forkhead box P3
Chromosome: X
Strain of origin: Not Specified
Expressed genes: GFP,Green Fluorescent Protein,; cre/ERT2,Cre recombinase and estrogen receptor 1 (human) fusion gene,
Site of expression: Expression is seen in regulatory T cells.
Molecular note: An IRES element followed by an EGFP-cre-ERT2 coding sequence was knocked into the 3' UTR of the Foxp3 locus.