[Genome editing technology: from basics to applications].

ABSTRACT

The CRISPR/Cas9 system was initially discovered as a means of acquired immune response in bacterial species and has been developed and applied to genome editing technology in mammalian cells. This system consists of three key components crRNA, tracrRNA, and Cas9 protein. Once Cas9 is drawn to the target sequence, it creates DNA double-strand breaks, which then undergo repair via nonhomologous end joining or homology-directed repair. Thus, the CRISPR/Cas9 system enables us to knock out the gene of interest and insert the desired sequences for downstream analyses and clinical applications. Because of the simplicity of CRISPR/Cas9 technology, it has been widely adopted. For effective genome editing, several factors such as off-target effect and CRISPR/Cas9 delivery methods should be considered. Beyond gene knockout and nucleotide substitutions, CRISPR/Cas9 has been applied for various purposes, including more flexible nucleotide substitutions, transcriptional regulation, epigenetic modification, chromatin-chromatin interaction, and live-cell imaging using the nuclease domain deactivated mutant Cas9s, nCas9 and dCas9. This chapter discusses the expanding CRISPR/Cas9 technology-from basics to applications.