Cohesin bridging as a physical principle of enhancer-promoter communication

Central to genome function, enhancers are non-coding sequences that can control transcription from promoters hundreds of kilobases away. Yet the physical basis of this long-range communication remains unclear. A prevalent view is that enhancers activate promoters when the two elements come into spatial proximity through the 3D folding of chromatin. However, activation by spatial proximity alone has struggled to explain several core features of enhancer function. Here, we propose that the molecular motor cohesin transmits long-range enhancer action by forming bridges between enhancers and promoters during loop extrusion. In this view, rare and transient bridges carry regulatory communication,