Figure 7.

Model of gene expression control by RUNX1 and TAL1 in MEPs and megakaryocytes centered on KLF1. (A) In MEPs, the expression of KLF1 is controlled by TAL1 and RUNX1. TAL1 has an activating role on KLF1 expression and on other erythroid genes such as the Globin genes and GYPA. In MEPs, TAL1 in conjunction with RUNX1 keeps KLF1 at a low level of expression. In MEPs, RUNX1 contributes to the intermediate epigenetic state of megakaryocytic genes such as CD41; as a consequence, they are expressed at a low level.²⁸ (B) In megakaryocytic cells, RUNX1 contributes to the repression of KLF1 expression. Simultaneously, RUNX1 activates megakaryocytic genes such as CD41. The activating role of KLF1 and TAL1 on erythroid genes is diminished, and the erythroid gene expression program is downregulated.