Abstract
The discovery of the CRISPR-Cas9 endonuclease has enabled facile genome editing in living cells and organisms. Catalytically inactive Cas9 (dCas9) retains the ability to bind DNA in an RNA-guided fashion, and has additionally been explored as a tool for transcriptional modulation, epigenetic editing, and genome imaging. This Review highlights recent progress and challenges in the development of dCas9 for imaging genomic loci. The emergence and maturation of this technology offers the potential to answer mechanistic questions about chromosome dynamics and three-dimensional genome organization in vivo.