CMG2flox/flox mice possess loxP sites flanking exon 12 of the transmembrane domain of the anthrax toxin receptor 2 (Antxr2) gene. They may be useful for studying Bacillus anthracis (anthrax) pathogenesis.
Stephen H. Leppla, National Institute of Allergy and Infectious Diseases
CMG2flox/flox mice possess loxP sites flanking exon 12, encoding the transmembrane domain of the anthrax toxin receptor 2 (Antxr2) gene. CMG2 is one of two Bacillus anthracis (anthrax) toxin receptors. It contains a signal peptide, an extracellular von Willebrand factor A (VWA) domain, a transmembrane domain, and a cytosolic tail. Anthrax toxin protective antigen, the receptor binding moiety of anthrax toxins, has an 11-fold higher affinity for CMG2 than for its other receptor, TEM8 (anthrax toxin receptor 1 (Antxr1). CMG2 is also involved in extracellular matrix adhesion, migration, homing, pattern formation, and signal transduction. Mutations in the transmembrane domain of CMG2 have been associated with the onset of juvenile hyaline fibromatosis (JHF) and infantile systemic hyalinosis (ISH). Mice that are homozygous for this allele are viable and fertile. When bred to mice that express tissue-specific Cre recombinase, resulting offspring will have exon 12 deleted in the cre-expressing tissues.
When bred to ACTB-cre mice, with wide spread expression of Cre recombinase, CMG2-/- mice are highly resistant to both anthrax toxins as well as B. anthracis infection. When subsequently bred to mice lacking TEM8 (anthrax toxin receptor 1 (Antxr1)) (Stock No. 027705), resulting double KO mice are completely resistant to anthrax toxins.
A targeting vector was designed to insert a loxP site upstream of exon 12, and a frt-flanked neomycin resistance (neo) cassette, followed by second loxP site, downstream of exon 12 of the anthrax toxin receptor 2 (Antxr2) gene. The construct was electroporated into Bruce4-derived B6(Cg) embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric males were bred to C57BL/6J females. The donating investigator reported that offspring were bred with B6.Cg-Tg(ACTFLPe)9205Dym/J transgenic mice (Stock No. 005703) to delete the neo cassette, and progeny were crossed to remove the Flp-expressing transgene (see SNP note below). Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.
A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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. Three of the 27 markers throughout the genome were segregating with an unknown source, and 2 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.
|Allele Name||targeted mutation 1.1, Stephen H Leppla|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Antxr2, anthrax toxin receptor 2|
|Strain of Origin||B6.Cg-Thy1a|
|Molecular Note||A loxP site was inserted upstream of exon 12, which encodes the transmembrane domain, and an frt flanked neo cassette and second loxP site were inserted downstream of exon 12. Flp mediated recombination then removed the neo cassette.|
When maintaining a live colony, homozygous mice may be bred together.
When using the CMG2flox mouse strain in a publication, please cite the originating article(s) and include JAX stock #027703 in your Materials and Methods section.