Issue link: http://life-technologies.uberflip.com/i/438554
8 Life Technologies ™ | Genome editing Genome editing is precise, site-specific DNA modification in a live cell. Genome editing involves the use of engineered nucleases, in conjunction with endogenous repair mechanisms, to insert, delete, or replace DNA sequences from a specific location in genomic DNA (Figure 1). The ability to edit the genome in a precise and targeted manner can be used to provide a more comprehensive understanding of biology and disease mechanisms. Genome editing has a variety of applications, such as creating disease-resistant transgenic plants, stem cell engineering, and gene therapy, and is also widely used in creating tissue and animal disease models. What is genome editing? Engineering made easy with engineered nucleases GENE DISRUPTION GENE INSERTION INVERSION GENE DELETION NON-HOMOLOGOUS END JOINING (NHEJ) Without added homologous DNA: repairs with indels GENE CORRECTION GENE ADDITION HOMOLOGY-DIRECTED REPAIR (HR) With added homologous DNA: insert/replace DNA Cell's repair mechanism is harnessed to heal DNA breaks CHROMOSOME & ENGINEERED NUCLEASE DNA-SPECIFIC DOUBLE-STRANDED BREAK Figure 1. Engineered nuclease-mediated genome editing. Engineered nucleases such as the CRISPR-Cas9 or TAL effectors can be designed to target specific sites in the genome, creating double-strand breaks (DSBs) at desired locations. The natural repair mechanisms of the cell repair the break by either homologous recombination (HR) or non- homologous end joining (NHEJ). HR is more precise, since it requires a template, allowing the introduction of foreign DNA into the target gene. Homologous DNA "donor sequences" can be used with homology-directed repair (HDR) to introduce a defined new DNA sequence. DSB repair by NHEJ is likely to introduce errors such as insertions or deletions (indels), leading to a nonfunctional gene.