Locus-associated R-loop repression in cis

Abstract R-loops exert varied beneficial or detrimental effects. To assess the function of an R-loop at a specific genetic locus, we had developed an inducible RNaseH1-EGFP-dCas9 (RED) protein chimaera as part of a locus-associated R-loop-modulating system (LasR). LasR is compatible with R-loop modulation in trans, which targets RED to one locus to repress R-loops at another spatially proximal site. Here we use the LasR system for R-loop modulation in cis, which consists of targeting RED directly to an R-loop. The combination of LasR in cis and trans will be essential to ascribe functions to specific R-loops within varied molecular contexts and study designs.