β3flox/floxmice possess loxP sites flanking exon 1 of the integrin beta 3 gene, making this strain useful for studying cell-specific roles of β3-integrins.
Katherine N. Weilbaecher, Washington University School of Medicine
β3flox/flox mice possess loxP sites flanking exon 1 of the integrin beta 3 (Itgb3) gene. Integrin β3 forms heterodimers with Integrin αV or Integrin αIIb to form transmembrane glycoproteins. The resulting αIIbβ3 is expressed on platelets and megakaryocytes and plays a critical role in platelet aggregation. αVβ3 is expressed in multiple cell types and regulates adhesion, migration, proliferation, and survival. Mice that are homozygous for this allele are viable and fertile. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have exon 1 deleted in cre-expressing tissues.
For example, when crossed to C57BL/6-Tg(Pf4-cre)Q3Rsko/J mice (Stock No. 008535) expressing Cre recombinase in the platelets, resulting offspring exhibit a severe bleeding phenotype.
When crossed to B6.129P2-Lyz2tm1(cre)Ifo/J mice (Stock No. 004781) expressing Cre recombinase in myelomonocytic and osteoclast lineages, resulting offspring exhibit osteopetrosis and enhanced tumor growth accompanied by decreased macrophage infiltration.
A targeting vector was designed by Dr Katherine Weilbaecher to insert a single loxP site upstream of exon 1 , and loxP-flanked PGK-neomycin resistance (neo) cassette downstream of exon 1 of the integrin beta 3 (Itgb3) gene. The construct was electroporated into C57BL/6-derived Blu-1 embryonic stem (ES) cells which contain a LacZ reporter fused to β-globin. Correctly targeted ES cells were transiently transfected with a pTURBO-Cre expression plasmid to delete the neo cassette. Resulting ES cells contained multiple gene rearrangments; intact floxed-exon 1, intact floxed-neo cassette, or excision of both exon 1 and the neo cassette. Correctly targeted ES cells, containing only the floxed-exon 1, were injected into C57BL/6J blastocysts and resulting chimeric males were bred with C57BL/6J females by the donating lab (see SNP note below). Resulting offspring were bred to establish a colony of β3flox/flox mice. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
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. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, all 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, Katherine Weilbaecher|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Allele Synonym(s)||B3flox; beta3flox|
|Gene Symbol and Name||Itgb3, integrin beta 3|
|Strain of Origin||C57BL/6NTac-Tg(HBB-lacZ)ALey/Ley|
|General Note||B6/BLU embryonic stem cells contain a LacZ reporter fused to beta-globin and is expressed in peripheral blood cells.|
|Molecular Note||The targeting vector was designed to insert a single loxP site upstream of exon 1 and loxP-flanked PGK-neomycin resistance (neo) cassette downstream of exon 1. The neo cassette was deleted by transiently transfection of a pTURBO-Cre expression plasmid leaving exon 1 floxed.|
When maintaining a live colony mice homozygous for this floxed allele may be bred together.
When using the β3flox mouse strain in a publication, please cite the originating article(s) and include JAX stock #028232 in your Materials and Methods section.