C.129S4(Cg)-Il13^tm2.1Lky/J

Stock number: 018869
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

These Smart13 knock-in mice express a modified human CD4 marker from the mouse Il13 gene locus. They are suitable for use in applications where tracking Il13-expressing hematopoietic cells is desired.

Detailed description

The Smart13 or Il13^Smart allele has a bi-cistronic IRES::CD4*F43I cassette inserted between the translational stop codon and the 3' UTR of the interleukin 13 (Il13) gene. These mice express endogenous Il13 and a cell surface membrane-anchored, non-signaling human CD4 marker. Homozygous Smart13 mice are viable and fertile. Expression of the human CD4 marker is observed in Il13-expressing cells including innate type 2 helper cells (Ih2 cells) and type 2 helper T cells (Th2). These Ih2 cells are lineage-negative innate cells that arise during type 2 immunity or in response to the epithelial cytokines IL-25 and IL-33. Ih2 cells are widely distributed in mouse tissues and are particularly prevalent in mesenteric lymph nodes, spleen, and liver.

Development

A targeting vector was designed to insert a neomycin (neo) resistance cassette, and an internal ribosome entry site (IRES), followed by truncated human CD4 cDNA, between the stop codon and the 3' untranslated region of the interleukin 13 (Il13) gene. The truncated CD4 fragment lacking intracellular signaling capacity, also contained a point mutation resulting in an I to F substitution at position 43 of the protein, rendering the human CD4 marker incapable of interacting with mouse major histocompatibility complex class II (MHCII). The construct was electroporated into 129S4/SvJae-derived PrmCre embryonic stem (ES) cells. These PrmCre (or PC3) ES cells contain the Tg(Prm-cre)70Og transgene with the protamine promoter directing cre expression to the male germline. Correctly targeted ES cells were injected into C57BL/6 blastocysts and the resulting chimeric males were bred to C57BL/6 females to generate a colony of Il13^Smart mice lacking the neo cassette. These mice were backcrossed to BALB/cJ mice (Stock No. 000651) for at least 10 generations. They were then backcrossed with CBy.SJL(B6)-Ptprc^a/J (Stock No. 006584) to generate Smart13 Ly5.1/5.1 homozygotes. Upon arrival at The Jackson Laboratory, mice were bred to BALB/cJ inbred mice for at least one generation to establish a colony.

Allele

Symbol: Il13^tm2.1Lky
Name: targeted mutation 2.1, Richard M Locksley
MGI accession ID: MGI:5435899
Generation method: Targeted
Attributes: Reporter
Marker symbol: Il13
Marker name: interleukin 13
Chromosome: 11
Strain of origin: 129S4/SvJae-Tg(Prm-cre)70Og
Expressed genes: CD4,CD4 molecule,human
Molecular note: A targeting vector was designed to insert a neomycin (neo) resistance cassette, and an internal ribosome entry site (IRES), followed by truncated human CD4 cDNA, between the stop codon and the 3' untranslated region. The truncated CD4 fragment(424 aa vs. 458 aa in full-length protein) lacking intracellular signaling capacity (aa 419-424 as cytoplasmic tail in truncated form vs. aa 419-458 in full-length hCD4), and also contains a point mutation resulting in an I(ATC codon) to F(TTC codon) substitution at position 43 of the protein, rendering the human CD4 marker incapable of interacting with mouse major histocompatibility complex class II (MHCII) and useful as a marker of cells expressing IL13. Cre-mediated recombination removed the neo cassette.