TEM8-/- mice may be useful for studying Bacillus anthracis (anthrax) pathogenesis.
Stephen H. Leppla, National Institute of Allergy and Infectious Diseases
TEM8-/- mice lack exon 13, encoding the transmembrane domain of the anthrax toxin receptor 1 (Antxr1) gene. TEM8 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 lower affinity for TEM8 than for its other receptor, CMG2 (anthrax toxin receptor 2 (Antxr2). TEM8 is also involved in extracellular matrix adhesion, migration, and signal transduction. Mice that are homozygous for this are viable, however the donating investigator reports that homozygous KO females are infertile. TEM8-/- mice show similar sensitivity to a lethal dose of anthrax lethal toxin as control mice, with 90% of these mice succumbing within 2 weeks of infection.
When bred to mice lacking CMG2 (anthrax toxin receptor 2 (Antxr2)) (available with a floxed allele, see Stock No. 027703), resulting double KO mice are completely resistant to anthrax toxin.
A targeting vector was designed to insert a loxP site upstream of exon 13, and a frt-flanked neomycin resistance (neo) cassette, followed by second loxP site, downstream of exon 13 of the anthrax toxin receptor 1 (Antxr1) gene. The construct was electroporated into 129S1/Sv-Oca2+ Tyr+ Kitl+-derived W9.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric males were bred to C57BL/6J females. Offspring were bred with Cre Recombinase expressing mice on a C57BL/6J background to delete the neo cassette and exon 13, and progeny were crossed to remove the cre-expressing transgene. These mice were maintained on a mixed background. Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.
|Allele Name||targeted mutation 1.2, Stephen H Leppla|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Antxr1, anthrax toxin receptor 1|
|Strain of Origin||129S1/Sv-Oca2+ Tyr+ Kitl+|
|Molecular Note||A loxP site was inserted upstream of exon 13, which encodes the transmembrane domain, and an frt flanked neo cassette and second loxP site were inserted downstream of exon 13. Cre mediated recombination then removed exon 13 l and (when present) the neo cassette leaving behind a single loxP site. Western blot analysis confirmed the absence of protein expression in lysates from homozygous MEFs but a mutant protein was detected in conditioned media from homozygous MEFs.|
When maintaining a live colony, heterozygous females may be bred to homozygous males. The donating investigator reports that homozygous KO females are infertile. These mice progressively develop misaligned incisor teeth from weaning age to 3 months of age and require feeding of soft food.
When using the TEM8- mouse strain in a publication, please cite the originating article(s) and include JAX stock #027705 in your Materials and Methods section.