Rosa26-Cas9 knock-in mice have a CAG promoter directing the widespread expression cas9 and EGFP. EGFP fluorescence is widespread in brain, kidney, liver, spleen and heart tissue, and Cas9 protein is detected in whole brain. Analysis of multiple organs (including brain, kidney, liver, spleen, heart tissue) show that constitutive cas9 expression does not result in any detectable toxicity, morphological abnormalities, tumor formation, or up-regulation in DNA damage or apoptosis markers. Whereas gene editing via viral delivery of cas9 is burdened by packaging size limits, these Rosa26-Cas9 mice only require a specific single guide RNA (sgRNA) for generating single or multiple simultaneous mutations. Mice homozygous for the Rosa26-Cas9 knock-in allele on the STOCK and congenic C57BL/6J backgrounds are viable and fertile. Some mice have a white belly spot.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
Rosa26-Cas9 knock-in mice are also available on a C57BL6/NJ background (Stock No. 026430), on a FVB/NJ congenic background (Stock No. 026558), on a congenic NOD/ShiLtJ background (Stock No. 026557), as well as a STOCK background (Stock No. 024858).
