The myriad biomolecules that regulate gene expression are governed by an unanticipated layer of control.

Researchers led by Richard Young at the Massachusetts Institute of Technology in Cambridge have found assemblies of enhancers — segments of DNA that associate with regulatory proteins and attach to genes to switch them on — that they have named super-enhancers. Compared with ordinary enhancers, super-enhancers bind to more proteins that activate gene transcription and are more sensitive to perturbation. The teams found that some cancer cells assemble pathological super-enhancers. Human cells contain tens of thousands of genes and many more enhancers, but most are controlled by only a few hundred super-enhancers that bestow characteristic properties on each cell type, the authors suggest.

Cell 153, 307–319; 320–334 (2013)