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Point Mutation Mouse Models


Precision targeting for your research.

Point mutation mouse models from ingenious allow you to study a known disease-causing mutation or alter a critical site from the murine to human sequence. Different strategies are available for creating point mutation mouse models depending on the experiments you have planned. No design is out of reach – our experienced staff will work with you to identify the best options for your gene of interest.

Conventional and Conditional Point Mutation Knockin Approaches

Conventional Point Mutation Knockin

A conventional point mutation results in the targeted allele encoding only the mutant sequence. This can be a powerful model for human disease, for example by changing a crucial codon to cause a deleterious amino acid substitution. If you want more control over expression of the mutant sequence in your point mutation mice, consider a conditional point mutation strategy, described below.

Conditional Point Mutation Knockin

Conditional point mutation mouse lines don’t express the mutant sequence until you choose to activate it. Your tissue-specific Cre-expressing mouse lines allow expression of the mutant gene only when or where Cre is active. Depending on your needs the allele can initially express the wild-type sequence or function as a null.  Use this to bypass the deleterious effects of your point mutation on embryonic development and create a model where you control the timing and location of activation.


Wildtype-First with Conditional Activation of Mutant

Advances in molecular biology and gene targeting now allow for generating animal models with the ability to “turn on” a point mutation in a specific tissue and/or at a specific time point. The gene will express as wild-type initially, until Cre recombinase is activated. Cre deletes the wild-type sequence and allows expression of the mutant sequence.

There is a lower risk of embryonic lethality or artificial phenotype since the mutation would be activated in only a specific tissue, or at a specific time point. Furthermore, a tissue or time specific mutation may more accurately reflect the disease of study. With the variety of Cre transgenic mouse lines available, multiple lines can be generated from the parental targeted mouse line, for expressing the mutant in different tissues or at specific times (CreERT2 or tetO-Cre can also be used for this). Thus the point mutation knockin mouse model is more versatile and can be utilized across scientific disciplines.

The following are two design examples on how this can be accomplished:

Point Mutation Knockin by Minigene Approach

Point Mutation Knockin by Inversion Approach

Knockout-First with Conditional Activation of Mutant

In some cases, our clients require more sophisticated mutation design options to allow for inducible expression of their mutation. One method that has been very successful and widely adapted is the use of removable transcription termination elements to control the expression of targeted alleles. Excision of the STOP cassette, and resulting expression of the mutant gene, is mediated by inducible and/or lineage specific recombinases (e.g., Cre or FLP), which allows spatial and temporal control of gene expression.

Diagram

After You Receive Your Mice: Mouse Colony Management

Frequently asked questions:

What is a point mutation example?

A good example of what a single point mutation can lead to happens in the case of converting the GAG codon into GUG. This would lead to the encoding of amino acid valine instead of glutamic acid.

RELATED: What Is A Point Mutation And Why Should You Know About It?

What is the difference between knockout and knock-in mice?

The processes for making knockin mice and knockout mice are similar in many ways and require special skills, tools, and reagents. A major difference in knockin vs knockout is that a knockout mutation is always targeted to a precise spot in the mouse’s genome.

RELATED: Difference Between Knock In And Knockout | ingenious

What happens in a point mutation?

A point mutation occurs in a gene when a single base pair is added, deleted or changed. While most point mutations are harmless, some can have various functional consequences, including changes in gene expression or alterations in encoded proteins which can lead to disease.

RELATED: Point Mutation – National Human Genome Research Institute

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