To study diseases that are based on a genetic alteration in the DNA, and to develop or improve therapeutic interventions requires realistic in vivo models that faithfully recapitulate the human condition. Genetically engineered mouse models (GEMMs) on a defined genetic background and of a defined microbiological status are an important and powerful tool.
- to generate new GEMMs by zygote injections.
- to generate new GEMMs by injection of modified embryonic stem cells into pre-implantation stage mouse embryos.
- to perform targeting of embryonic stem cells with your custom-made targeting constructs.
- to optimize the pluripotency of your commercially targeted clones by culturing them in specialized media.
- to generate complex, multigenic or multiple compound GEMMs by deriving GEMM-ESCs from existing GEMMs and combining it with the targeting of new, multiple genes and the use of RMCE.
- to produce and manage experimental cohorts for your studies.
To deliver proof of concept of these aims we launched, with others, project IMPAct (Innovative Mouse PlAtform). This initiative received an European grant and was realized in November 2014 by delivering multiple newly realized research models to the individual participants.
Generation of GEMM research models
Generation of GEMMs knows multiple approaches.
- Generation of 'gain of function' mutants, in which an additional gene is introduced in the genome and brought to overexpression, or in which a dominant negative version of the gene is brought to overexpression (fig. 1A). The injected gene or DNA of interest inserts in the genomic DNA as a random integration. The fact that the integration can take place anywhere in the genome and is not defined, is a major drawback. More advanced techniques are developed to ensure the integration takes place on a specific place (use of TALENs, ZFNs):
- Random transgenesis
- CRISPR/Cas genome editing.
- Generation of 'loss of function' mutants, in which
- the function of one or more genes is switched off permanently: constitutive knock-out model
- the function of a gene is switched off at a specific time or within a particular organ: conditional knock-out model - a gene has been replaced by a gene with a specific mutation or by a reporter gene that shows where and when it comes to gene expression: knock-in model
- a siRNA molecule expressed to ensure the function of a gene is temporarily neutralized: the knock-down model.
Generation of 'loss of function' mutants requires the use of embryonic stem cells (ES) and the technique of homologous recombination (interchanging the mouse-own gene by a in the molecular biology laboratory-made, mutated version of the gene) (fig. 1B).
- Generation of complex, multigenic GEMMs by derivation of embryonic stem cell lines (GEMM-ESCs) from established GEMMs and subsequent modification of additional alleles.
Contact our Sr. Scientist Transgenic Services to learn about our GEMM services at email@example.com