Rodolphe Barrangou & Jennifer A Doudna

Nature Biotechnology (REVIEW); 8 SEPTEMBER 2016; VOLUME 34  NUMBER 9: 933-941 

Programmable DNA cleavage using CRISPR–Cas9 enables efficient, site-specific genome engineering in single cells and whole organisms. In the research arena, versatile CRISPR-enabled genome editing has been used in various ways, such as controlling transcription, modifying epigenomes, conducting genome-wide screens and imaging chromosomes. CRISPR systems are already being used to alleviate genetic disorders in animals and are likely to be employed soon in the clinic to treat human diseases of the eye and blood. Two clinical trials using CRISPR-Cas9 for targeted cancer therapies have been approved in China and the United States. 

Beyond biomedical applications, these tools are now being used to expedite crop and livestock breeding, engineer new antimicrobials and control disease-carrying insects with gene drives.

See http://www.nature.com/nbt/journal/v34/n9/full/nbt.3659.html

Figure 5  Genome editing redefined. This figure illustrates the range of applications based on CRISPR–Cas9 technologies. (i) Deletions (using HDR with a template in which a deletion is engineered). (ii) Insertions (by providing a HDR template carrying a designer sequence). (iii) Knockouts (using NHEJ-mediated DSB repair). (iv) Transcriptional activation (CRISPRa, using dCas9 tethered to a transcriptional activator, such as VP64). (v) Transcriptional repression (CRISPRi, using dCas9, potentially fused to a transcriptional repressor such as KRAB). (vi) Fusion protein delivery (by direct or indirect recruiting of an effector molecule of interest, through fusion, tethering, or by the use of guides carrying protein-binding DNA sequences of interest). (vii) Imaging (using fluorophores).  (viii) Epigenetic state alteration (using either epigenetic repressors such as the LSD1 histone demethylase for interaction with distal enhancers, or epigenetic activation using the p300 histone acetyltransferase).