GSE210525
Regulation of cohesin loop extrusion underlies changes in enhancer-promoter interactions during pancreatic cell differentiation (Hi-ChIP)
Transcriptional reprogramming during cell fate determination involves precise targeting of enhancers to tissue-specific genes. Enhancer-promoter interactions are regulated by different types of 3D chromatin organization, including compartmental domains and CTCF loops. To understand the contribution of these different levels of chromatin organization in cell lineage commitment, we analyzed changes in 3D organization during the differentiation of human embryonic stem cells (hESCs) into pancreatic islet organoids. We find that major events in chromatin reorganization, including decompaction of transposon-enriched heterochromatin, breakdown of poised enhancer-promoter interaction networks, gain or loss of CTCF loops and establishment of novel enhancer-promoter contacts, occur either sequentially or simultaneously. Transcriptionally activated transposons released from unstable heterochromatin compartments recruit CTCF to form new loops. In contrast, when released from poised long-range interaction networks, enhancers and genes crucial for cell differentiation recruit tissue-specific transcription factors by either direct binding or indirect 3D contacts containing RNA Polymerase II. Activation of stage-specific genes correlates with gain of CTCF binding at anchors of extended CTCF loops, suggesting changes in loop extrusion capacity. In agreement with this, we find a global increase in cohesin loading leading to longer residency on extended CTCF loops encompassing tissue-specific genes. Our findings provide new insights into how distinct types of chromatin organization affect the reprogramming of gene expression patterns to regulate cell lineage commitment. Overall design: Hi-ChIP, Mi-ChIP