B6.Cg-Ikzf3^tm1.1Cjwu/J

Stock number: 033284
Product name: Ikzf3 L161R flox
Research areas: Cancer Research, Research Tools

Description

These Ikzf3-L161R mice contain a conditional L161R mutation in the Ikzf3 gene making 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 mutations 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 exon 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.

When bred to Cd19cre mice (Stock No. 006785), resulting offspring lack endogenous exons 5-8 and the STOP codon, and express 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 strain containing the conditional Ikzf3-L161R allele and the Cd19cre allele is available as Stock No. 035514.

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 exon 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 removed 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). Some mice were further crossed to C57BL/6J to remove the Cd19cre allele, resulting in this single Ikzf3-L161R strain.

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 males sent to The Jackson Laboratory Repository. 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.