Transcription Factors Responsible for Megakaryocyte-Specific Gene Expression

Megakaryocytes are the hematopoietic precursors of platelets, which play an essential role in thrombosis and hemostasis. Platelet factor 4 (PF4) is expressed exclusively in megakaryocytes and platelets and serves as a lineage-specific marker of megakaryocytic differentiation. We previously characterized a number of upstream enhancer and repressor elements and demonstrated that GATA-1 and ETS-1 are important for PF4 gene expression. Recently, we have determined the novel regulatory element termed "TME" in the PF4 promoter and identified a group of binding proteins from megakaryocytic HEL cells. Here we review the function of these proteins in PF4 gene expression and discuss megakaryocyte-specific gene expression and megakaryocytepoiesis.