Novel ROSA26 Cre-reporter Knock-in C57BL/6N Mice Exhibiting Green Emission before and Red Emission after Cre-mediated Recombination

• Published in: Experimental Animals Vol. 62; no. 4; pp. 295 - 304
• Main Authors: Hasegawa, Yoshikazu, Daitoku, Yoko, Sekiguchi, Keito, Tanimoto, Yoko, Mizuno-Iijima, Saori, Mizuno, Seiya, Kajiwara, Noriko, Ema, Masatsugu, Miwa, Yoshihiro, Mekada, Kazuyuki, Yoshiki, Atsushi, Takahashi, Satoru, Sugiyama, Fumihiro, Yagami, Ken-ichi
• Format: Journal Article
• Language: English
• Published: Japan Japanese Association for Laboratory Animal Science 01.01.2013
• Subjects: Animals; CAG promoter; Cells, Cultured; Cre-reporter mouse; EGFP; Embryonic Stem Cells; Endothelial Cells - metabolism; Female; Gene Expression; Gene Knock-In Techniques; Genes, Reporter - genetics; Genes, Reporter - physiology; Green Fluorescent Proteins - metabolism; Integrases - genetics; Integrases - metabolism; Islets of Langerhans - metabolism; Luminescent Proteins; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Original; Recombination, Genetic; Red Fluorescent Protein; Rosa26; tdsRed; Ubiquitination
• ISSN: 1341-1357; 1881-7122
• DOI: 10.1538/expanim.62.295

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 Cre-reporter 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/).