Human leukemia mutations corrupt but do not abrogate GATA-2 function.

Abstract

By inducing the generation and function of hematopoietic stem and progenitor cells, the master regulator of hematopoiesis GATA-2 controls the production of all blood cell types. Heterozygous <i>GATA2</i> mutations cause immunodeficiency, myelodysplastic syndrome, and acute myeloid leukemia. <i>GATA2</i> disease mutations commonly disrupt amino acid residues that mediate DNA binding or <i>cis</i>-elements within a vital <i>GATA2</i> intronic enhancer, suggesting a haploinsufficiency mechanism of pathogenesis. Mutations also occur in <i>GATA2</i> coding regions distinct from the DNA-binding carboxyl-terminal zinc finger (C-finger), including the amino-terminal zinc finger (N-finger), and N-finger function is not established. Whether distinct mutations differentially impact GATA-2 mechanisms is unknown. Here, we demonstrate that N-finger mutations decreased GATA-2 chromatin occupancy and attenuated target gene regulation. We developed a genetic complementation assay to quantify GATA-2 function in myeloid progenitor cells from <i>Gata2</i> -77 enhancer-mutant mice. GATA-2 complementation increased erythroid and myeloid differentiation. While GATA-2 disease mutants were not competent to induce erythroid differentiation of Lin^-Kit⁺ myeloid progenitors, unexpectedly, they promoted myeloid differentiation and proliferation. As the myelopoiesis-promoting activity of GATA-2 mutants exceeded that of GATA-2, <i>GATA2</i> disease mutations are not strictly inhibitory. Thus, we propose that the haploinsufficiency paradigm does not fully explain GATA-2-linked pathogenesis, and an amalgamation of qualitative and quantitative defects instigated by <i>GATA2</i> mutations underlies the complex phenotypes of GATA-2-dependent pathologies.