How To Make A Knock In Mouse

December 16, 2018
ingenious
Knockin

How To Make A Knock In Mouse

How To Make A Knock In Mouse by INGENIOUS

How Knock ins Are Made and How Much of an Impact They Have on Genetic Research

Knowing how to generate knock-in mice is one of the most important and sought out goals that amateur and professional researchers alike can pursue. Successfully creating a knock-in mouse model is considered a somewhat more difficult feat than that of generating knockout mice, despite the many different methods and scopes that are associated with the former. That being said, the differences between gene knockout and gene knock-in technologies are clearly defined and quite extensive. Knockout technologies use other tools aimed at deleting certain sections of the DNA sequence and targeting it as accurately as possible. Knock-ins, however, must be even more accurate due to the fact that they are designed to replace the information contained at a specific locus within the DNA sequence, or to add sequence information that cannot be found in that particular locus.

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There are many possible uses and protocols associated with generating a knock-in mouse. All methods of creating knock-in mice are designed to introduce an exogenous gene that typically has the function to break or modify endogenous genes in order to generate some sort of changes in the body at a genetic level. There are many types and uses for knock-in genes. One of them is the conventional knock-in mouse in which single or multiple point mutations are engineered or targeting your gene of interest with a cassette insertion to express an alternate sequence. Another option is to use the Cre/loxP system to generate an inducible gene expression, which is considered one of the most common methods of generating knock-in mice. The Rosa26 locus is also of paramount importance, as it can be used to generate ubiquitous gene expressions and a unique gene expression strategy. When the goal is to investigate the expression pattern of the gene and common methods might be difficult, there are other strategies that can be used. Combining with reporter proteins like mcherry and GFP, for example, is one of the best ways to achieve that goal. According to most experts, the production of knock-in mice is what typically requires the most advanced technology and research.

The process of generating a knock-in mouse is as elaborate as that of generating mouse knockouts. One of the most common methods of achieving this goal is through the use of homologous recombination. For that purpose, the production work must first involve the creation of a targeting vector, which is then electroporated into ES cells. Drug-resistant ES cell clones are identified and isolated, and then PCR screening is used on the homologous recombinant. After that, establishing recombinant ES clones will have to be properly supported through the production of chimeric mice and heterozygous mice. The production of F1 heterozygous mice is usually the last step in the process, requiring the mice to later be crossed and re-crossed with wild type mice, in order to remove the FLP or Cre transgene.

The possible applications of knock in mice and the knock in process in general are hard to fully estimate. For example, the knock in of human immunoglobin genes into mouse tissue has already proven its effectiveness. Another example is the modification of stem cells in humans for the purpose of achieving goals such as the correction of mutant gamma chain genes in hematopoietic stem cells. In conclusion, generating knockin mouse models is one of the most pressing research projects that scientists all around the world are trying to accomplish.

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