University of Virginia Health System

Email Address: ang3x@virginia.edu

The platelet producing cells in the bone marrow, megakaryocytes, develop from a precursor cell that also gives rise to red blood cells.  The genetic programming events that dictate the development of megakaryocytes along a pathway different from the red blood cells remain poorly understood. Nevertheless, these programming events are clearly disrupted in some types of human leukemia and in several human disorders of platelet production. Previous work in our lab has identified two proteins, RUNX1 and GATA-1, as key players in programming megakaryocyte development.  These two proteins communicate with one another in this process using a novel signaling mechanism involving an enzyme known as Cdk9.  Future experiments will provide a detailed understanding of how RUNX1, GATA-1, and Cdk9 cooperate in programming megakaryocyte development in mice and in human marrow cells. Importantly, several drugs currently in human trials are known to affect Cdk9 function and could profoundly influence megakaryocyte development.

Iron deficiency represents a frequent cause of anemia and causes the bone marrow to decrease production of red blood cells.  In addition to iron deficiency anemia, anemias associated with cancer, kidney disease, chronic inflammation, and aging also are associated with impaired red cell production by the bone marrow.  These latter anemias arise in part because of inadequate transport of iron from storage cells to the red cell precursors in the marrow.  In particular, red cell precursors sense an iron deficiency even though total body iron stores are frequently increased. This project has identified the mechanisms by which bone marrow cells sense iron availability and adjust red cell production accordingly.  Preliminary studies have led to compounds which can either reverse or mimic the response of marrow cells to diminished iron availability.  These studies therefore offer novel approaches for the treatment of several types of chronic anemia and for the treatment of diseases associated with excessive red cell production such as polycythemia.