Genome-Wide Quantitative Enhancer Activity Maps Identified by STARR-seq

The Regulatory Genome Multicellular organisms contain a variety of cell types that are morphologically and functionally distinct even though they typically contain the same genomic DNA. Differences stem from differential gene expression. Gene regulatory genomic regions (enhancers) are well studied, yet despite major efforts, such as Encode and modEncode, the number of enhancers in animal genomes and their genomic positions, cell-type specificity, and strengths are largely unknown. Arnold et al. (p. 1074 , published online 17 January) report a method, termed STARR-seq, that measures the strength of enhancers genome-wide, giving insight into the organization of the regulatory genome.