B6(129S4)-Et(icre)1555Rdav/J

Stock number: 009589
Strain synonyms: C57BL/6-Et(icre)1555Rdav/J
Research areas: Neurobiology Research, Research Tools

Description

These mice express a codon-improved Cre recombinase (iCre) gene under control of the promoter/enhancer regions surrounding the site where the enhancer trap transgene randomly inserted. These mice may be useful for generating conditional mutations for studying gain or loss of function and/or fate mapping in brain tissues.

Detailed description

Mice hemizygous for this enhancer trap transgene are viable and fertile, with expression of a codon-improved Cre recombinase (iCre) gene under control of the promoter/enhancer regions surrounding the site where the enhancer trap transgene randomly inserted. The donating investigator reports Cre recombinase activity in brain tissues (but may not have assessed expression in other tissues). When these enhancer trap transgenic mice are bred with mice containing a loxP-flanked sequence of interest, Cre-mediated recombination will result in deletion of the floxed sequence(s) in cre-expressing tissues in the offspring.

For characterization information, see images at the Allen Institute for Brain Science website (Et(icre)1555Rdav images).

Development

An enhancer trap transgenic approach was used to generate these mice. The TK-bgi-icre-bGHpA transgene was designed with a thymidine kinase minimal promoter, a beta-globin intron, an optimized variant of Cre recombinase (iCre; improved with mammalian codon usage, removed putative cryptic splice sites, altered stop codon, and reduced CpG content to limit the chances of epigenetic silencing in mammals), and a bovine growth hormone polyA signal. This transgene was injected into C57BL/6J embryos. Founder mice (F0) from line 1555 were bred to "C57 R26R" mutant mice from the Baylor College of Medicine (Gt(ROSA)26Sor^tm1Sor mice; similar to, but perhaps not as backcrossed as Stock No. 003474). The donating investigator reports that Cre-positive transgenic pups were bred to C57BL/6 mice or "C57 R26R" (see SNP note below) to maintain the colony. Upon arrival, transgenic mice were selectively bred to C57BL/6J inbred mice (Stock No. 000664) to remove the Gt(ROSA)26Sor^tm1Sor mutation.

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 1 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Et(icre)1555Rdav
Name: enhancer trap 1555, Ron Davis
MGI accession ID: MGI:3852350
Generation method: Transgenic
Attributes: Recombinase-expressing
Marker symbol: Et(icre)1555Rdav
Marker name: enhancer trap 1555, Ron Davis
Chromosome: UN
Strain of origin: C57BL/6J
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: Cre recombinase activity is observed in brain tissues
Molecular note: An enhancer trap transgenic approach was used to generate these mice. The TK-bgi-icre-bGHpA transgene was designed with the thymidine kinase minimal (TK) promoter minimal promoter driving a codon-improved cre recombinase sequence (icre). A beta globin intron separates the promoter from the cre gene and the bovine growth hormone polyadenylation signal follows the cre sequence. This transgene was injected into C57BL/6J embryos. Founder line 1555 was established on a C57BL/6J genetic background.