Recent advances in the CRISPR genome editing tool set

Genome editing took a dramatic turn with the development of the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins (Cas) system. The CRISPR-Cas system is functionally divided into classes 1 and 2 according to the composition of the effector genes. Class 2 consists of a single effector nuclease, and routine practice of genome editing has been achieved by the development of the Class 2 CRISPR-Cas system, which includes the type II, V, and VI CRISPR-Cas systems. Types II and V can be used for DNA editing, while type VI is employed for RNA editing. CRISPR techniques induce both qualitative and quantitative alterations in gene expression via the double-stranded breakage (DSB) repair pathway, base editing, transposase-dependent DNA integration, and gene regulation using the CRISPR-dCas or type VI CRISPR system. Despite significant technical improvements, technical challenges should be further addressed, including insufficient indel and HDR efficiency, off-target activity, the large size of Cas, PAM restrictions, and immune responses. If sophisticatedly refined, CRISPR technology will harness the process of DNA rewriting, which has potential applications in therapeutics, diagnostics, and biotechnology. Genome editing: Re-writing DNA Yong-Sam Kim and colleagues at Korea Research Institute of Bioscience and Biotechnology in Daejeon, South Korea, outline the latest developments in genome editing technologies and the limitations that remain. Although several approaches have been developed to make changes to an organism’s DNA at particular locations in the genome, the efficiency and simplicity of the CRISPR-Cas system, which plays a defense role in bacteria or archaea by chopping up the invaded DNA, has revolutionized the field. The authors review the different types of CRISPR system and explain how they induce quantitative or qualitative changes in gene expression in eukaryotic cells. Further improving the system’s DNA modification efficiency and the delivery of its components into cells, and finding ways to reduce off-target effects, will be required for CRISPR to realize its therapeutic potential.