Ifnar1fl is a floxed allele with loxP sites flanking exon 3 of the type-I interferon-α/β receptor gene. Removal of the floxed sequence creates a null allele. These mice may be useful in studying antiviral immune responses, as well as interferon stimulation and JAK-STAT signaling. Mouse mutants involving this gene have been used in studies of Zika virus pathogenesis.
Edward E Schmidt, Montana State University
The Ifnar1fl allele has loxP sites flanking exon 3 of the type-I interferon-α/β receptor gene.
The Ifnar1 gene encodes the type-I-IFN-receptor which, upon binding type-I interferons, activates JAK-STAT signaling pathways critical for regulating growth, survival, differentiation, pathogen resistance and anti-viral immune responses.
Mice homozygous for the floxed allele are viable and fertile with no reported abnormalities.
Cre recombinase-mediated deletion of exon 3 results in a non-functional protein (the exon 2-4 splice variant and frameshift leads to translation of 11 arbitrary (missense) amino acids within the N-terminal extracellular domain followed by a stop codon).
When bred to mice that express Cre recombinase, the resulting offspring may be useful in generating a tissue-specific Ifnar1 knockout. For example, to study myeloid cell-specific Ifnar1-deficiency in specific myeloid populations, breeding Ifnar1fl to Itgax-Cre transgenic mice (Stock No. 008068) or LysMcre knockin/knockout mice (Stock No. 004781) results in Ifnar1 deletion in CD11chigh dendritic cells (Itgax-Cre;Ifnarfl) or macrophages/granulocytes (LysMcre;Ifnarfl), respectively. Further combination with Rag1-deficiency (Stock No. 002216) generates triple mutant mice also lacking mature T cells and B cells (Itgax-Cre;IFragfl or LysMcre;IFragfl, respectively).
A targeting vector was designed by Dr. Edward E. Schmidt (Montana State University) to insert a self-excising frt-Prm1pFlppol2Neo-frt cassette and loxP site in intron 2, and a second loxP site in intron 3 of the type-I interferon-α/β receptor gene (Ifnar1). The construct was electroporated into (C57BL/6 x 129SvEv)F1-derived embryonic stem (ES) cells. Correctly targeted ES cells with the allele targeted onto the C57BL/6 chromosome 16 were selected and injected into recipient blastocysts. Chimeric males were bred with C57BL/6 females; this facilitated self-excision of the frt-Prm1pFlppol2Neo-frt cassette in male germline and resulted in offspring with the Ifnar1fl allele (frt site and loxP site upstream of exon 3, and a second loxP site downstream of exon 3). The Ifnar1fl colony was then bred with C57BL/6-congenic ROSAmT-mG (Stock No. 007676) and C57BL/6-congenic Itgax-Cre (Stock No. 008068). The resulting triple mutant Itgax-Cre;Ifnarfl;ROSAmT-mG/mT-mG was backcrossed to C57BL/6J for three generations. Next, the colony was maintained by sibling matings for eight generations (and the ROSAmT-mG and Itgax-Cre alleles were removed) prior to sending Ifnar1fl males to The Jackson Laboratory Repository in 2015. Upon arrival, additional backcrosses to C57BL/6J inbred mice (Stock No. 000664) were performed to create the C57BL/6J-congenic Ifnar1fl colony as Stock No. 028256.
Of note, the donating investigator reports that, at least once during backcrossing, a heterozygous female was bred to a C57BL/6J inbred male (thus the Y chromosome of the congenic strain is of C57BL/6J origin).
In 2018, 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, on Chromosome 6, was segregating with 129. This SNP has since been bred out of the colony and is currently (as of 2019) C57BL/6-like.
|Allele Name||targeted mutation 1.1, Edward E Schmidt|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Ifnar1, interferon (alpha and beta) receptor 1|
|Strain of Origin||(C57BL/6 x 129S6/SvEvTac)F1|
|Molecular Note||The targeting vector was designed to insert a self-excising FRT-Prm1pFlppol2Neo-FRT cassette and loxP site in intron 2, and a second loxP site in intron 3 of the gene. Facilitated self-excision of the cassette in the male germline and resulted in offspring with one FRT site and loxP site upstream of exon 3, and a second loxP site downstream of exon 3.|
When maintaining a live colony, heterozygous mice may be bred together, to wildtype mice from the colony or to C57BL/6J inbred mice (Stock No. 000664). Alternatively, homozygous mice may be bred together.
When using the Ifnar1fl mouse strain in a publication, please cite the originating article(s) and include JAX stock #028256 in your Materials and Methods section.