Fig. 3

Use of epigenome editing tools to study the dynamics and memory of epigenetic regulation. a The selective recruitment of HP1α to specific loci in live cells was used to establish H3K9me3-dependent gene silencing and to study the kinetics and extent of heterochromatin. b In another study, doxycyline (DOX) was used to selectively recruit four repressive CRs that are associated with diverse chromatin modifications (Krüppel-associated box (KRAB) (associated with H3K9 methylation), embryonic ectoderm development (EED) (associated with H3K27 methylation), DNA methyltransferase 3B (DNMT3B) (associated with DNA methylation), and histone deacetylase 4 (HDAC4) (associated with histone deacetylation)). By tracking transcriptional output of a reporter gene in individual cells, researchers discovered that cells stochastically transition between active and silent states. These dynamics were described by a simple three-state model, in which different CRs operate over different time scales to modulate the fraction of cells in a population that are in each state. YFP yellow fluorescent protein