Rapid reversible changes in compartments and local chromatin organization revealed by hyperosmotic shock

• DOI: 10.1101/gr.238527.118
• Publication Date: 2018-12-06T21:11:29Z
• Authors: Ramon Amat; René Böttcher; François Le Dily; Enrique Vidal; Javier Quilez; Yasmina Cuartero; Miguel Beato; Eulàlia de Nadal; Francesc Posas
• Keywords: 0301 basic medicine; 03 medical and health sciences; Transcription, Genetic; Osmotic Pressure; Research; Humans; RNA Polymerase II; Chromatin Assembly and Disassembly; Chromatin; Cell Line

Nuclear architecture is decisive for the assembly of transcriptional responses. However, how chromosome organization is dynamically modulated to permit rapid and transient transcriptional changes in response to environmental challenges remains unclear. Here we show that hyperosmotic stress disrupts different levels of chromosome organization, ranging from A/B compartment changes to reduction in the number and insulation of topologically associating domains (TADs). Concomitantly, transcription is greatly affected, TAD borders weaken, and RNA Polymerase II runs off from hundreds of transcription end sites. Stress alters the binding profiles of architectural proteins, which explains the disappearance of local chromatin organization. These processes are dynamic, and cells rapidly reconstitute their default chromatin conformation after stress removal, uncovering an intrinsic organization. Transcription is not required for local chromatin reorganization, while compartment recovery is partially transcription-dependent. Thus, nuclear organization in mammalian cells can be rapidly modulated by environmental changes in a reversible manner.