Tbx20f floxed mice possess loxP sites flanking exons 1-3 of the T-box 20 gene. This strain may be useful for studying congenital heart disease and adult cardiomyopathies.
Richard P Harvey, University of New South Wales
These Tbx20f floxed mutant mice possess loxP sites flanking exons 1-3 of the T-box 20 (Tbx20) and a LacZ cassette that becomes expressed after conditional deletion. TBX20 is expressed in the heart and at other sites in the embryo including yolk sac, and is essential for lineage specification and morphogenesis of the developing heart. During development, Tbx20 is expressed in the cardiac crescent prior to heart tube formation, then in myocardium and endocardium of the looping heart. 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 exons 1-3 deleted in cre-expressing tissues and the LacZ cassette will be activated.
For example, when crossed to a strain expressing germline Cre recombinase, resulting offspring exhibit complete embryonic lethality in homozygotes due to yolk sac and heart tube abnormalities, as seen for the Tbx20LacZ null allele (see Stock No. 024664). Heterozygotes are normal, viable, and fertile.
A targeting vector was designed to insert a single loxP site upstream of exon 1 and a loxP-flanked neomycin resistance (neo) cassette followed by a β-galactosidase (lacZ) sequence downstream of exon 3 of the T-box 20 (Tbx20) gene. The construct was electroporated into C57BL/6J-derived Bruce4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric males were bred with C57BL/6J females. Offspring were bred with C57BL/6-Tg(rtetR-tetO-cre)40Mhz/Orl mice to delete the neo cassette. Resulting progeny contained multiple gene rearrangments; intact floxed-exons 1-3, intact floxed-neo cassette, or excision of exons 1-3 and the neo cassette. Resulting offspring, lacking the neo, were bred to C57BL/6J mice for at least 11 generations. 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, Richard P Harvey|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Tbx20, T-box 20|
|Strain of Origin||B6.Cg-Thy1a|
|Molecular Note||A targeting vector was designed to insert a single loxP site 5' of the initiation codon in exon 1 and a loxP-flanked neomycin resistance (neo) cassette followed by a beta-galactosidase (lacZ) sequence downstream of exon 3. Mutant mice were bred to mice carrying Tg(rtetR-tetO-cre)40Mhz. Progeny were selected to retain loxP sites in introns 1 and 3, but an excised neomycin selection cassette.|
When maintaining a live colony, homozygous mice may be bred together.
When using the Tbx20f mouse strain in a publication, please cite the originating article(s) and include JAX stock #024665 in your Materials and Methods section.