The transcriptional interactome: gene expression in 3D

Transcription in the eukaryotic nucleus has long been thought of as conforming to a model in which RNA polymerase complexes are recruited to and track along isolated templates. However, a more dynamic role for chromatin in transcriptional regulation is materializing: enhancer elements interact with promoters forming loops that often bridge considerable distances and genomic loci, even located on different chromosomes, undergo chromosomal associations. These associations amass to form an extensive ‘transcriptional interactome’, enacted at functional subnuclear compartments, to which genes dynamically relocate. The emerging view is that long-range chromosomal associations between genomic regions, and their repositioning in the three-dimensional space of the nucleus, are key contributors to the regulation of gene expression.