129S-Top2b^tm2Jcw/J

Stock number: 008396
Research areas: Neurobiology Research, Research Tools

Description

These Top2β^flox2 (topoisomerase (DNA) II beta) mutant mice may be useful in generating conditional mutations for studying neural development.

Detailed description

These mice possess loxP sites flanking the 3 exons encoding the active-site tyrosyl residue of the targeted gene. Mice that are homozygous for this allele are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have the 3 exons deleted in the cre-expressing tissue(s).

When bred to a strain expressing Cre recombinase during spermatogenesis (see Stock No. 003328 for example), this mutant mouse strain may be useful in studies of neural development.

When bred to a strain expressing Cre recombinase in the telencephalon and discreet head structures (see Stock No. 004337, 006084 for example), this mutant mouse strain may be useful in studies of corticogenesis.

Development

A targeting vector was designed to insert a loxP site and self-excising selection cassette upstream, and a second loxP site downstream of the three exons that encode the active-site tyrosyl residue of the targeted gene. The self-excising selection cassette, containing PGK-neo and FLPe recombinase gene under the control of angiotensin-converting enzyme promoter, is flanked by frt sites. FLPe-mediated recombination during spermatogenesis removed the cassette, leaving one loxP and frt site upstream, and the second loxP site downstream of the three targeted exons. The construct was electroporated into 129S6/SvEvTac-derived TC1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric males were bred to 129SvEv (Taconic) females to generate top2β^flox2 mice. These mice were then backcrossed to 129SvEv (Taconic) for approximately 15 generations prior to arrival at The Jackson Laboratory. Upon arrival, mice were backcrossed to 129S1/SvImJ (Stock No. 002448) for at least one generation to establish the colony.

Allele

Symbol: Top2b^tm2Jcw
Name: targeted mutation 2, James C Wang
MGI accession ID: MGI:3521850
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Top2b
Marker name: topoisomerase (DNA) II beta
Chromosome: 14
Strain of origin: 129S6/SvEvTac
Molecular note: A self excising neomycin resistance cassette together with an upstream loxP site was inserted in one intron (4?) and a second loxP site was inserted in the third downstream exon. The presence or absence of the neomycin cassette was assessed by PCR but did not affect selection of mice for breeding since the resistance cassette was contained between the two loxP sites.