Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
J Biol Chem. 2013 Jul 12;288(28):20173-83. doi: 10.1074/jbc.M113.483818. Epub 2013 Jun 4.
Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) family members are essential and evolutionary conserved determinants of blood cell development and dispersal. In addition, VEGFs are integral to vascular growth and permeability with detrimental contributions to ischemic diseases and metastatic cancers. The PDGF/VEGF-receptor related (Pvr) protein is implicated in the migration and trophic maintenance of macrophage-like hemocytes in Drosophila melanogaster embryos. pvr mutants have a depleted hemocyte population and a breakdown in hemocyte distribution. Previous studies suggested redundant functions for the Pvr ligands, Pvf2 and Pvf3 in the regulation of hemocyte migration, proliferation, and size. However, the precise roles that Pvf2 and Pvf3 play in hematopoiesis remain unclear due to the lack of available mutants. To determine Pvf2 and Pvf3 functions in vivo, we generated a genomic deletion that simultaneously disrupts Pvf2 and Pvf3. From our studies, we identified contributions of Pvf2 and Pvf3 to the Pvr trophic maintenance of hemocytes. Furthermore, we uncovered a novel role for Pvfs in invasive migrations. We showed that Pvf2 and Pvf3 are not required for the directed migration of hemocytes, but act locally in epithelial cells to coordinate trans-epithelial migration of hemocytes. Our findings redefine Pvf roles in hemocyte migration and highlight novel Pvf roles in hemocyte invasive migration. These new parallels between the Pvr and PDGF/VEGF pathways extend the utility of the Drosophila embryonic system to dissect physiological and pathological roles of PDGF/VEGF-like growth factors.
血管内皮生长因子(VEGF)和血小板衍生生长因子(PDGF)家族成员是血细胞发育和扩散的必需且进化保守的决定因素。此外,VEGFs 对血管生长和通透性具有重要作用,对缺血性疾病和转移性癌症有不利影响。PDGF/VEGF 受体相关(Pvr)蛋白参与果蝇胚胎中巨噬细胞样血球的迁移和营养维持。pvr 突变体的血球数量减少,血球分布破裂。先前的研究表明,Pvr 配体 Pvf2 和 Pvf3 在调节血球迁移、增殖和大小方面具有冗余功能。然而,由于缺乏可用的突变体,Pvf2 和 Pvf3 在造血中的精确作用仍不清楚。为了确定 Pvf2 和 Pvf3 在体内的功能,我们生成了一个同时破坏 Pvf2 和 Pvf3 的基因组缺失。从我们的研究中,我们确定了 Pvf2 和 Pvf3 在 Pvr 营养维持血球中的作用。此外,我们发现了 Pvfs 在侵袭性迁移中的新作用。我们表明,Pvf2 和 Pvf3 不是血球定向迁移所必需的,但在上皮细胞中局部作用,协调血球的跨上皮迁移。我们的发现重新定义了 Pvf 在血球迁移中的作用,并强调了 Pvf 在血球侵袭性迁移中的新作用。Pvr 和 PDGF/VEGF 途径之间的这些新平行关系扩展了果蝇胚胎系统在剖析 PDGF/VEGF 样生长因子的生理和病理作用的用途。