B6.Cg-Cd19^tm1(cre)Cgn Ikzf3^tm1.1Cjwu/J

Stock number: 035514
Product name: Cd19-Cre/Ikzf3fl
Strain synonyms: Ikzf3^Homo
Research areas: Cancer Research, Hematological Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

These Ikzf3-L161R Cd19cre mice contain a cre-conditional L161R mutation in the Ikzf3 gene, and also contain B cell-expressing cre recombinase allele. These mutant mice are useful when studying chronic lymphocytic leukemia (CLL).

Detailed description

The targeted Ikzf3 gene encodes IKAROS family zinc finger 3, a hematopoietic-specific transcription factors involved in the regulation of lymphocyte development. This mutation is analogous to the human IKZF3-L162R mutation associated with malignant transformation of B cells in chronic lymphocytic leukemia (CLL). CLL is the most common B cell leukemia in adults, involving the peripheral blood and lymphoid organs such as lymph nodes and bone marrow. Ikzf3-L161R conditional knock-in mice carry an allele with a knock-in sequence of loxP sites flanking copies of exons 5-8 and a STOP codon. cDNA encoding exons 5, containing a leucine to arginine mutation (L161R), followed by exon 6-8, were inserted downstream of the second loxP site. Cre recombinase activity results in deletion of the floxed exons 5-8 and the STOP codon, allowing expression of the mutant allele. Homozygous Ikzf3-L161R knock-in mice are viable and fertile.

This strain also contains a Cd19cre allele present in Stock No. 006785 mice, resulting in removal of exons 5-8 and the STOP codon and subsequent expression of Ikzf3-L161R specifically in B cells. Expression of the L161R mutation disrupts B cell development and induced CLL-like disease in elderly mice (15-18 months of age with ~40% penetrance) due to hyperactivation of B Cell Receptor/NF-κB target genes.

Of note, a single allelic strain only containing the conditional Ikzf3-L161R allele is available as Stock No. 033284.

Development

The Ikzf3-L161R targeting vector contains a loxP site inserted downstream of exon 4 and a second loxP, site followed by a STOP codon, downstream of exon 8 of the IKAROS family zinc finger 3 (Ikzf3) gene. A frt-flanked neomycin resistance cassette and cDNA encoding exons 5, containing a leucine to arginine mutation (L161R), followed by exons 6-8, were inserted downstream of the second loxP site. The L161R mutation is analogous to the human IKZF3-L162R mutation associated with malignant transformation of B cells in chronic lymphocytic leukemia (CLL). The construct was electroporated into embryonic stem (ES) cells derived from an unknown strain. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric animals were bred to germline FLP deleter mice to remove the neo cassette. Resulting mice, lacking the neo cassette, were then bred to Cd19cre mice (Stock No. 006785) before being backcrossed to C57BL/6J for 10 generations by the donating laboratory (see SNP note below). Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664). The FLP used to remove the neo cassette was found to be still present in mice that arrived, and it is evident that this FLP removed the frt-flanked neo cassette that was part of the Cd19cre allele. The FLP-expressing allele was subsequently bred out of this colony by crossing mice to C57BL/6J mice.

In 2021, 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 rederived living colony at The Jackson Laboratory Repository. One of the 43 markers throughout the genome was segregating with an unknown source. Also, one of the 5 markers that determine C57BL/6J from C57BL/6N was found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Cd19^tm1(cre)Cgn
Name: targeted mutation 1, University of Cologne
MGI accession ID: MGI:1931143
Generation method: Targeted
Attributes: Recombinase-expressing
Synonyms: B-Cre; CD19-; Cd19^Cre; Cd19cre; CD19-Cre; CD19-KO
Marker symbol: Cd19
Marker name: CD19 antigen
Marker synonyms: B4; CVID3
Chromosome: 7
Strain of origin: 129P2/OlaHsd
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: B cells
Molecular note: In-frame insertion of a cre recombinase gene into the first coding exon followed by an fFRT site flanked neomycin resistance gene cassette. A frameshift mutation was also introduced into exon 5. This allele expresses cre recombinase specifically in B lineage cells throughout development.

Allele

Symbol: Ikzf3^tm1.1Cjwu
Name: targeted mutation 1.1, Catherine Wu
MGI accession ID: MGI:6437069
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Humanized sequence
Synonyms: Ikzf3-L161R
Marker symbol: Ikzf3
Marker name: IKAROS family zinc finger 3
Marker synonyms: 5830411O07Rik; AIO; Aiolos; IMD84; Zfpn1a3; ZNFN1A3
Chromosome: 11
Strain of origin: Not Specified
Molecular note: The targeting vector contains a loxP site inserted downstream of exon 4 and a second loxP, site followed by a STOP codon, downstream of exon 8 of the gene. An FRT-flanked neomycin resistance cassette and cDNA encoding exons 5, containing a leucine to arginine mutation (L161R), followed by exons 6-8, were inserted downstream of the second loxP site. Flp-mediated recombination removed the FRT-flanked neo cassette. The L161R mutation is analogous to the human IKZF3-L162R mutation associated with malignant transformation of B cells in chronic lymphocytic leukemia (CLL).