A tissue-specific knock-out mouse model is defined as a model where a target gene is inactivated only in a specific tissue. In all other tissues, the target gene exhibits a functional expression. Technologies that can be used to create this subtype of conditional knock-out models include ESC/HR-based gene targeting strategy, CRISPR/Cas9 technique and TALEN technique. Equipped with all these latest technologies, Creative Biolabs is able to provide knock-out model services targeting genes in most tissue types including brain, intestine, muscles, skin and so on.
Cre/LoxP System-Based Targeting
Conditional knock-outs based on ESC/HR gene targeting strategy is mainly realized with a chromosome site-specific recombinase system, such as the Cre-LoxP system, FLP-Frt system, and the Dre-Rox system, etc. Taking the most commonly used approach, the Cre-LoxP system, for example. This system consists of two parts: the Floxed mouse where the gene of interest is flanked by two LoxP sequences, and the Cre transgenic mice responsible for excision of the gene sequence section between the two LoxP sites. By mating with different Cre mice, gene knock-out can be achieved in any tissues or cells of the mouse. Combined with the inducible system, which controls the expression of Cre recombinase, knock-outs at any developmental stage can be obtained. This model is often used to study the function of genes that exhibit a lethal phenotype, identify a drug target, and evaluate drugs in the preclinical phase.
Features of Tissue-Specific Gene Knock-out
One of the advantages of this strategy is that it can avoid the problems that are usually observed in conventional knock-out models, including embryonic lethal phenotypes resulting in no viable mouse, as well as a complex phenotype in which it is difficult to distinguish direct function in a particular tissue from secondary effects due to altered gene function in other tissues. In tissue-specific knock-outs, the phenotype tends to be more reliably related to the inactivation of the target gene. Moreover, besides tissue (cell) type, conditions like timing can also be controlled when inactivating a specific gene.
However, when designing the process of creating such a model, careful considerations and a thorough analysis are necessary in order to avoid down-regulated expression of the endogenous gene or truncated protein expression. Besides, there will be a longer timeline due to an extra breeding step with a Cre mouse used to delete the target gene.
CRISPR/Cas9-Based Targeting Strategy
Creative Biolabs is on the leading edge of the genetically engineered mice model creation field. With the latest CRISPR/Cas9 technology, virtually mouse model of any genetic background can be generated, either by microinjection or via CRISPR-based technology in ES cells, to satisfy every specific requirement of our clients.
In the meanwhile, Creative Biolabs offers other types of knock-out models that you may be interested in:
With the support of cutting-edge technologies and specialists in this field, Creative Biolabs is proud to offer the most reliable genome engineering model services at most favorable prices currently on the market. 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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