Hematopoietic Development in Drosophila: A Parallel with Vertebrates

Abstract

D rosophila hematopoiesis includes two distinct phases. The first phase occurs during the second half of embryonic development, whereas the second hematopoietic phase occurs during the larval stages. Blood cells (hemocytes) are responsible mainly for phagocytosis, encapsulation of large invaders, and associated humoral melanisation reactions. The primary Drosophila hemocyte lineage is essentially akin to the mammalian myeloid lineage. In this review we describe the current knowledge of the molecular mechanisms that govern hemocyte proliferation and lineage specification while drawing parallels with mammalian hematopoiesis. A genetic hierarchy of four transcription factors regulates lineage specification. Mammalian homologs of three of these four transcription factors also have critical functions in mammalian hematopoiesis. In addition, as in mammalian hematopoiesis, signaling pathways (Toll-NF-κB, JAK-STAT and steroid hormone) and chromatin remodeling complexes regulate specific aspects of proliferation and differentiation in Drosophila hematopoiesis.