Multiple Roles For The Zebrafish Homologue Of The Murine Evi1 Gene During Primitive Myelopoiesis And Hsc Development

The Evi1 locus was originally identified as a common site of retroviral integration in murine myeloid tumors. Several reports associate Evi1 expression with aggressiveness in myeloid leukemia. Since developmental pathways often reactivate in cancer, we hypothesized that Evi1 also plays critical roles during developmental hematopoiesis. Here, we employ the zebrafish model to study how evi1 modulates early blood development. We find that indeed zebrafish evi1 co-localizes with the hematopoietic markers scl, gata1, pu.1 and gata2 in the posterior lateral mesoderm and the rostral blood islands, indicating involvement in primitive hematopoiesis. Knockdown of evi1 via three independent Morpholino Oligonucleotides impairs embryonic myelopoiesis as shown by reduced pu.1, mpo and l-plastin staining, while not affecting hemangioblast formation and primitive erythropoiesis. Additionally, we observe reduced levels of cd41 expression upon evi1 knockdown, indicating that megakaryopoiesis is also impaired.