Capture-C reveals preformed chromatin interactions between HIF-binding sites and distant promoters

Hypoxia inducible factor (HIF) directs an extensive transcriptional cascade that transduces numerous adaptive responses to hypoxia. Pan-genomic analyses, using chromatin immunoprecipitation and transcript profiling, have revealed large numbers of HIF-binding sites that are generally associated with hypoxia-inducible transcripts, even over long chromosomal distances. However, these studies do not define the specific targets of HIF-binding sites and do not reveal how induction of HIF affects chromatin conformation over distantly connected functional elements. To address these questions we deployed a recently developed chromosome conformation assay that enables simultaneous high-resolution analyses from multiple viewpoints. These assays defined specific long-range interactions between intergenic HIF-binding regions and one or more promoters of hypoxia-inducible genes, revealing the existence of multiple enhancer-promoter, promoter-enhancer and enhancer-enhancer interactions. Overall design: We utilised Capture-C to study chromatin looping from distal HIF binding sites (enhancers) and the promoters of HIF regulated genes. Studying the dynamics in normoxia and hypoxia and across different cell types.