Fibroblast growth factor-2-mediated capillary morphogenesis of endothelial cells requires signals via Flt-1/vascular endothelial growth factor receptor-1: possible involvement of c-Akt.
Capillary morphogenesis is a crucial angiogenic response of endothelial cells. Although fibroblast growth factor-2 (FGF-2) potently induces capillary morphogenesis, the contribution of vascular endothelial growth factor-A (VEGF-A) in this response has not been clarified well. Here we examined the role of VEGF signaling in FGF-2-induced capillary morphogenesis by murine brain capillary endothelial cells (IBE cells) and human umbilical vein endothelial cells. FGF-2-treated IBE cells rapidly extended on Matrigel in association with actin reorganization. Chimeric protein, of which the extracellular domain of VEGF receptor-1 (VEGFR-1) fused to immunoglobulin Fc, inhibited FGF-2-induced cell extension, resulting in decreased capillary morphogenesis. Blocking antibody against VEGFR-1 inhibited FGF-2-induced capillary formation. Also, anti-VEGF-A antibody inhibited FGF-2-induced capillary morphogenesis, which was restored by the addition of placental growth factor-1. Similar results were obtained by the experiments with human umbilical vein endothelial cells. Expression of kinase-inactive c-Akt in IBE cells showed impaired capillary morphogenesis promoted by FGF-2. Conversely, stable cell lines expressing activated c-Akt demonstrated ligand-independent capillaries, which were resistant to the treatment with anti-VEGFR-1 blocking antibody. Upstream of c-Akt, calmodulin-dependent signals seemed to be involved. Taken together, signals via VEGFR-1 were required for FGF-2-induced capillary morphogenesis by endothelial cells, and c-Akt activity seemed to be involved in this process.
Kanda
Shigeru
S
Department of Molecular Microbiology and Immunology, Division of Endothelial Cell Biology, Nagasaki University Graduate School of Biomedical Science, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan. shigeruk@net.nagasaki-u.ac.jp
Miyata
Yasuyoshi
Y
Kanetake
Hiroshi
H
D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D002147:Calmodulin / Q000378:metabolism; D002196:Capillaries / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*
D019138:Antibodies, Blocking; D002147:Calmodulin; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D040281:Vascular Endothelial Growth Factor Receptor-1; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt