Chromatin loop dynamics during cellular differentiation are associated with changes to both anchor and internal...

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Background:

• Three-dimensional (3D) chromatin structure regulates gene transcription during biological transitions.
• Understanding the mechanisms of differential chromatin looping and its impact on gene transcription is limited by data availability.

Purpose of the Study:

• To investigate the mechanisms driving changes in chromatin looping during megakaryocyte development.
• To identify factors that correlate with differential looping and impact gene transcription.

Main Methods:

• Deeply sequenced Hi-C time course of megakaryocyte development with four biological replicates.
• Statistical analysis to identify differential loops and correlate them with epigenetic modifications and transcription factor binding.

Main Results:

• Identified 1503 differential loops during megakaryocyte development.
• Gained loop anchors showed enrichment for AP-1 occupancy and significant increases in histone H3K27ac.
• Changes in histone H3K27ac, chromatin accessibility, and JUN binding were strongly correlated with looping changes.

Conclusions:

• While CTCF and RAD21 are involved in loop formation, other features, including epigenetic modifications at loop boundaries, play a crucial role in regulating loop strength.
• Dynamic changes in chromatin looping are influenced by a combination of factors beyond core loop-forming machinery.