The H3K4 methyltransferase KMT2D is an essential cofactor for GATA1 at erythroid gene enhancers

Gene expression during cellular differentiation is coordinated by combinatorial interactions between transcription factors (TFs) and cofactors. Although the TF GATA1 coordinates gene transcription in hematopoiesis, the specific cofactors required for GATA1-driven gene expression are incompletely defined. We identify the H3K4 methyltransferase KMT2D, as a cofactor of GATA1 in erythropoiesis. Loss of KMT2D in human erythroid precursors causes developmental arrest with impaired expression of numerous erythroid genes. Mechanistically, KMT2D colocalizes with GATA1 on more than one thousand erythroid enhancers, and such co-occupancy is associated with stronger transcriptional activity than occupancy by GATA1 alone. Acute depletion of KMT2D in erythroid precursors causes rapid reductions of H3K4me1 and H3K27ac on a subset of GATA1-bound enhancers and impairs their target gene expression. Moreover, acute depletion of GATA1 or KMT2D individually causes downregulation of overlapping gene sets. Our findings demonstrate how a lineage-specific TF cooperates with a ubiquitous epigenetic regulator to drive lineage-specific gene expression. In this study, the authors identify KMT2D as a crucial cofactor for the transcription factor GATA1 in human erythropoiesis. KMT2D co-localizes with GATA1 on a subset of erythroid enhancers and is essential for their activation during erythroid differentiation.