C57BL/6N-Ifng^em1Kamm/Mmjax

Stock number: 038304
Product name: IFNγ^ΔKRKR
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

IFNγ^ΔKRKR mice have a 12 base pair deletion that removes the four positively charged C-terminal amino acids (KRKR) in the extracellular matrix (ECM)-binding domain of the Ifng (interferon gamma) gene. The deletion disrupts binding of heparin sulfate but does not affect IFNGR binding. Homozygous mice have no obvious phenotype but are more susceptible to chronic viral infection (LCMV) than controls.

Detailed description

Ifng (interferon gamma) encodes a cytokine secreted by cells of the immune system. Ifng is involved in the cellular response to viral and microbial infections. IFNγ^ΔKRKR mice are a CRISPR/Cas9 generated hypomorph that carry a 12 base pair deletion removing the four positively charged C-terminal amino acids (KRKR) in the extracellular matrix (ECM)-binding domain. Loss of KRKR disrupts binding of heparin sulfate but allows binding to the interferon gamma receptor (IFNGR). Mice homozygous for the allele are viable and fertile with no obvious phenotype under SPF conditions. Homozygous IFNγ^ΔKRKR mice infected with lymphocytic choriomeningitis virus (LCMV)-Docile develop increased levels of serum IFNG, weight loss, reduced peripheral body temperature, decreased numbers of red blood cells and platelets, decreased hemoglobin, some liver necrosis, and reduced liver and spleen weights. Seven of twelve infected IFNγ^ΔKRKR mice succumbed to immunopathology. LCMV-Docile induces a self-limiting infection with prolonged immune stimulation.

Development

CRISPR/Cas9 endonuclease-mediated genome editing was used to create a 12 base pair deletion in exon 4 of the Ifng locus on chromosome 10. The mutation removes the KRKR coding sequence. Two guide RNAs (5'-ccagcctcaggaagcg gaaa-3'; 5'-cggaatccagcctcaggaag-3'), cas9 endonuclease and a 120-nucleotide (nt) repair template were electroporated into C57BL/6N-derived zygotes. Embryos were transferred to pseudopregnant females. Correctly targeted pups were bred to C57BL/6N mice for germline transmission and then bred to C57BL/6N for an additional 2 generations. The colony was maintained on the C57LB/6N background prior to sending males to The Jackson Laboratory in 2024. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).

In 2024, 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. All 43 markers throughout the genome suggested a C57BL/6N genetic background. Furthermore, the C57BL/6 substrain markers suggest the mice sent to The Jackson Laboratory Repository (and used for the frozen sperm in 2024) were on a C57BL/6NCrl genetic background.

Allele

Symbol: Ifng^em1Kamm
Name: endonuclease-mediated mutation 1, Thomas Kammertoens
MGI accession ID: MGI:7565456
Generation method: Endonuclease-mediated
Attributes: Not Applicable
Synonyms: Ifngamma^deltaKRKR
Marker symbol: Ifng
Marker name: interferon gamma
Marker synonyms: If2f; Ifg; IFI; IFNG2; IFN-gamma; IMD69
Chromosome: 10
Strain of origin: C57BL/6N
Molecular note: CRISPR/Cas9 endonuclease-mediated genome editing is used to create a 12 base pair deletion in exon 4. The mutation removes the KRKR coding sequence. Two guide RNAs (5'-ccagcctcaggaagcg gaaa-3'; 5'-cggaatccagcctcaggaag-3'), cas9 endonuclease and a 120-nucleotide (nt) repair template are used. The deletion disrupts binding of heparin sulfate but does not affect IFNGR binding.