MOZ is essential for maintenance of hematopoietic stem cells

Monocytic leukemia zinc-finger protein (MOZ), a MYST family histone acetyltransferase, is involved in the chromosome translocations associated with acute myeloid leukemia. MOZ acts as a transcriptional coactivator for AML1, which is essential for establishment of definitive hematopoiesis. To investigate the roles of MOZ in normal hematopoiesis, we generated MOZ-null mice. MOZ(-/-) mice died around embryonic day 15 (E15). In MOZ(-/-) E14.5 embryos, hematopoietic stem cells, lineage-committed progenitors, and B lineage cells were severely reduced. On the other hand, arrest of erythroid maturation and elevated myeloid lineage populations were observed. MOZ-deficient fetal liver cells could not reconstitute hematopoiesis of recipients after transplantation. Analysis using microarray and flow cytometry revealed that expression of thrombopoietin receptor (c-Mpl), HoxA9, and c-Kit was down-regulated. These results show that MOZ is required for maintenance of hematopoietic stem cells, and that it plays a role in differentiation of erythroid and myeloid cells. Some aspects of the MOZ(-/-) phenotype are similar to that observed in PU.1-deficient mice. MOZ was able to interact with PU.1 and activate PU.1-dependent transcription, thus suggesting a physical and functional link between PU.1 and MOZ.