Knock-out models can be roughly divided into conventional knock-out models and conditional knock-out models. Although conventional knock-outs offer a way to study gene function at a systematic level, many researchers choose a conditional knock-out approach instead due to their lethality risk and/or their limitations of analyzing a gene's role in the organogenesis of a particular tissue. With Cre/loxP technology, which is frequently used to create conditional knock-out models, however, these problems can be overcome or circumvented. Creative Biolabs is capable of providing different types of conditional knock-out models with both ESC/HR-based targeting strategies and nuclease-mediated gene editing technologies.
Below we have listed various conditional knock-out strategies:
Cre/LoxP System-based Targeting
Conditional knock-outs can be achieved with a chromosome site-specific recombinase system, such as Cre/LoxP, FLP/Frt, and Dre/Rox, among which Cre-LoxP system is the most frequently employed. Herein, the loxP sites, two 34 bp nucleotide sequences, are inserted around an essential exon in a gene and the region between these two loxP sites are excised by the Cre recombinase, which is derived from the P1 bacteriophage. As a result, mice that are phenotypically wildtype but containing the floxed allele in all tissues can be obtained. When mating with different Cre mice, tissue-specific or inducible knock-out mice are generated. Apart from the Cre/loxP technology, the Flp/Frt system and Dre/Rox are also two means of creating traditional knock-outs, less frequently used but still helpful. In brief, conditional models enable the study of gene inactivation in a specific cell type, tissue of interest, or at a defined developmental stage. Please click the links below for more detailed information of each type.
Tissue-Specific Knock-out Mice
A conditional type which inactivates gene expression in a specific target tissue. This type of model is often used to study the function of lethal genes, identify target gene of drugs, and evaluate drugs in preclinical studies.
This is a conditional knock-out model in which the expression of the target gene can be specifically inactivated in a time-controlled manner. Thus, the model expresses wild-type proteins and mutant proteins before and after induction, respectively. Especially, this model can be used in studies of diseases that are related to development or age.
CRISPR/Cas9-Based Targeting Strategy
Two components of sg RNA (crRNA and tracrRNA) targeting specific loci in the genome are designed and synthesized. The guide RNAs will guide Cas9 enzyme to the locus and cause DNA double strain break (DSB). Homologous recombination (HR) will enable the donor fragment which contains loxP (or frt) sites to integrate into the breaking locus.
In the meanwhile, Creative Biolabs offers other types of knock-out models that you may be interested in:
At Creative Biolabs, we have constructed systematic data and experience in this field and is happy to share our expertise with our clients. Contact or inquire us to discuss the ideal custom mouse model to boost the impact of your next project and beyond.
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