Genome-wide map of transcription factor GATA1 occupancy during mitosis in G1E ER4+E2 cells

Tissue-specific transcription patterns are preserved throughout cell divisions to maintain lineage fidelity. We investigated whether transcription factor GATA1 plays a role in transmitting hematopoietic gene expression programs through mitosis when transcription is transiently silenced. Live cell imaging revealed that a fraction of GATA1 is retained focally within mitotic chromatin. ChIP-seq of highly purified mitotic cells uncovered that key hematopoietic regulatory genes are occupied by GATA1 in mitosis. The GATA1 co- regulators FOG1 and TAL1 dissociate from mitotic chromatin, suggesting that GATA1 functions as platform for their postmitotic recruitment. Mitotic GATA1 target genes tend to re-activate more rapidly upon entry into G1 than genes from which GATA1 dissociates. A novel system designed to destroy GATA1 specifically during mitosis revealed that mitotic occupancy is required for rapid target gene reactivation. These studies suggest a requirement of mitotic “bookmarking” by GATA1 for the faithful propagation of cell type-specific transcription programs through cell division