HOX HOMEOBOX GENES AS REGULATORS OF NORMAL AND LEUKEMIC HEMATOPOIESIS

Hox genes, first recognized for their role-in embryonic development, m ay also play Lineage-specific functions in a variety of somatic tissue s including the hematopoietic system. Expression of these transcriptio n factors has been demonstrated both in normal and leukemic human and hematopoietic cells, suggesting functional roles in hematopoietic cell growth and differentiation. Several recent studies have shown that Ho x proteins are involved in controlling proliferation of primitive bone marrow cells and also in altering differentiation of myeloid as well as lymphoid progenitors, alterations that also can contribute to leuke mic transformation. Hox genes, together with their upstream regulators and downstream target genes, may play key roles in fundamental proces ses-controlling hematopoietic stem cell properties.