STOCK Tg(T-cre/ERT2)1Lwd/J

Stock number: 025520
Research areas: Developmental Biology Research, Research Tools

Description

These mice express Cre-ER^T2 under the direction of the T promoter amaking them useful for applications requiring tamoxifen-induced deletion of floxed sequences during axis extension and somitogenesis.

Detailed description

Expression in this Cre-ER^T2 transgenic line is directed by the T (brachyury) promoter/enhancer regions. T encodes a nuclear transcription factor active in progenitor cells that reside within the primitive streak and tail bud, and lineages that emerge from these tissues as the embryonic axis extends. This protein is essential to axis extension and somitogenesis. These mice express Cre-ER^T2 protein in all cells emerging from the primitive streak or tail bud throughout development. Restricted to the cytoplasm, Cre-ER^T2 can only gain access to the nuclear compartment after exposure to tamoxifen. Mice homozygous for the TCreERT2 transgene are viable and fertile. When these mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in the Cre-expressing cells of the offspring.

For example, when bred to mice carrying Gt(ROSA)26Sor^tm1Sor (see Stock No. 003474), 24 hours after tamoxifen induction, widespread βgal activity is seen only in tissues recently emerged from the primitive streak at E7.5 and E8.5 or tailbud at E9.5–13.5. 48 hours after induction, TCreERT2;R26R embryos from E9.5–E12.5 display βgal activity that extends more rostrally.

When bred with B6.129-Ctnnb1^tm2Kem/KnwJ (Stock No. 003474), E8.5 and E10.5 embryos show disruption of somite patterning 48 after tamoxifen administration.

Development

A transgenic vector was generated including 600 bp of the T (brachyury) promoter driving expression of a creER^T2 fusion gene (a Cre recombinase fused to a human estrogen receptor ligand binding domain). This transgene was microinjected into fertilized (C57BL/6NCr X C3H/HeNcr) F2 oocytes. A male from one founder line was bred to a B6C3F1 female, and subsequently to other mutant lines. Contaminating alleles have been bred out of this line, and it has been maintained on a mixed background. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation.

Allele

Symbol: Tg(T-cre/ERT2)1Lwd
Name: transgene insertion 1, Mark Lewandoski
MGI accession ID: MGI:5509185
Generation method: Transgenic
Attributes: Recombinase-expressing; Inducible
Marker symbol: Tg(T-cre/ERT2)1Lwd
Marker name: transgene insertion 1, Mark Lewandoski
Chromosome: UN
Strain of origin: (C57BL/6NCr x C3H/HeNCr)F2
Expressed genes: cre/ERT2,Cre recombinase and estrogen receptor 1 (human) fusion gene,
Site of expression: Cre-ERT2 protein is expressed in all cells emerging from the primitive streak or tail bud throughout development.
Molecular note: The cre recombinase coding region fused to the sequence for a mutated ligand-binding domain of the human estrogen receptor was inserted into a construct where it is under the control of the 500 bp brachyury (T) promoter. Eight transgenic lines were generated and one showed extensive cre activity in presence of tamoxifen but little without tamoxifen induction.
General note: Zygotes for injection were derived by intercrossing B6C3F1 (C57BL/6NCr X C3H/HeNCrMTV) mice.