B6129S-Tg(Foxp3-EGFP/icre)1aJbs/J

Stock number: 023161
Product name: FoxP3-GFP-hCre

Description

These Foxp3-eGFP/cre mice may be useful for fluorescently labeling Foxp3+ T-cells in studies of regulatory T cell function in autoimmunity and to remove loxP-flanked genomic DNA to allow Treg-specific activation/inactivation of conditional genes.

Detailed description

These transgenic mice express an Enhanced Green Fluorescent Protein and codon optimized "humanized" cre recombinase fusion protein under the control of the mouse Foxp3 (forkhead box P3) promoter. Transgene expression is restricted to Foxp3 positive cells from the lymph nodes, spleen and thymus. GFP expression is restricted to FoxP3⁺ cells, which are mainly Cd4⁺Cd25 ^high. The Donating Investigator reports that Cre-mediated recombination and GFP expression is greater in this founder line (1a) than in the related founder line 1c (see Stock No. 008694) The Donating Investigator also reports that on the C57BL/6 background hemizygous pups may be smaller in size than wildtype littermates until to 4-6 weeks of age (after which they resume normal growth) and some hemizygous males may be infertile. On the C57BL/6 background the strain is difficult to breed.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.

Development

The 188 kb C57BL/6J mouse Bacterial Artificial Chromosome (BAC) RP23-143D8, containing the entire Foxp3 (forkhead box P3) gene was modified by inserting an Enhanced Green Fluorescent Protein (EGFP) fused to a codon optimized "humanized" cre recombinase coding sequence. This BAC transgene was injected into NOD/ShiLtJ fertilized oocytes and maintained on the same background. Founder line 1a was subsequently established. The mice were then backcrossed to the C57BL/6 for 7 generations. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony. The mice were then crossed to B6129SF1/J (Stock No. 101043), and maintained by crossing to B6129SF1/J (Stock No. 101043) at every generation.

Allele

Symbol: Tg(Foxp3-EGFP/icre)1aJbs
Name: transgene insertion 1a, Jeffrey Bluestone
MGI accession ID: MGI:4430213
Generation method: Transgenic
Attributes: Recombinase-expressing
Marker symbol: Tg(Foxp3-EGFP/icre)1aJbs
Marker name: transgene insertion 1a, Jeffrey Bluestone
Chromosome: UN
Strain of origin: NOD/ShiLtJ
Expressed genes: GFP,Green Fluorescent Protein,; cre,cre recombinase,bacteriophage P1
Site of expression: Expression is detected in the lymph nodes and spleen.
Molecular note: An EGFP-h-Cre cDNA (GFP fused to a codon-optimized, "humanized" cre recombinase sequence) was inserted directly downstream of the Foxp3 ATG start codon by homologous recombination in a 188-kb C57BL/6 BAC clone (RP23-143D8) containing the entire Foxp3 gene. The purified BAC was injected into pronuclei of nonobese, diabetic mouse embryos. Several founders were generated. GFP expression and lack of functional Foxp3 protein, as indicated by inability of the transgene to rescue Foxp3 null mice were analyzed and line 1 was established. Functional cre activity was assayed by breeding mice to Gt(ROSA)26Sor^tm1(EYFP)Cos reporter mice, and high specificity of recombination was detected in the lymph nodes and spleen. This is the first of two lines derived from founder 1. Cre mediated recombination and GFP expression is greater than in line 1c.