Large Transgene Knock-in Mouse Models
For decades, site-specific integration of large transgenes in mice has been possible using methods such as homologous recombination, and BAC-mediated random integration. These methods laid the foundation for advanced gene targeting in laboratory mice, but are weighed down with problems including but not limited to low efficiency, undesirable recombination outcomes, random insertion of the gene of interest, multiple copies of the gene, gene silencing and insertional mutations. These problems translate to more effort, require large colonies of animals, long turnaround times, and unpredictable deliverables.
An Integrase-based approach to generating transgenic mice, specifically the site-specific TARGATT™ φC31(PhiC31) integrase system, overcomes the above drawbacks and offers a method for site-specific integration with very high efficiency and dependability. The φC31 integrase catalyzes an irreversible recombination event between one or more tandem pseudo-attP sites that have been engineered into a preselected, safe harbor locus (Rosa26 or H11) in the mouse genome, and a donor vector containing the gene of interest and attP-recognition sequence, attB. The preselected loci are at intergenic regions on the chromosomes, which guarantees expression without causing positional effects or insertional mutations. This technology enables large transgene insertion (up to 22 kb) with very high efficiency (up to 40% or more), high site specificity, low incidence of position effect, and guaranteed expression of your transgene. This technology is ideal for generating mouse models for transgene overexpression, reporter genes, inducible/ conditional gene expression (such as by using a promoter-of-choice), and humanized mouse models.
Applied StemCell can also generate large transgene mouse models (up to 6 kb) using our highly optimized CRISPR/Cas9 technology, where your gene of interest can be inserted at a specific endogenous locus of choice, very efficiently and with fast turnaround time.