A Look at Conditional Knockout Mice and the Methods Used to Create Them
Conditional knockout mice play a critical role in genetics and biology research, because they allow scientists to manage how and when a specific gene is deleted. Genes can have different functions during an individual’s lifespan. Most dramatically, a gene may be essential for the proper development of an organism before birth, and then later in life can maintain a different function and influence the individual’s susceptibility towards a disease.
Techniques and technologies for creating conditional knockout mice continue to be developed, to help make the process more straightforward. By pairing conditional knockout mice with various existing Cre mouse lines, researchers are able to investigate many different gene knockout outcomes based on specific cells or tissues in which the gene has been deleted. In cases where an appropriate cell- or tissue-specific Cre mouse line does not already exist, researchers can develop their own custom Cre mouse line, which can then be shared with the research community as well.
What Is Conditional Knockout?
As a gene elimination process, the conditional knockout has many important uses when it comes to studying the role of particular genes in keeping the body in good health. Conditional gene knockout has to do with the controlled influence of the knockout process. This procedure is designed to help researchers target genes in specific tissues to render them inert. Conditional knockouts also eliminate the drawbacks and side effects of traditional knockout processes that eliminate genes from the entire body.
Techniques for Obtaining a Conditional Knockout Mouse
The Cre-lox recombination system is the most prevalent method used for obtaining conditional knockout mice. Recombination between two loxP sites is catalyzed by the Cre recombinase enzyme. This process causes the two recombining strands of DNA to exchange information and results in a deletion or an inversion between the two loxP sites. The Cre-lox system thus enables conditional gene knockout by the introduction of loxP sites into or surrounding the gene of interest and subsequent deletion of the loxP-flanked gene by tissue-specific Cre. To further advance the versatility of conditional knockouts, drug-inducible Cre enzymes have been developed, the most common of which is the tamoxifen-inducible CreERT2. By using inducible Cre enzymes, researchers are able to achieve both tissue-specific and temporal-specific knockout of the loxP-flanked gene.
Advanced Knockout Techniques and Technologies
While conditional gene knockout was not as prevalent several years ago, the conditional knockout process is receiving far more attention today than ever before. Companies and academic institutes involved with the study and creation of new knockout mice are also able to use newer, more advanced techniques such as CRISPR. As a result, these conditional mouse model systems help towards developing a greater variety of derivative mouse lines for studying gene function in biology and disease.
The Uses and Benefits of Conditional Knockout Mouse Models
What are conditional knockouts made for? The application of animal models that are developed using this methodology have to do with modeling human diseases accurately in other mammals – primarily in mice. Cancer is best studied with conditional knockout mouse models, due to the implication of somatic mutations in cancer development and progression, and also to allow researchers to study one specific type of cancer at a time. For example, conditional knockout models have been used to specifically study breast cancer.
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