Calcium Signaling Prompts NIPBL Recruitment at Active Enhancers and Promoters via Distinct Mechanisms to Reconstruct Genome Compartmentalization

During developmental progression the genomes of immune cells undergo large-scale changes in chromatin folding. However, insights into the signals and epigenetics that induce alterations in nuclear architecture remain rudimentary. Here, we found that calcium influx rapidly recruited the cohesin-loading factor NIPBL to thousands of binding sites to dictate widespread changes in compartment segregation. The induction of NIPBL-binding was coordinate with increased P300, BRG1 and RNA Polymerase II co-occupancy, via different kinetics at active enhancers and promoters. Through acute degradation system, we found that enhancers, rather than promoters, are dependent on BAF complexes to induce NIPBL recruitment. Finally, we found that calcium signaling acts universally to orchestrate rapid redistribution of NIPBL in both primary innate and adaptive immune cells. Collectively, these data reveal how calcium signaling regulates NIPBL occupancy to orchestrate nuclear architecture. Overall design: Performed in situ Hi-C, ChIP-Seq, GRO-Seq and ATAC-Seq to pinpoint the underlying molecular mechanisms by which calcium signaling modulates nuclear architecture.