Journal: Molecular Therapy Nucleic Acids Publication year: 2020
The original application of the CRISPR/Cas9 system was to generate precisely targeted double-strand breaks that could be repaired by non-homologous end joining or by homology-directed repair when a suitable repair template was provided. Numerous tweaks to this initial system have led to a wide variety of additional applications. The focus of this paper is on the use of catalytically dead Cas9 (dCas9) fused to transcriptional activators, which can be recruited to specific genomic locations by single-guide RNAs to activate locus-specific transcription. The authors compare first-generation dCas9-VP64 and second-generation dCas9-SAM and dCas9-SunTag to induce gene expression in human pluripotent stem cells and human mesenchymal stem cells. The authors find that all systems induced specific and potent gene expression, but the 2nd-generation systems yielded higher and more consistent increases in expression of target genes.