Novel ROSA26 Cre-reporter knock-in C57BL/6N mice exhibiting green emission before and red emission after Cre-mediated recombination

Y Hasegawa, Y Daitoku, K Sekiguchi… - Experimental …, 2013 - jstage.jst.go.jp
Y Hasegawa, Y Daitoku, K Sekiguchi, Y Tanimoto, S Mizuno-Iijima, S Mizuno, N Kajiwara…
Experimental animals, 2013jstage.jst.go.jp
The Cre/loxP system is a strategy for controlling temporal and/or spatial gene expression
through genome alteration in mice. As successful Cre/loxP genome alteration depends on
Cre-driver mice, Cre-reporter mice are essential for validation of Cre gene expression in
vivo. In most Crereporter mouse strains, although the presence of reporter product indicates
the expression of Cre recombinase, it has remained unclear whether a lack of reporter
signal indicates either no Cre recombinase expression or insufficient reporter gene promoter …
Abstract
The Cre/loxP system is a strategy for controlling temporal and/or spatial gene expression through genome alteration in mice. As successful Cre/loxP genome alteration depends on Cre-driver mice, Cre-reporter mice are essential for validation of Cre gene expression in vivo. In most Crereporter mouse strains, although the presence of reporter product indicates the expression of Cre recombinase, it has remained unclear whether a lack of reporter signal indicates either no Cre recombinase expression or insufficient reporter gene promoter activity. We produced a novel ROSA26 knock-in Cre-reporter C57BL/6N strain exhibiting green emission before and red after Cre-mediated recombination, designated as strain R26GRR. Ubiquitous green fluorescence and no red fluorescence were observed in R26GRR mice. To investigate the activation of tdsRed, EGFP-excised R26GRR, R26RR, mice were produced through the crossing of C57BL/6N mice with R26GRR/Ayu1-Cre F1 mice. R26RR mice showed extraordinarily strong red fluorescence in almost all tissues examined, suggesting ubiquitous activation of the second reporter in all tissues after Cre/loxP recombination. Moreover, endothelial cell lineage and pancreatic islet-specific expression of red fluorescence were detected in R26GRR/Tie2-Cre F1 mice and R26GRR/Ins1-Cre F1 mice, respectively. These results indicated that R26GRR mice are a useful novel Cre-reporter mouse strain. In addition, R26GRR mice with a pure C57BL/6N background represent a valuable source of green-to-red photoconvertible cells following Cre/loxP recombination for application in transplantation studies. The R26GRR mouse strain will be available from RIKEN BioResource Center (http://www. brc. riken. jp/lab/animal/en/).
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