dCas9 Broadens the Application Scope of CRISPR

CRISPR/Cas9 is a popular gene editing tool that cleaves DNA using Cas9's endonuclease activity. Cas9 becomes inactive due to mutations in its RuvC and HNH domains, yet it still binds DNA with guide RNA to generate dCas9. By combining inhibitory/activating proteins with dCas9, CRISPRa/CRISPRi is generated, which modifies the chromatin at target enhancers and promoters to control the transcription of genes.