Technologies for Gene Engineering in Mammalian Cells
The NCI has entered into a collaborative agreement with Horizon Discovery, a UK company that holds the license for gene targeting in mammalian cell lines using recombinant adeno-associated virus (AAV). The press release can be viewed here. As part of the agreement, the Protein Expression Laboratory will serve as a center of excellence for production of reagents for gene targeting by NCI and NHGRI investigators. Coupling our expertise in clone construction using Gateway Multisite cloning and our experience in virus production and qualification, the PEL is well positioned to offer gene targeting services to investigators. Horizon scientists will assist in design of projects, and also offer advice for downstream screening of mutant cell lines. The PEL will generate targeting constructs and rAAV viruses, and can also do the initial transductions of cell lines for investigators. This technology can be used to make mutations, insertions, and deletions in any mammalian cell line and is highly robust and simple to use.
In addition to the AAV methodology, PEL is also developing reagents to use the TALEN double-strand endonuclease method for constructing modified mammalian cell lines. Similar to the popular ZFN approach, the TALEN technology uses a gene targeting approach in which the targeting efficiency is increased by a specific double-strand break at the desired site of homologous recombination. TALENs utilize a family of plant enzymes which bind a very specific DNA sequence using a dipeptide motif to read out sequence specificity, producing a highly efficient targeting with limited off-target effects. Current technology development efforts are underway to design reagents for this system and better understand the benefits and limitations of this new technology.