New routes for transgenesis of the mouse.

Transgenesis refers to the molecular genetic techniques for directing specific insertions, deletions and point mutations in the genome of germ cells in order to create genetically modified organisms (GMO). Genetic modification is becoming more practicable, efficient and predictable with the development and use of a variety of cell and molecular biology tools and DNA sequencing technologies. A collection of plasmidial and viral vectors, cell-type specific promoters, positive and negative selectable markers, reporter genes, drug-inducible Cre-loxP and Flp/FRT recombinase systems are available which ensure efficient transgenesis in the mouse. The technologies for the insertion and removal of genes by homologous-directed recombination in embryonic stem cells (ES) and generation of targeted gain- and loss-of function alleles have allowed the creation of thousands of mouse models of a variety of diseases. The engineered zinc finger nucleases (ZFNs) and small hairpin RNA-expressing constructs are novel tools with useful properties for gene knockout free of ES manipulation. In this review we briefly outline the different approaches and technologies for transgenesis as well as their advantages and disadvantages. We also present an overview on how the novel integrative mouse and human genomic databases and bioinformatics approaches have been used to understand genotype-phenotype relationships of hundreds of mutated and candidate disease genes in mouse models. The updating and continued improvements of the genomic technologies will eventually help us to unraveling the biological and pathological processes in such a way that they can be translated more efficiently from mouse to human and vise-versa.