Traffic jam: gene transcription hampers cohesin’s travel along chromosomes

Cohesin is an assemblage of proteins that folds our chromosomes by extruding the DNA molecule into loops. This process can be slowed down or impeded by a number of proteins, but also by gene transcription. In a study now published in the journal PNAS, scientists at the IMP and MIT reveal that RNA polymerases, the main enzymes responsible for gene transcription, act as moving barriers to cohesin’s progression. They obstruct, slow down, and push cohesin away, thereby shaping the organisation of our genome.