BXSB.Cg-Il21^tm1.1Hm/DcrJ

Stock number: 032049
Product name: BXSB.Yaa IL21-VFP
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

This BXSB congenic IL21-VFP knock-in strain expresses VFP (vivid Verde fluorescent protein) from the endogenous Il21 locus and is useful as a reporter for IL21-expressing CD4 T follicular helper (T_FH) cells.

Detailed description

Il21 encodes an immunoregulatory cytokine important in innate and adaptive immune responses. Mutations in this gene have been associated with common variable immunodeficiency-11. This BXSB congenic IL21-VFP knock-in strain expresses VFP (vivid Verde fluorescent protein) from the endogenous Il21 locus and is useful as a reporter for IL21-expressing CD4 T follicular helper (T_FH) cells, which are the precursors of mature T_FH cells. BXSB/MpJ mice (Stock No. 000740) develop a spontaneous autoimmune syndrome similar to lupus, which is accelerated in males (BXSB males have the mutant Yaa-containing Y chromosome). The lupus-like disease is characterized by elevations in T_FH, _ET_FH and IL21. Heterozygotes exhibit a similar increase in percentages of VFP positive cells. The homozygous phenotype has not been characterized. Expression of the endogenous Il21 gene is not altered. This strain uniquely permits investigation into the cellular sources of IL21 in BXSB.Yaa mice.

Green-emitting VFP was isolated from the tropical scleractinian coral, Cyphastrea microphthalma, which rapidly matures at 37°C and exhibits a maximum excitation peak at 491nm and a maximum emission peak at 503 nm, with brighter fluorescence than EGFP.

Development

The targeting vector was designed by Herbert Morse (NIH) to contain an IRES sequence, VFP (vivid Verde fluorescent protein) sequence, and a loxP site flanked PGK-neo cassette. The vector was inserted into the non-coding region of exon 5 of the Il21 gene. The construct was electroporated into unspecified C57BL6/N-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were tested for germline transmission. Mice were crossed to germ-line expressing Cre recombinase transgenic mice, on the C57BL/6 genetic background, to excise the selection cassette. Mice then were crossed to C57BL/6 to breed away from the Cre recombinase transgene. Heterozygotes were intercrossed to generate homozygotes. Mice from the colony were transferred into the laboratory of Derry Roopenian (The Jackson Laboratory) and the Il21 allele was introgressed into the BXSB/MpJ (Stock No. 000740) background for 11 generations.

Allele

Symbol: Il21^tm1.1Hm
Name: targeted mutation 1.1, Herbert Morse III
MGI accession ID: MGI:6095616
Generation method: Targeted
Attributes: Reporter
Synonyms: IL21-VFP
Marker symbol: Il21
Marker name: interleukin 21
Marker synonyms: CVID11; IL-21; Za11
Chromosome: 3
Strain of origin: B6.Cg-Thy1^a
Expressed genes: GFP,Green Fluorescent Protein,
Site of expression: Green fluorescence is detected by flow cytometry in a large number of CD44+ICOS+CD4+ T cells and approximately 40% of PD1+ cells in immunologically challenged Il21^tm1.1Hm mice.
Molecular note: The targeting vector contains an IRES sequence, VFP (vivid Verde fluorescent protein) sequence, and a loxP-flanked PGK-neo cassette inserted into the non-coding region of exon 5. Cre-mediated recombination removed the floxed neo cassette.