GENETIC MANIPULATION OF GENOMES WITH RARE-CUTTING ENDONUCLEASES

DNA double-strand breaks (DSBs) pose a threat to the genomic integrity of a cell. The failure to heal a break or the inappropriate repair of a break can result in the loss of genetic information and other poten tially deleterious consequences, such as chromosomal translocations. R ecent developments using rare-cutting endonucleases have allowed inves tigators to introduce one or a few DSBs into complex genomes. Such stu dies have begun to elucidate the complex mechanisms of nonhomologous a nd homologous repair used by mammalian cells to repair these lesions. A key finding is that gene targeting is stimulated two to three orders of magnitude by a DSB at the target locus. Thus, the use of rare-cutt ing endonucleases and the co-opting of cellular repair mechanisms migh t provide scientists with another tool for engineering changes into ge nomes.