Creating and Maintaining Customized Knockout Mouse Models
The ability to modify the mouse genome has made genetically engineered knockout mice a powerful tool for modeling human disease. At Charles River, we help hundreds of customers globally on thousands of knockout mouse models, delivering study-ready cohorts to meet research needs.
Transgenic Mouse and Rat Model Creation
Learn more about CRISPR-Cas9* for genome editing, animal model creation, gene therapy, and modelling human disease by watching our webinar series.
Our scientific team works with industry partners who are leaders in the field of functional genomics and molecular engineering. Our combined in vitro and in vivo expertise provides the optimal environment for creating, characterizing, preserving, and distributing your mice.
Related Mouse Model Services We Offer
Types of Knockout Mouse Models We Work On
Constitutive Knockout Mice
This model is engineered to carry an inoperative gene. Usually, inactivation of the gene is achieved by the deletion (partial or total) of its sequence, and it is nonfunctional in the entire animal.
Conditional Knockout Mice
These knockout mice allow the deletion of a gene in a tissue- and/or time-specific manner. Often, the conditional KO mouse is achieved through the Cre-lox system. Instead of deleting the critical sequence, it is flanked by loxP sites (termed a floxed sequence). Cre recombinase deletes the sequence between two loxP sites. An inducible or tissue-specific Cre is used to knockout gene function in only that tissue.
RNAi Knockout Mice
RNA interference can reduce the expression of a target gene, without deleting it. Typically this is combined with conditional and/or inducible approaches to reduce expression of the target only under certain conditions in adult animals.
View the Transcript
00:12 There are thousands of genetically modified models. The human genome has about 20,000 protein coding genes, and there are sponsored efforts to knock out every one of those genes. It's estimated that about half of mice and rats used in research are genetically modified. To make a transgenic mouse, it used to take scientists about 12 to 18 months using the traditional techniques. With the latest techniques such as the CRISPR-Cas9 technology, it takes anywhere between three months to nine months. 01:15 CRISPR technology is a way where we can program a specific enzyme to cut anywhere in the genome. We can effectively cut and repair, and by doing so, it will create random mutations, or if we give it an actual donor template, it can incorporate that gene into the genome. 01:39 So Mirimus was formed in 2010. We entered the CRISPR arena shortly after the first publications came out in 2012. We had to jump on this technology because it was so exciting. I mean, the ability to cut the genome and modify it is a game changing in terms of model creation. 02:02 Charles River began partnering with Mirimus a couple of years ago, and the reason for the collaboration is that we have a complimentary set of core competencies. Our partners at Mirimus are experts in bioinformatics and genome editing technologies, and at Charles River, we have expertise in embryology and production breeding. By merging those two skill sets, we have created a unique service offering in which we bring model creation to our clients on an industrial scale. 02:36 So the types of models that you can create very rapidly with CRISPR are knockout models. You can cut two places in the genome and that gene will bind itself together and repair. And so by actually cutting in two places you've excised the gene. 02:53 If you actually want to create a knockin model, you can make a cut and actually deliver a template, and that template will be duplicated into the genome, thereby allowing you to modify and make any sort of designer gene that you would like. 03:07 The biggest challenges with CRISPR are that it's very easy to make a gene knockout. It's much, much more difficult to modify a gene and having a gene knocked in, so we're still trying to understand how it works precisely, so that we can get that to work much more efficiently. 03:25 CRISPR is moving at a speed unseen before. In every few weeks, you see more hundreds of papers coming out. I think we need to definitely keep up the speed in terms of trying to understand how CRISPR works to get it to work almost perfectly. 03:46 We do have to proceed cautiously. The side effects of editing a human genome may not be visible for many, many years, possibly even generations. Being careful is key, but proceeding is certainly justified seeing the benefits that this technology has brought. 04:10 I do believe that, in our lifetime, we will see diseases being cured. We should continue to use this technology to identify cure for diseases. And as long as we proceed with safety and ethics in mind, we should harness the power of this technique.
Frequently Asked Questions (FAQs) for Knockout Mice
What are some of the advantages of using knockout mouse models?
The gene knockout method is the simplest approach to reveal fundamental gene functions. Conditional knockout/inductible mice, inducible knockout mice, and knockdown mice can avoid the risk of a lethal phenotype associated with gene inactivation at earlier stages in development and allow for an analysis of gene inactivation effects on adult animals. Furthermore, as 65% of protein coding genes are likely pleiotropic, a conditional knockout mouse simplifies phenotyping analysis by focusing on a specific cell type.
Are there other project considerations?
Disrupting genes can sometimes result in compensation by other members of a multigene family. In these cases, multiple knockouts may be needed to obtain phenotypical effects (e.g., Hox genes). Moreover, it is possible that gene knockouts may fail to produce observable phenotypes in knockout mice, or may produce different characteristics from those observed in humans. Mouse background choice is an important consideration for better mimicking human phenotypes – ask our experts for further advice.
What are the methods used for generating a knockout mouse model?
Depending on your study and objectives, knockout mice can be obtained through:
- ES cell homologous recombination
- Genome-editing nucleases (e.g., CRISPR knockout)
- One-cell embryo direct injection
- ES cell modification
For further information on knockout mice, please see the IKMC (International Knockout Mouse Consortium) website.
The Science of Controlling CRISPR
With technologies like CRISPR gene editing accelerating at a rapid pace, what was once thought to be impossible to achieve with mice may become reality sooner than we ever imagined. The challenge will be to fully understand and control these new mouse model creation tools. For example: how does one limit off-target effects? What do we know about circular permutation, or inhibiting CRISPR with anti-CRISPRs? Read the full story
The CRISPR Potential in Accelerating Drug Development
CRISPR's comparative ease of use is expected to contribute to the development of more multifaceted cellular assays with improved predictability for drug therapies. Some of the benefits include reduced attrition rates of compounds and improved target validation.
Read the full story