Establishment of enhancer landscapes in hematopoietic cells revisited
A study from Patrick Matthias and his group at the FMI challenges a widely accepted model on how epigenome dynamics control the differentiation of hematopoietic cells. The plasticity of pluripotent stem cells was thought to be written in their genome in the form of a reduced heterochromatin prevalence and an abundance of "primed" regulatory regions (promoters and enhancers), from which the active elements to be used in later developmental stages are selected. Here, the authors show that early priming of enhancers and heterochromatin dynamics only play a minor role and that most active enhancers are generated de novo without involvement of these mechanisms. The study thus provides important novel insights into the dynamic regulation of the epigenome during hematopoiesis and possibly other systems.