C57BL/6-Gt(ROSA)26Sor^tm1Lkane/J

Stock number: 037253
Product name: FSF-Tim-3, Rosa26^FSF-Tim3

Research areas: Cancer Research, Research Tools

Description

Rosa26^FSF-Tim3 knock-in mice conditionally express mouse Havcr2 (hepatitis A virus cellular receptor 2, also known as Tim-3) and a FLAG tag from the Gt(ROSA)26Sor endogenous promoter upon exposure to Cre recombinase. This strain may be useful for studying Tim-3⁺ Treg cells and cancer.

Detailed description

Havcr2 (hepatitis A virus cellular receptor 2 or Tim-3) encodes a member of the immunoglobulin superfamily and is expressed on CD4+ Th1 cells, CD8+ Tc1 cells, Th17 cells, Treg cells, and innate immune cells. Tim-3 is believed to function as an immune checkpoint inhibitor and is involved in inhibiting T cell responses in autoimmunity and cancer. Specifically, it is involved in the negative regulation of regulatory T (Treg) cells in the tumor microenvironment.

FSF-Tim-3 knock-in mice express conditional Cre recombinase-mediated expression of mouse Havcr2 (hepatitis A virus cellular receptor 2 or Tim-3) and a FLAG epitope tag from the Gt(ROSA)26Sor endogenous promoter. Prior to exposure to Cre recombinase FLAG-tagged Tim-3 is not expressed. In the presence of cre, the STOP cassette is excised allowing constitutive Tim-3 expression in cre-expressing tissues. Mice homozygous for the mutation are viable and fertile.

When FSF-Tim-3 mice are bred to mice with inducible Cre recombinase expression in CD4+ regulatory T cells, (STOCK Foxp3^{tm9(EGFP/cre/ERT2)Ayr}/J, Stock No. 018963), tamoxifen-treated progeny exhibit an increase in Foxp3+ Treg cells in spleen and lymph nodes. These Treg cells display a higher baseline activation than controls.

Development

The targeting construct contains a loxP-flanked STOP cassette (believed to contain a neomycin cassette) and a full length murine FLAG tagged Havcr2 cDNA sequence. This entire construct was inserted into the Gt(ROSA)26Sor locus on chromosome 6. The construct was electroporated into C57BL/6-derived embryonic stem (ES) cells from GenOway. The resulting chimeric animals were maintained on the C57BL/6 background by the donating laboratory (see SNP note below). Upon arrival, sperm was cryopreserved. To establish our live colony, rwcovery was performed with C57BL/6J oocytes (Stock No. 000664).

In 2023, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 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 males sent to The Jackson Laboratory Repository. Two of the 43 markers throughout the genome were segregating for allele-type other than C57BL/6. Also, 1 of the 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. Taken together, these data suggest the mice sent to The Jackson Laboratory Repository (and used to freeze sperm in 2023) were on a predominantly C57BL/6 genetic background (mix of C57BL/6N;C57BL/6J) but also contained other undetermined genetic background contributions.

Allele

Symbol: Gt(ROSA)26Sor^tm1Lkane
Name: targeted mutation 1, Lawrence P Kane
MGI accession ID: MGI:7262883
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Inserted expressed sequence; Epitope tag
Synonyms: FSF-Tim3
Marker symbol: Gt(ROSA)26Sor
Marker name: gene trap ROSA 26, Philippe Soriano
Marker synonyms: beta geo; Gtrgeo26; Gtrosa26; R26; ROSA26; SETD5-AS1; Thumpd3as1
Chromosome: 6
Strain of origin: C57BL/6
Molecular note: The targeting construct contains a loxP-flanked STOP cassette and a full length murine FLAG tagged Hacvr2 cDNA sequence. This entire construct was inserted into the Gt(ROSA)26Sor locus.