Effect of NKX2-5 or ETS1 on GATA4 pioneer activity [fibroblast]

GATA4 is a pioneer transcription factor. The mechanisms by which pioneer factors select and occupy specific loci, open chromatin, and activate enhancers is not well understood. To address the influence of partner, non-pioneer factors on pioneer factor activity, we analyzed the effect of NKX2-5 or ETS1 on GATA4 pioneer activity. NIH3T3 cells were transduced with lentivirus to obtain stable cell lines that express GFP (control), GATA4 (G), NKX2-5 (N), ETS1 (E), GATA4+NKX2-5 (GN), and GATA4+ETS1 (GE). We measured chromatin accessibility using ATAC-seq, and enhancer activation using H3K27ac. From these measurements we determined GATA4, GATA4+ETS, and GATA4+NKX2-5 pioneer binding, pioneer opening, and pioneer enhancer activation. Our results show that ETS1 or NKX2-5 alter GATA4 pioneer binding, opening, and enhancer activation. Overall design: NIH3T3 cells were transduced with lentivirus to obtain stable cell lines that express GFP (control), GATA4 (G), NKX2-5 (N), ETS1 (E), GATA4+NKX2-5 (GN), and GATA4+ETS1 (GE). We measured chromatin accessibility using ATAC-seq, and enhancer activation using H3K27ac. From these measurements we determined GATA4, GATA4+ETS, and GATA4+NKX2-5 pioneer binding, pioneer opening, and pioneer enhancer activation. We obtained three replicates per sample.