Mercury Chloride Impacts on the Development of Erythrocytes and Megakaryocytes in Mice

Inorganic mercury (Hg(2+)) is a highly toxic heavy metal. The aim of this study was to investigate the impact of Hg(2+) on the development of erythrocytes and megakaryocytes. B10.S mice (H-2(s)) and DBA/2 mice (H-2(d)) were administrated with 10 μM HgCl(2) or 50 μM HgCl(2) via drinking water for four weeks, and erythro-megakaryopoiesis was evaluated thereafter. The administration of 50 μM HgCl(2) increased the number of erythrocytes and platelets in B10.S mice, which was not due to a reduced clearance for mature erythrocytes. The administration of 50 μM HgCl(2), but not 10 μM HgCl(2), increased the number of progenitors for erythrocytes and megakaryocytes in the bone marrow (BM) of B10.S mice, including erythroid-megakaryocyte progenitors (EMPs), burst-forming unit-erythroid progenitors (BFU-Es), colony-forming unit-erythroid progenitors (CFU-Es), and megakaryocyte progenitors (MkPs). Moreover, 50 μM HgCl(2) caused EMPs to be more proliferative and possess an increased potential for differentiation into committed progenies in B10.S mice. Mechanistically, 50 μM HgCl(2) increased the expression of the erythropoietin receptor (EPOR) in EMPs, thus enhancing the Jak2/STAT5 signaling pathway to promote erythro-megakaryopoiesis in B10.S mice. Conversely, 50 μM HgCl(2) did not impact erythro-megakaryopoiesis in DBA/2 mice. This study may extend our current understanding for hematopoietic toxicology of Hg.