The Six2, sine oculis-related homeobox 2, gene encodes a transcription factor that is important in embryonic development, in particular, the maintenance of kidney nephron progenitors. Six2 is expressed in metanephric mesenchymal stem cells during kidney development and is not expressed in adult kidneys. In this inducible knock-in/knock-out Six2CE strain, Cre-ERT2 protein expression is driven by the endogenous Six2 promoter (a CreERT2 cassette replaced the initiation codon of Six2). Expression of the targeted Six2 is ablated and Cre activity is only detected upon treatment with tamoxifen, thereby offering both spatial and temporal control. Tamoxifen-inducible cre activity is observed in the developing kidney, head, ear and limb, mimicking the endogenous Six2 expression pattern.
Upon crossing these mice to Cre-reporter strains (e.g. floxed lacZ or GFP), Six2 expressing cells may be labeled for lineage tracing. 
Heterozygous mice are viable and fertile. Homozygotes are not viable, dying shortly after birth.

The Cre-ERT2 fusion protein consists of Cre recombinase fused to a triple mutant form of the human estrogen receptor which does not bind its natural ligand (17&beta;-estradiol) at physiological concentrations but will bind the synthetic estrogen receptor ligands 4-hydroxytamoxifen (OHT or tamoxifen) and, with lesser sensitivity, ICI 182780. Restricted to the cytoplasm, Cre-ERT2 can only gain access to the nuclear compartment after exposure to tamoxifen. To counteract the mixed estrogen agonist effects of tamoxifen injections, which can result in late fetal abortions in pregnant mice, progesterone may be coadministered.

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This Six2CE knock-in/knock-out allele was designed to both abolish expression of the Six2 gene and direct expression of the CreERT2 fusion protein from the Six2 promoter/enhancer elements. These mice are a Cre-lox tool that allows inducible Cre expression in Six2-expressing cells/tissues; including developing nephron progenitor cells.
 The donating investigator has also made available a Six2 knock-in/knock-out allele expressing an EGFP/CreERT2 fusion protein (Six2GCE ; Stock No. <a href="https://www.jax.org/strain/009600">009600</a>) and a BAC transgenic expressing an EGFP/Cre fusion protein (Six2-TGCtg ; Stock No. <a href="https://www.jax.org/strain/009606">009606</a>).

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Our minimum guarantee for cryorecovery orders is 2 carriers. To ensure that your colony can be rapidly expanded upon arrival, additional carriers may be added to your order.