Mouse Reporter Strain for Noninvasive Bioluminescent Imaging of Cells that have Undergone Cre-Mediated Recombination

Abstract

Conditional alleles containing LoxP recombination sites, in conjunction with Cre recombinase delivered by a variety of means, allows for spatial and temporal control of gene expression in mouse models. Here we describe a mouse strain in which a luciferase (Luc) cDNA, preceded by a LoxP-stop-LoxP (L-S-L) cassette, was introduced into the ubiquitously expressed ROSA26 locus. Mouse embryo fibroblasts derived from this strain expressed luciferase after Cre-mediated recombination in vitro. ROSA26 L-S-L-Luc/+ mice expressed luciferase in a diffuse or liver-restricted pattern, as determined by noninvasive, bioluminescent imaging, when crossed to transgenic mice in which Cre was under the control of a zygotically expressed (EIIA-Cre), or a liver-restricted (albumin-Cre), promoter, respectively. Organ-specific luciferase expression was also seen after intraparenchymal administration of an adenovirus encoding Cre. The ROSA26 L-S-L-Luc/+ strain should be useful for characterizing Cre mouse strains and for following the fate of cells that have undergone Cre-mediated recombination in vivo. Mol Imaging (2003) 2, 297 -302.

Assessing siRNA Pharmacodynamics in a Luciferase-expressing Mouse

“…In order to generate a mouse that ubiquitously expresses luciferase, we crossed male ROSA26-LSL-Luc and female Pb-Cre4 + mice 19,20. Pb-Cre4 + mice contain a Cre-recombinase transgene under control of the rat probasin promoter where expression is restricted to prostatic epithelium in male mice.…”

“…However, it has been documented that female mice which harbor the Pb-Cre4 transgene have ectopic expression of Cre-recombinase in oocytes 20. ROSA26-LSL-Luc mice are a strain in which a pGL3 luciferase complementary DNA preceded by a LoxP-Stop-LoxP (LSL) is inserted into the ubiquitously expressed ROSA26 locus 19. Using these two strains of mice we took advantage of the ectopic oocyte expression of Cre and crossed female mice containing the Pb-Cre4 transgene that were also homozygous for the ROSA26-LSL-Luc allele (R26-LSL-Luc fl/fl ) with male mice that were similarly positive for Pb-Cre4 + and R26-LSL-Luc fl/fl (Figure 1a).…”

“…We utilized the conditional activation of pGL3 luciferase from ROSA26-LSL-Luc mice developed by Safran et al 19 through ectopic expression of Cre-recombinase in oocytes under the control of the probasin promoter 20. We demonstrate that luciferase expression is detected in all tissues examined including lymphocytes which can be serially imaged over time when adoptively transferred into naive mice.…”

Gene Targeting in Embryonic Stem Cells, I

“…Another Cre-based inducible system is the loxP-stop-loxP technology (Safran et al, 2003). Basically, one or more floxed poly(A) addition signals are placed in the 5 0 untranslated sequence or in an early intron.…”

Imaging Mouse Cancer Models In Vivo Using Reporter Transgenes

“…Several laboratories have developed Cre-dependent reporters as an alternative way to achieve tumor-cell-specific reporter expression in GEM models (Lyons et al 2003;Safran et al 2003). Such mice possess a silent reporter transgene that has the ability to "switch on" and express in any cell of the body following Cre-mediated recombination.…”