Lineage and stage specific expression of HOX 1 genes in the human hematopoietic system.

Recent observations have demonstrated the expression of several members of the homeobox-containing (HOX) gene complexes within the hematopoietic compartment. We have analyzed the expression pattern of the entire HOX 1 locus in a panel of leukemia-derived human cell lines representing various blood phenotypes. The expression of the eleven HOX 1 genes is lineage-restricted and these genes are predominantly detected within cells of myelomonocytic origin. This is in strong contrast with the erythro-megakaryocytic specific expression of HOX 2 genes. Furthermore, we have observed that the expression of three HOX 1 genes within B lymphoid lineages is stage-related and that the expression of several of them is switched off during TPA-induced differentiation of Kg1 and U937. These observations suggest that HOX 1 homeoproteins could be regulators of lineage determination during hematopoiesis.