Tumor necrosis factor-alpha regulates expression of vascular endothelial growth factor receptor-2 and of its co-receptor neuropilin-1 in human vascular endothelial cells.
Tumor necrosis factor-alpha (TNF-alpha) modulates gene expression in endothelial cells and is angiogenic in vivo. TNF-alpha does not activate in vitro migration and proliferation of endothelium, and its angiogenic activity is elicited by synthesis of direct angiogenic inducers or of proteases. Here, we show that TNF-alpha up-regulates in a dose- and time-dependent manner the expression and the function of vascular endothelial growth factor receptor-2 (VEGFR-2) as well as the expression of its co-receptor neuropilin-1 in human endothelium. As inferred by nuclear run-on assay and transient expression of VEGFR-2 promoter-based reporter gene construct, the cytokine increased the transcription of the VEGFR-2 gene. Mithramycin, an inhibitor of binding of nuclear transcription factor Sp1 to the promoter consensus sequence, blocked activation of VEGFR-2, suggesting that the up-regulation of the receptor required Sp1 binding sites. TNF-alpha increased the cellular amounts of VEGFR-2 protein and tripled the high affinity 125I-VEGF-A165 capacity without affecting the Kd of ligand-receptor interaction. As a consequence, TNF-alpha enhanced the migration and the wound healing triggered by VEGF-A165. Since VEGFR-2 mediates angiogenic signals in endothelium, our data indicate that its up-regulation is another mechanism by which TNF-alpha is angiogenic and may provide insight into the mechanism of neovascularization as occurs in TNF-alpha-mediated pathological settings.
Vascular Biology Laboratory, Department of Genetics, Biology and Biochemistry, Medical School, University of Torino, Torino, 10126 Italy.
E
E
Giraudo
L
L
Primo
E
E
Audero
H P
HP
Gerber
P
P
Koolwijk
S
S
Soker
M
M
Klagsbrun
N
N
Ferrara
F
F
Bussolino
D000954:Antigens, Surface / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D039942:Neuropilin-1; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D015854:Up-Regulation; D014945:Wound Healing
D000954:Antigens, Surface; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D014409:Tumor Necrosis Factor-alpha; D039942:Neuropilin-1; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor