GRHL2 enhances phosphorylated estrogen receptor DNA-binding and regulates ER-mediated transcriptional activation and repression

Phosphorylation of estrogen receptor (ER) at serine 118 (pS118-ER) is induced by estrogen and is the most abundant post-translational mark associated with a transcriptionally active receptor. Cistromic analysis of pS118-ER from our group found enrichment of the GRHL2 motif near pS118-ER binding sites. In this report we use cistromic and transcriptomic analyses to interrogate the relationship between GRHL2 and pS118-ER. We found that GRHL2 is bound to chromatin at pS118-ER/GRHL2 co-occupancy sites prior to ligand treatment, and GRHL2 binding is required for maximal pS118-ER recruitment. pS118-ER/GRHL2 co-occupancy sites were enriched at active enhancers marked by H3K27ac and H3K4me1, along with FOXA1 and p300. Transcriptomic analysis yielded four subsets of ER/GRHL2 co-regulated genes revealing that GRHL2 can both enhance and antagonize E2-mediated ER transcriptional activity. Gene ontology analysis identified several coregulated genes involved in cell migration. Accordingly, knockdown of GRHL2 combined with estrogen treatment resulted in increased cell migration but no change in proliferation. These results support a model in which GRHL2 binds to select enhancers and facilitates pS118-ER recruitment to chromatin which then results in differential activation and repression of genes that control ER-positive breast cancer cell migration.