C57BL/6-Cxcr3^tm2.1Arsa/J

Stock number: 038023
Product name: Cxcr3^RFP
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

Cxcr3^RFP knock-in mice express red fluorescent protein (RFP) from the endogenous X-linked Cxcr3 gene. They may be useful for tracking Cxcr3-expressing immune cells during infection and disease progression.

Detailed description

In this Cxcr3^RFP strain, an internal ribosome entry site (IRES), a tdTomato red fluorescent protein (RFP), and bovine growth hormone polyadenylation sequence were placed downstream of exon 2 of the X-linked chemokine (C-X-C motif) receptor 3 (Cxcr3) gene. Endogenous Cxcr3 expression is unaffected. Homozygous females and hemizygous males are viable and fertile. Cxcr3 encodes a chemokine receptor involved in immunity, autoimmunity, and progression of diseases such as cancer, and atherosclerosis. The donating investigator notes that the tdTomato fluorescence is measurable by FACS. In these Cxcr3^RFP mice, tdTomato fluorescence is seen on activated Th1 cells, CD8⁺ T cells, NK cells, NKT cells, natural regulatory T cells, as well as innate CD8⁺ T cells.

The donating investigator has also made a Cxcr3^eGFP knock-in mouse line, or CIBER, available (Stock No. 023337).

Development

A targeting vector was designed to insert an internal ribosome entry site (IRES), tdTomato fluorescent protein, and bovine growth hormone polyadenylation sequence, followed by a loxP-flanked neomycin resistance cassette, downstream of exon 2 of the X-linked chemokine (C-X-C motif) receptor 3 (Cxcr3) gene. The construct was electroporated into C57BL/6-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric mice were bred to albino C57BL/6J (Stock No. 000058) mice for one generation. The neomycin cassette was removed by crossing to a Zp3-Cre recombinase line on an B6 congenic background. The resulting Cxcr3^RFP line, with neomycin cassette removed, was then maintained on a C57BL/6JOlaHsd (Envigo) background by the donating laboratory (see SNP note below). Upon arrival at The Jackson Laboratory, it was rederived with C57BL/6J oocytes (Stock No. 000664). Hemizygous sperm was then cryopreserved.

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. Four of the 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating, including the rd8 recessive mutation associated with retinal degeneration on Chromosome 1 within the Crb1 locus. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Cxcr3^tm2.1Arsa
Name: targeted mutation 2.1, Abhay R Satoskar
MGI accession ID: MGI:7518206
Generation method: Targeted
Attributes: Reporter
Synonyms: Cxcr3^RFP
Marker symbol: Cxcr3
Marker name: chemokine (C-X-C motif) receptor 3
Marker synonyms: CD182; Cd183; CKR-L2; CMKAR3; GPR9; IP10-R; MigR; Mig-R
Chromosome: X
Strain of origin: C57BL/6
Molecular note: A targeting vector is designed to insert an internal ribosome entry site (IRES), tdTomato fluorescent protein, and bovine growth hormone polyadenylation sequence, followed by an loxP-flanked neomycin resistance cassette, downstream of exon 2. Cre-mediated recombination removed the neo cassette.
General note: The version of this allele that contains the neomycin selection cassette, Cxcr3^tm2Arsa, has been analyzed.