An enhanced CRISPR repressor for targeted mammalian gene regulation

The RNA-guided endonuclease Cas9 can be converted into a programmable transcriptional repressor, yet inefficiencies in target gene silencing have limited its utility. Here we describe an improved Cas9 repressor based on the C-terminal fusion of a rationally designed bipartite repressor domain, KRAB-MeCP2, to nuclease-null Cas9. We demonstrate the system’s superiority in silencing coding and non-coding genes, simultaneously repressing a series of target genes, improving the results of single and dual gRNA library screens, and enabling new architectures of synthetic genetic circuits.