B6.129S6(Cg)-Gli1^{tm3(cre/ERT2)Alj}/RtigJ

Stock number: 038495
Product name: Gli1-CreER
Strain synonyms: C57BL/6.Gli1-CreER^T2
Research areas: Neurobiology Research, Research Tools

Description

Gli1-CreER knock-in/knock-out mice express a CreER fusion protein driven by the GLI-Kruppel family member GLI1 (Gli1) endogenous promoter, while abolishing endogenous Gli1 expression. When these mice are bred with mice containing a loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in the Gli1-expressing cells of the offspring. These mice may be useful for studying axis patterning, proliferation, and cell fate specification of Hedgehog responding cells at different stages of embryogenesis.

Of note, the same Gli1-CreER allele is also available on a mixed genetic background as Stock No. 007913.

Detailed description

Gli1 encodes a transcription factor that is activated by the sonic hedgehog signal transduction cascade and regulates stem cell proliferation. These Gli1-CreER knock-in/knock-out (KI/KO) mice express a CreER fusion protein driven by the the GLI-Kruppel family member GLI1 (Gli1) endogenous promoter, while abolishing endogenous Gli1 expression, on C57BL/6J-congenic background.

Homozygous mice are viable. The donating laboratory has indicated that homozygous Gli1-CreER KI/KO mice are expected to demonstrate the same infertility issues as the original Gli-CreER^T2 mouse line (Stock No. 007913); however, homozygous fertility has not been evaluated on the C57BL/6J-congenic background. Restricted to the cytoplasm, CreER can only gain access to the nuclear compartment after exposure to tamoxifen. When Gli1-CreER mice are bred with mice containing a loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the flanked sequences in Gli1-expressing cells, making them useful for studying axis patterning, proliferation, and cell fate specification of Hedgehog responding cells at different stages of embryogenesis.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype of these C57BL/6J-congenic mice could vary from that originally described on a mixed genetic background. We may modify the strain description, if necessary, as published results become available.

Development

The Gli1-CreER^T2 targeting vector was designed by Dr. Alexandra Joyner, with a CreERT2 fusion gene (Cre-ER^T2; Cre recombinase fused to a G400V/M543A/L544A triple mutation of the human estrogen receptor ligand binding domain) followed by three tandem SV40 polyA sequence repeats and a reverse-oriented loxP-flanked neo cassette. This construct was inserted into the GLI-Kruppel family member GLI1 (Gli1) locus, replacing a 2.3 kb region including the ATG site in exon 2 and first zinc finger domain in exon 4. The target construct was introduced via electroporation into 129S6/SvEvTac-derived W4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric mice were bred to either Black-Swiss or C57BL/6J mice. The Gli1-CreER^T2 heterozygotes were then bred to cre expressing mice, on a Black-Swiss genetic background, to remove the neo cassette. The resulting Gli1-CreER^T2 offspring (with a single loxP site remaining after the SV40 polyA sequences) were bred to Swiss Webster outbred mice for many generations prior to arrival at The Jackson Laboratory as Stock No. 007913.

Dr. Robert Tighe acquired some Stock No. 007913 animals, on the mixed genetic background, and then backcrossed them at least 7 generations to C57BL/6J inbred mice (Stock No. 000664) before sending mice back to The Jackson Laboratory. The resulting C57BL/6J-congenic strain is called B6.Cg-Gli1^{tm3(cre/ERT2)Alj}/RtigJ, Stock No. 038495. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes.

Allele

Symbol: Gli1^{tm3(cre/ERT2)Alj}
Name: targeted mutation 3, Alexandra L Joyner
MGI accession ID: MGI:3053957
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible
Synonyms: Gli1^CreER; Gli1^CreERT2; Gli1^{tm3(cre/ERT2)Alj}; Gli1^{tm3(cre/ESR1)Alj}; Gli1-CreER^T2
Marker symbol: Gli1
Marker name: GLI-Kruppel family member GLI1
Marker synonyms: Gli; PAPA8; PPD1; Zfp5; Zfp-5
Chromosome: 10
Strain of origin: 129S6/SvEvTac
Expressed genes: cre/ERT2,Cre recombinase and estrogen receptor 1 (human) fusion gene,
Site of expression: tamoxifen-inducible cre activity is observed in cells that have received positive Hedgehog/Sonic Hedgehog signaling
Molecular note: CreERT2 cDNA and a floxed neo were inserted into the 5' UTR of the first coding exon. Crossing with mice expressing Cre removed the floxed neo. Cre expression in mice carrying this allele is induced by treating the mice with tamoxifen.