Hi-C data from Drosophila melanogaster cell line Kc167 in different osmostress conditions.

Chromatin is organized into a 3D interwoven tapestry of multi-layer architectural features important for controlling gene expression. How distinct layers influence each other and quickly they quickly they respond to cellular environment is unclear. Using Hi-C in Drosophila melanogaster, we measure how 3D chromatin organization responds to cellular hyperosmotic stress. In combination with the hd-pairing method, we demonstrate that chromosome unpairing represents a fast an reversible response to hyperosmotic stress. We identify a novel function of the Z4 protein as an anti-pairer, which we demonstrate is necessary for changes to chromatin organization during hyperosmotic stress. Finally, we demonstrate how changes to pairing impacts the other interwoven layers of 3D chromatin organization. Hi-C samples from LacZ Isotonic, LacZ osmostress, LacZ Recovery, Z4KD Isotonic, Z4KD osmostress and Z4KD recovery groups, 2 replicates from each study group. First set of ChIP-seq data is from LacZ Isotonic immunoprecipitated with CAP-H2 antibody, LacZ Osmostress with CAP-H2 and Z4 antibodies, and Z4KD Isotonic with CAP-H2 antibody. Each group has 2 replicates. Second set of ChIP-seq data is from LacZ Osmostress and Z4KD immunoprecipitated with RNAPII antibody. Each group has 2 replicates. ATAC-seq data is from LacZ Isotonic and Z4KD Isotonic groups, each has 2 replicates.