Efficient Targeted DNA Methylation with dCas9-Coupled DNMT3A-DNMT3L Methyltransferase.

Epigenome editing is a powerful approach for the establishment of a chromatin environment with desired properties at a selected genomic locus, which is used to influence the transcription of target genes and to study properties and functions of gene regulatory elements. Targeted DNA methylation is one of the most often used types of epigenome editing, which typically aims for gene silencing by methylation of gene promoters. Here, we describe the design principles of EpiEditors for targeted DNA methylation and provide step-by-step guidelines for the realization of this approach. We focus on the dCas9 protein as the state-of-the-art DNA targeting module fused to 10×SunTag as the most frequently used system for editing enhancement. Further, we discuss different flavors of DNA methyltransferase modules used for this purpose including the most specific variants developed recently. Finally, we explain the principles of gRNA selection, outline the setup of the cell culture experiments, and briefly introduce the available options for the downstream DNA methylation data analysis.