Enhancer Chromatin and 3D Genome Architecture Changes from Naive to Primed Human Embryonic Stem Cell States

Abstract

Summary: During mammalian embryogenesis, changes in morphology and gene expression are concurrent with epigenomic reprogramming. Using human embryonic stem cells representing the preimplantation blastocyst (naive) and postimplantation epiblast (primed), our data in 2iL/I/F naive cells demonstrate that a substantial portion of known human enhancers are premarked by H3K4me1, providing an enhanced open chromatin state in naive pluripotency. The 2iL/I/F enhancer repertoire occupies 9% of the genome, three times that of primed cells, and can exist in broad chromatin domains over 50 kb. Enhancer chromatin states are largely poised. Seventy-seven percent of 2iL/I/F enhancers are decommissioned in a stepwise manner as cells become primed. While primed topologically associating domains are largely unaltered upon differentiation, naive 2iL/I/F domains expand across primed boundaries, affecting three-dimensional genome architecture. Differential topologically associating domain edges coincide with 2iL/I/F H3K4me1 enrichment. Our results suggest that naive-derived 2iL/I/F cells have a unique chromatin landscape, which may reflect early embryogenesis. : Human ESCs grown in 2iL/I/F are useful for studying the transition from naive to primed pluripotency. Battle et al. show that the naive epigenome is globally enhanced for H3K4me1. Many of the H3K4me1 regions are putative enhancers and are lost, or decommissioned, during the transition to primed. Differential topologically associating domains (TADs) exist between states and contain H3K4me1 enrichment at TAD boundaries. Keywords: enhancers, 3D genome architecture, naive hESCs, embryogenesis