title: Antiangiogenic effect of soluble vascular endothelial growth factor receptor-1 in placental angiogenesis.
abstract: Differential splicing of the flt-1 mRNA generates soluble variant of vascular endothelial growth factor (VEGF) receptor-1 (sVEGFR-1, also known as sFlt-1). The action of VEGF is antagonized by sVEGFR-1. Soluble VEGFR-1 binds to VEGF with a high affinity and therefore works to modulate VEGF and VEGF signaling pathway. In this study, the authors tested the hypothesis that VEGF-mediated endothelial cell angiogenesis is tightly modulated by the release of sVEGFR-1 and placental expression of sVEGFR-1 is upregulated by hypoxia. Immunolocalization studies showed progressively intense staining for sVEGFR-1 and VEGF in the trophoblast of placental villous explants throughout gestation. Endothelial cell migration studies using a modified Boyden's chamber showed a significant increase in cell migration in response to VEGF that was significantly attenuated in the presence of exogenous sVEGFR-1. Furthermore, stimulation of endothelial cells with VEGF led to a dose-dependent increase in the release of sVEGFR-1 as determined by enzyme-linked immunosorbent assay (ELISA). Exposure of normal placental villous explants to hypoxia (1% pO2) increased trophoblast expression of sVEGFR-1 when compared with tissue normoxia (5% pO2). In addition, conditioned media from hypoxia treated placental villous explants induced a significant increase in endothelial cell migration that was significantly reduced in presence of sVEGFR-1. Our study demonstrates that hypoxia positively regulates sVEGFR-1 protein expression in ex vivo trophoblasts, which control VEGF-driven angiogenesis.
authors.affiliation: Department of Reproductive and Vascular Biology, The Medical School, University of Birmingham, Edgbaston, Birmingham, West Midlands, United Kingdom.
authors.forename: Shakil
authors.initials: S
authors.lastname: Ahmad
authors.forename: Asif
authors.initials: A
authors.lastname: Ahmed
mesh_terms: D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D018919:Neovascularization, Physiologic / Q000502:physiology*; D009924:Organ Culture Techniques; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1
chemical_list: D011506:Proteins; D042461:Vascular Endothelial Growth Factor A; C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1