Exonic enhancers are a widespread class of dual-function regulatory elements

This study aimed to interrogate enhancer activity within a custom library of 11,999 exons enhancers candidate regulatory sequences in the K-562 cell line using the STARR-seq approach. A library of 11,999 candidate enhancer sequences was cloned into a STARR-seq vector and transfected into K-562 cells in five replicates, with an empty-vector control. After 24 hours, total RNA and corresponding gDNA were isolated. Libraries were constructed from mRNA-derived cDNA and from gDNA, then sequenced to identify and quantify active regulatory sequences.