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).
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.
|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.