Enhancers reside in a unique epigenetic environment during early zebrafish development [ChIP-seq & ATAC-seq]. Danio rerio

We describe that during early zebrafish development, DNA methylation has little influence on enhancer activity, and that hypo-methylation is a unique feature of primed enhancers, whereas active enhancers are generally hyper-methylated. Hypo-methylated enhancers (hypo-enhancers) are enriched close to important transcription factors (TFs) that act later in development, are specifically de-methylated before the mid blastula transition (MBT), and reside in a unique epigenetic environment. Finally, we demonstrate that hypo-enhancers are functionally active later in development and that they are physically associated with the transcriptional start site (TSS) of target-genes, irrespective of target-gene activity. Overall design: we analyzed 5 novel ChIP-Seq libraries where we used the following AB (H3K27ac,H3K4me1,H3K4me2 and H3K27ac) and an Atac-Seq library.