What is the different between tissue-specific knockout mouse and an inducible knockout mouse
A tissue-specific knockout mouse and an inducible knockout mouse are both genetic tools used in scientific research to study the functions of specific genes. However, there are some key differences between them.
1. Tissue-specific knockout mouse: In this approach, a specific gene of interest is completely "knocked out" or deactivated in a specific tissue or cell type. This is achieved by using a tissue-specific promoter to drive the expression of an enzyme called Cre recombinase. The Cre recombinase enzyme then acts on special DNA sequences called loxP sites, which leads to the deletion of the targeted gene only in the tissues or cells where the tissue-specific promoter is active. This allows researchers to investigate the precise role of a specific gene in a particular tissue or cell type while leaving it intact in other tissues.
2. Inducible knockout mouse: Unlike tissue-specific knockout mice, inducible knockout mice allow the control of gene deletion in a temporal manner. This means that the targeted gene can be switched off at a specific time during development or even in adult mice. This is typically achieved by using a promoter that responds to specific external signals or chemicals, such as tamoxifen or tetracycline. When these inducers are administered, they activate the expression of the Cre recombinase enzyme, leading to the deletion of the targeted gene. This temporal control allows researchers to study the effects of gene deletion at specific developmental stages or under specific physiological conditions.
To generate and work with tissue-specific or inducible knockout mice, several steps are involved:
1. Gene targeting: The specific gene of interest is identified, and the DNA sequences needed to construct the knockout construct are determined.
2. Construct generation: The knockout construct, containing the tissue-specific promoter or the inducible element, is generated. This construct is typically introduced into embryonic stem cells using techniques like pronuclear injection or CRISPR/Cas9 gene editing.
3. Mouse generation: The embryonic stem cells with the knockout construct are used to generate transgenic mice. These mice inherit the knockout construct and can pass it on to their offspring.
4. Breeding strategy: The tissue-specific knockout mice or inducible knockout mice are bred with mice expressing the Cre recombinase enzyme to achieve targeted gene deletion in the appropriate tissues or in response to inducers. This breeding strategy ensures that the tissue-specific promoter or the inducible element is active in the desired tissues or at a specific time.
By using tissue-specific or inducible knockout mice, researchers gain valuable insights into the developmental, physiological, and functional roles of specific genes in a controlled and precise manner.