The Drosophila VEGF receptor homolog is expressed in hemocytes

Abstract

Several signalling pathways have been defined by studies of genes originally characterised in Drosophila. However, some mammalian signalling systems have so far escaped discovery in the fly. Here, we describe the identification and characterisation of fly homologs for the mammalian vascular endothelial growth factor/platelet derived growth factor (VEGF/PDGF) and the VEGF receptor. The Drosophila factor (DmVEGF-1) gene has two splice variants and is expressed during all stages, the signal distribution during embryogenesis being ubiquitous. The receptor (DmVEGFR) gene has several splice variants; the variations affecting only the extracellular domain. The most prominent form is expressed in cells of the embryonic haematopoietic cell lineage, starting in the mesodermal area of the head around stage 10 of embryogenesis. Expression persists in hemocytes as embryonic development proceeds and the cells migrate posteriorly. In a fly strain carrying a deletion uncovering the DmVEGFR gene, hemocytes are still present, but their migration is hampered and the hemocytes remain mainly in the anterior end close to their origin. These data suggest that the VEGF/PDGF signalling system may regulate the migration of the Drosophila embryonic haemocyte precursor cells.

An Ancient Role for a Prokineticin Domain in Invertebrate Hematopoiesis

“…This cytokine, astakine, has structural similarities with vertebrate PK, such as endocrine gland-derived VEGF (EG-VEGF) (19 -23), and thus, our finding may shed new light upon the evolution of blood cells and vascular endothelial cells from invertebrates to vertebrates. In Drosophila, the VEGFR homologue is expressed in hemocytes and is involved in the early migration of plasmatocytes into areas of ligand-expressing cells in the embryo (24,25), in a similar manner as vertebrate VEGF (26). In addition, this receptor was shown to function in antiapoptotic hemocyte survival during embryogenesis (27).…”

A directed screen for genes involved in Drosophila blood cell activation

“…A proliferative response to this receptor is not unexpected, because Munier et al (13) showed that Pvr protein is expressed on the hemocyte surface and that overexpression of one of its putative ligands, Pvf2, induces a dramatic increase of the number of circulating hemocytes. Pvf2 also has been shown to be necessary for control of hemocyte migration in embryos (38,39).…”

Identification and Characterization of Genes Involved in Embryonic Crystal Cell Formation During Drosophila Hematopoiesis

“…Similarly, the AML-1, is necessary for crystal cell development during embryonic and larval hematopoiesis (Daga et al 1996; Drosophila platelet-derived growth factor and VEGFreceptor-related (PVR) protein is expressed in hemo- Lebestky et al 2000). lz has been shown to function downstream of srp; however, additional interactions becytes and is required for the proper migration (Heino et al 2001;Cho et al 2002) and survival (Brü ckner et tween these transcription factors initiate hemocyte commitment to the crystal cell lineage (Fossett et al 2003;al. 2004) and mapped by the Drosophila Genome Project, cov-…”