Arsenic impairs the lineage commitment of hematopoietic progenitor cells through the attenuation of GATA-2 DNA binding activity.

Arsenic exposure produces significant hematotoxicity in vitro and in vivo. Our previous work shows that arsenic (in the form of arsenite, AsIII) interacts with the zinc finger domains of GATA-1, inhibiting the function of this critical transcription factor, and resulting in the suppression of erythropoiesis. In addition to GATA-1, GATA-2 also plays a key role in the regulation of hematopoiesis. GATA-1 and GATA-2 have similar zinc finger domains (C4-type) that are structurally favorable for AsIII interactions. Taking this into consideration, we hypothesized that early stages of hematopoietic differentiation that are dependent on the function of GATA-2 may also be disrupted by AsIII exposure. We found that in vitro AsIII exposures disrupt the erythromegakaryocytic lineage commitment and differentiation of erythropoietin-stimulated primary mouse bone marrow hematopoietic progenitor cells (HPCs), producing an aberrant accumulation of cells in early stages of hematopoiesis and subsequent reduction of committed erythro-megakaryocyte progenitor cells. Arsenic significantly accumulated in the GATA-2 protein, causing the loss of zinc, and disruption of GATA-2 function, as measured by chromatin immunoprecipitation and the expression of GATA-2 responsive genes. Our results show that the attenuation of GATA-2 function is an important mechanism contributing to the aberrant lineage commitment and differentiation of early HPCs. Collectively, findings from the present study suggest that the AsIII-induced disruption of erythro-megakaryopoiesis may contribute to the onset and/or exacerbation of hematological disorders, such as anemia.