Cell Biology Symposium: Zinc finger nucleases to create custom-designed modifications in the swine (Sus scrofa) genome.

Engineered zinc finger nucleases (ZFN) are rapidly gaining popularity as a means to enhance the rate and specificity of DNA modifications in plant and animal cells. Repair-mediated gene modification by ZFN is driven by introducing DNA double-strand breaks via a nonspecific nuclease domain linked to a sequence-specific zinc finger nucleotide recognition domain. This review examines the use of ZFN to produce genetically modified swine and the potential of this technology for the future. By combining conventional gene targeting methods with somatic cell nuclear transfer, several genetically modified pig models have been produced. These conventional techniques are inefficient in mammalian somatic cells and provide little control over the site specificity and rate of exogenous DNA integration. The use of engineered ZFN that bind and cleave genomic DNA at specific loci can enhance targeting efficiencies by orders of magnitude. Recent publication of the first genetic modification in pigs by combining ZFN technology with somatic cell nuclear transfer has opened the door to genome targeting with a precision that was not previously possible in a large animal model. Since that time, model pigs with selective knockout of endogenous genes have been produced. This review will examine the use of ZFN to generate these pig models and the potential of ZFN to accelerate the production of genetically modified pigs of agricultural and biomedical importance. Current methods of ZFN design, important considerations for their safe and effective use in modification of the swine genome, and future innovative applications of this technology in pigs will be discussed.