Sox17^CreERT2 mice may be used either to track Sox17-expressing cells or their progeny or to conditionally inactivate genes in Sox17-expressing cells at specific time points by tamoxifen injection. This line is complementary to Sox17-CreGFP and may avoid possible interferences of expression in the extra-embryonic visceral endoderm. We plan to analyze the effects of a direct activation/deletion of the Wnt pathway in the endoderm by crossing the Sox17-CreERT2 with the gain- and loss-of-function of β-catenin.

pSox17.LCA e targeting vector contains 10.288 kb 5’ arm and 4.525 kb5 3’arm.  Lox66 and Lox2272 sites are inserted flanking PuTK selection marker for positive selection for targeting events with puromycin and negative selection for RMCE events with ganciclovir.

Through homologous recombination in ES cells, a 3.793 kb region of the mouse Sox17 gene was replaced by a floxed tk-neo cassette, a puromycin-(delta)thymidine kinase fusion gene driven by the mouse phosphoglycerol kinase promoter (pUdelta-TK) and a neomycin resistant gene driven by the bacterial EM7 promoter (EM7neo) flanked by minimal (34 bp) tandemly oriented lox71 and lox2272 sites (Cre-recombinase recognition sequences).

These mice are currently in development.

This plasmid was constructed to insert, using recombinase-mediated cassette exchange, a 4103 bp fragment containing a CreERT2 fusion gene into the Sox17 gene locus thereby replacing the entire coding sequence of Sox17 gene. The Sox17-CreERT2 fragment was constructed by PCR amplification and insertion into the pBSL66-2272 plasmid with Not1 and Sal1. The sequencing of the PCR amplified fragment has revealed a mutation into the end of the Sox17-3’UTR. To facilitate positive selection of cassette-exchanged ES cells, a pgk-hygro selection cassette flanked by FRT sites was placed immediately downstream of the Sox17-CreERT2 fusion gene.