Simultaneous epigenomic profiling and regulatory activity measurement using e2MPRA.

Cis-regulatory elements (CREs) have a major effect on phenotypes including disease. They are identified in a genome-wide manner by analyzing the binding of transcription factors (TFs), various co-factors and histone modifications in DNA using assays such as ChIP-seq, Cut&Tag and ATAC-seq. However, these assays are descriptive and require high-throughput technologies, such as massively parallel reporter assays (MPRAs), to test the functional activity and variant effect on these sequences. Currently, technologies that can simultaneously analyze both the regulatory function of a specific sequence and the TFs, cofactors and epigenomic modifications that determine it do not exist. Here, we developed enrichment followed by epigenomic profiling MPRA (e2MPRA), a novel technology that utilizes lentivirus-based MPRA to enrich for the integration of specific CREs into the genome followed by Cut&Tag or ATAC-seq targeted specifically for these sequences. This method allows to simultaneously analyze in a high-throughput manner regulatory activity, protein binding and epigenetic modification of thousands of candidate CREs and their variants. We demonstrate that e2MPRA can be used to dissect the epigenetic functions of TF motifs arranged in synthetic enhancers, as well as to analyze the effect of enhancer sequence variants on epigenetic modifications. In summary, this technology will increase our understanding of the regulatory code, its effect on the epigenome and how its alteration can lead to a variety of phenotypes including human disease.