SATB1 chromatin loops regulate Megakaryocyte/Erythroid Progenitor Expansion by facilitating HSP70 and GATA1 induction.

Diamond Blackfan Anemia (DBA) is an inherited bone marrow failure syndrome associated with severe anemia, congenital malformations and increased risk of developing cancer. The chromatin-binding SATB1 is downregulated in Megakaryocyte/Erythroid Progenitors (MEPs) in patients and cell models of DBA, leading to a reduction in MEP expansion. Here we demonstrate that SATB1 expression is required for the upregulation of the critical erythroid factors HSP70 and GATA1 that accompanies MEP differentiation. SATB1 binding to specific sites surrounding the HSP70 genes, promotes chromatin loops that are required for induction of HSP70, which in turn promotes GATA1 induction. This demonstrates that SATB1, although gradually downregulated during myelopoiesis, maintains a biological function in early myeloid progenitors.