Advances in homology directed genetic engineering of human pluripotent and adult stem cells

Figure 4 Gene editing using Zinc finger nucleases. A: Schematic showing a zinc finger nuclease (ZFN) dimer bound to its target locus to introduce a site-specific double-stranded break (DSB) in the chromosome, each ZFN monomer consists of three to six zinc finger domains fused to the DNA-cleavage domain of the FokI endonuclease. B: The DNA DSB can be repaired via either the homologous recombination (HR), or C: the non-homologous end-joining pathway. HR requires a homologous DNA template to accurately repair DSBs in the chromosome, and ensures high fidelity DNA repair. In contrast, non-homologous end joining does not rely on sequence homology between the DNA ends for ligation and can be error-prone.