GRHL2 Enhances Phosphorylated Estrogen Receptor (ER) Chromatin Binding and Regulates ER-Mediated Transcriptional Activation and Repression

ABSTRACT

Phosphorylation of estrogen receptor α (ER) at serine 118 (pS118-ER) is induced by estrogen and is the most abundant posttranslational mark associated with a transcriptionally active receptor. Cistromic analysis of pS118-ER from our group revealed enrichment of the GRHL2 motif near pS118-ER binding sites. In this study, we used 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, compared to sites where each factor binds independently. Transcriptomic analysis yielded four subsets of ER/GRHL2-coregulated genes revealing that GRHL2 can both enhance and antagonize E2-mediated ER transcriptional activity. Gene ontology analysis indicated that coregulated genes are 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 selected enhancers and facilitates pS118-ER recruitment to chromatin, which then results in differential activation and repression of genes that control estrogen-regulated ER-positive breast cancer cell migration.

KEYWORDS:

• DNA binding
• estrogen receptor
• GRHL2
• nuclear receptor
• transcription
• regulation of gene expression

Declaration of Interests

The authors declare no conflict of interest.

SUPPLEMENTAL MATERIAL

Supplemental material is available online only.

ACKNOWLEDGMENTS

We thank Kathryn Fox and the University of Wisconsin Carbone Comprehensive Cancer Center Flow Cytometry Laboratory for their assistance with proliferation studies. We thank Melissa Harrison, Elizabeth Larson, Tyler Gibson for their input into the CUT&RUN analysis. We also thank David Lung for his input into the manuscript.

This work is supported by NIH grant R01 CA260140 to E.T.A.