Signalling properties of an HIV-encoded angiogenic peptide mimicking vascular endothelial growth factor activity

2001 ◽  
Vol 353 (3) ◽  
pp. 569-578 ◽  
Author(s):  
Patrick SCHEIDEGGER ◽  
Wolfgang WEIGLHOFER ◽  
Stéphanie SUAREZ ◽  
Sandra CONSOLE ◽  
Johannes WALTENBERGER ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Pharmacological Intervention ◽  
Vegf Receptor ◽  
Vascular Endothelial ◽  
Vegf Receptors ◽  
Basic Peptide ◽  
Hiv Tat ◽  
Endothelial Growth Factor

HIV-1 expresses a multifunctional protein called TAT (trans-acting transcriptional activator), the function of which in vivo is tightly correlated with the incidence of Kaposi's sarcoma in AIDS patients. TAT is angiogenic and apparently binds to receptors specific for vascular endothelial growth factor (VEGF). Amino acids 46–60 of HIV-TAT, known as the basic peptide, have been shown to be responsible for its functional interaction with VEGF receptors. To characterize further the binding properties of this peptide, its coding sequence was fused to the reading frame of bacterial thioredoxin, allowing the production of large amounts of chimaeric polypeptides in bacteria in a biologically active form. Binding of chimaeric proteins to VEGF receptors was studied in vitro in endothelial cell cultures expressing either of the two receptors. Chimaeric thioredoxin proteins carrying the basic domain of TAT bound to both VEGF receptors with affinities similar to those of HIV-TAT or VEGF. Interestingly, these polypeptides competed only partially with VEGF for receptor binding, implying different binding sites for the TAT peptide and VEGF. This suggests that TAT binds VEGF receptors at new sites that might be useful targets for pharmacological intervention during pathological angiogenesis. The thioredoxin/basic-peptide chimaeras are functional agonists that mediate VEGF receptor signalling: (1) they stimulate the growth of endothelial cells; (2) together with basic fibroblast growth factor they cause tube formation of endothelial cells in collagen gels; (3) they induce blood vessel formation on the chicken chorioallantoic membrane; and (4) they activate VEGF receptor kinase and mitogen-activated protein kinase activity.

scholarly journals Expression of vascular endothelial growth factor (VEGF) receptors in rat corpus luteum: regulation by oestradiol during mid-pregnancy

Reproduction ◽  
2001 ◽  
pp. 875-881 ◽  
Author(s):  
N Sugino ◽  
S Kashida ◽  
S Takiguchi ◽  
A Karube-Harada ◽  
H Kato
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Corpus Luteum ◽  
Vascular Endothelial Cells ◽  
Corpora Lutea ◽  
Vascular Endothelial ◽  
Vegf Receptors ◽  
Luteal Cells ◽  
Endothelial Growth Factor

The aim of this study was to investigate the expression of vascular endothelial growth factor (VEGF) receptors, the fms-like tyrosine kinase (flt-1) and kinase insert domain-containing region (KDR), in corpora lutea obtained at different stages of the oestrous cycle and during pregnancy in rats. Immunohistochemistry revealed that both flt-1 and KDR were localized in luteal cells in addition to vascular endothelial cells, and that the intensity of staining was stronger in pregnant rats than in cyclic rats. Rats undergoing hypophysectomy-hysterectomy on day 12 of pregnancy were treated with oestradiol until day 15 of pregnancy to determine whether oestradiol is involved in expression of flt-1 and KDR mRNA in the corpus luteum during mid-pregnancy. The flt-1 and KDR mRNA contents in the corpus luteum were decreased significantly by hypophysectomy-hysterectomy, and these decreases recovered significantly after oestradiol treatment. Changes in the mass of the corpus luteum and serum progesterone concentrations paralleled the changes in expression of flt-1 and KDR mRNA. Developmental studies indicated that flt-1 and KDR mRNA contents in the corpus luteum were constant until day 15 of pregnancy but decreased significantly on day 21 of pregnancy. In conclusion, both flt-1 and KDR were expressed in luteal cells in addition to vascular endothelial cells, and expression was upregulated by oestradiol during mid-pregnancy. flt-1 and KDR may play a role in development of the corpus luteum and in production of progesterone during mid-pregnancy in rats.

scholarly journals Localization of vascular endothelial growth factor (VEGF) receptors in normal and adenomatous pituitaries: detection of a non-endothelial function of VEGF in pituitary tumours

2006 ◽  
Vol 191 (1) ◽  
pp. 249-261 ◽  
Author(s):  
Chiara Onofri ◽  
Marily Theodoropoulou ◽  
Marco Losa ◽  
Eberhard Uhl ◽  
Manfred Lange ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Cell Proliferation ◽  
Endothelial Cells ◽  
Pituitary Adenoma ◽  
Growth Factor ◽  
Pituitary Adenomas ◽  
Vascular Endothelial ◽  
Vegf Receptors ◽  
Pituitary Tumours ◽  
Endothelial Growth Factor

As for any solid tumour, pituitary adenoma expansion is dependent on neovascularization through angiogenesis. In this process, vascular endothelial growth factor (VEGF) and its receptors VEGFR-1, VEGFR-2 and neuropilin-1 (NRP-1) may play an outstanding role. The intention of this work was to study the expression/localization and possible function of VEGF receptors in pituitary adenomas. VEGF receptor mRNA and protein expression was studied by in situ hybridization, immunohistochemistry and RT-PCR in 6 normal human pituitaries, 39 human pituitary adenomas and 4 rodent pituitary adenoma cell lines. VEGFR-1 expressing somatotroph MtT-S cells were used as a model to study the role of VEGF on cell proliferation and to elucidate the underlying mechanism of action. In normal pituitaries, VEGFR-1 was detected in endocrine cells, whereas VEGFR-2 and NRP-1 were exclusively expressed in endothelial cells. In pituitary tumours, a heterogeneous VEGFR expression pattern was observed by IHC. VEGFR-1, VEGFR-2 and NRP-1 were detected in 24, 18 and 17 adenomas respectively. In the adenomas, VEGFR-1 was expressed in epithelial tumour cells and VEGFR-2/NRP-1 in vessel endothelial cells. Functional studies in VEGFR-1-positive MtT-S cells showed that the ligands of VEGFR-1 significantly stimulated cell proliferation. This effect was mediated through the phosphatidylinositol-3-kinase-signalling pathway and involves induction of cyclin D1 and Bcl-2. Based on our results, we speculate that the ligands of VEGF receptors, such as VEGF-A and placenta growth factor, not only play a role in angiogenesis in pituitary adenomas, but also affect the growth of pituitary tumour cells through VEGFR-1.

scholarly journals Receptors of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in fetal and adult human kidney: localization and [125I]VEGF binding sites.

1998 ◽  
Vol 9 (6) ◽  
pp. 1032-1044 ◽  
Author(s):  
M Simon ◽  
W Röckl ◽  
C Hornig ◽  
E F Gröne ◽  
H Theis ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Binding Sites ◽  
Vegf Receptor ◽  
Vascular Endothelial ◽  
Placenta Growth Factor ◽  
Receptor Proteins ◽  
Adult Kidney ◽  
Endothelial Growth Factor

Vascular endothelial growth factor (VEGF) has an important function in renal vascular ontogenesis and is constitutively expressed in podocytes of the adult kidney. The ability of VEGF to be chemotactic for monocytes and to increase the activity of collagenase and plasminogen activator may have implications for renal development and renal disease. In humans, the cellular actions of VEGF depend on binding to two specific receptors: Flt-1 and KDR. The aims of this study were: (1) to localize VEGF receptor proteins in human renal ontogenesis; (2) to quantify VEGF binding in human fetal and adult kidney; and (3) to dissect the binding into its two known components: the KDR and Flt-1 receptors. The latter aim was achieved by competitive binding of VEGF and placenta growth factor-2, which only binds to Flt-1. Quantification of 125I-VEGF binding sites was performed by autoradiography and computerized densitometry. By double-label immunohistochemistry, VEGF receptor proteins were localized solely to endothelial cells of preglomerular vessels, glomeruli, and postglomerular vessels. In developing glomeruli, VEGF receptor protein appeared as soon as endothelial cells were positive for von Willebrand factor. Specific 125I-VEGF binding could be localized to renal arteries and veins, glomeruli, and the tubulointerstitial capillary network in different developmental stages. Affinity (Kd) of adult (aK) and fetal (fK) kidneys was: Kd: glomeruli 38.6 +/- 11.2 (aK, n = 5), 36.3 +/- 7.1 (fK, n = 5); cortical tubulointerstitium 19.4 +/- 2.6 (aK, n = 5), 11.6 +/- 7.0 (fK, n = 5) pmol. Placenta growth factor-2 displaced VEGF binding in all renal structures by approximately 60%. VEGF receptor proteins thus were found only in renal endothelial cells. A coexpression of both VEGF binding sites could be shown, with Flt-1 demonstrating the most abundant VEGF receptor binding sites in the kidney. These studies support the hypothesis of a function for VEGF in adult kidney that is independent of angiogenesis.

Neuropilin-1 regulates attachment in human endothelial cells independently of vascular endothelial growth factor receptor-2

Blood ◽  
2005 ◽  
Vol 105 (5) ◽  
pp. 1992-1999 ◽  
Author(s):  
Matilde Murga ◽  
Oscar Fernandez-Capetillo ◽  
Giovanna Tosato
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Endothelial Cell ◽  
Growth Factor ◽  
Critical Role ◽  
Vegf Receptor ◽  
Vascular Endothelial ◽  
Human Endothelial Cells ◽  
Neuropilin 1 ◽  
Endothelial Growth Factor

AbstractNeuropilin-1 (NRP-1) is a type 1 membrane protein that binds the axon guidance factors belonging to the class-3 semaforin family. In endothelial cells, NRP-1 serves as a co-receptor for vascular endothelial growth factor (VEGF) and regulates VEGF receptor 2 (VEGFR-2)–dependent angiogenesis. Although gene-targeting studies documenting embryonic lethality in NRP-1 null mice have demonstrated a critical role for NRP-1 in vascular development, the activities of NRP-1 in mature endothelial cells have been incompletely defined. Using RNA interference-mediated silencing of NRP-1 or VEGFR-2 in primary human endothelial cells, we confirm that NRP-1 modulates VEGFR-2 signaling-dependent mitogenic functions of VEGF. Importantly, we now show that NRP-1 regulates endothelial cell adhesion to extracellular matrix proteins independently of VEGFR-2. Based on its dual role as an enhancer of VEGF activity and a mediator of endothelial cell adhesiveness described here, NRP-1 emerges as a promising molecular target for the development of antiangiogenic drugs.

Vascular endothelial growth factor induces VE-cadherin tyrosine phosphorylation in endothelial cells

1998 ◽  
Vol 111 (13) ◽  
pp. 1853-1865 ◽  
Author(s):  
S. Esser ◽  
M.G. Lampugnani ◽  
M. Corada ◽  
E. Dejana ◽  
W. Risau
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Vascular Permeability ◽  
Tyrosine Phosphorylation ◽  
Adherens Junction ◽  
Vegf Receptor ◽  
Vascular Endothelial ◽  
Endothelial Growth Factor ◽  
Cell Cell

Interendothelial junctions play an important role in the regulation of endothelial functions, such as vasculogenesis, angiogenesis, and vascular permeability. In this paper we show that vascular endothelial growth factor (VEGF), a potent inducer of new blood vessels and vascular permeability in vivo, stimulated the migration of endothelial cells after artificial monolayer wounding and induced an increase in paracellular permeability of human umbilical vein endothelial cells (HUVECs). Furthermore, VEGF increased phosphotyrosine labeling at cell-cell contacts. Biochemical analyses revealed a strong induction of VEGF-receptor-2 (flk-1/KDR) tyrosine-autophosphorylation by VEGF which was maximal after 5 minutes and was followed by receptor downregulation. 15 minutes to 1 hour after VEGF stimulation the endothelial adherens junction components VE-cadherin, beta-catenin, plakoglobin, and p120 were maximally phosphorylated on tyrosine, while alpha-catenin was not modified. PECAM-1/CD31, another cell-cell junctional adhesive molecule, was tyrosine phosphorylated with similar kinetics in response to VEGF. In contrast, activation of VEGF-receptor-1 (Flt-1) by its specific ligand placenta growth factor (PlGF) had no effect on the tyrosine phosphorylation of cadherins and catenins. Despite the rapid and transient receptor activation and the subsequent tyrosine phosphorylation of adherens junction proteins the cadherin complex remained stable and associated with junctions. Our results demonstrate that the endothelial adherens junction is a downstream target of VEGFR-2 signaling and suggest that tyrosine phosphorylation of its components may be involved in the the loosening of cell-cell contacts in established vessels to modulate transendothelial permeability and to allow sprouting and cell migration during angiogenesis.

scholarly journals Regulation of the vascular endothelial growth factor (VEGF) receptor Flk-1/KDR by estradiol through VEGF in uterus

2006 ◽  
Vol 188 (1) ◽  
pp. 91-99 ◽  
Author(s):  
M A J Hervé ◽  
G Meduri ◽  
F G Petit ◽  
T S Domet ◽  
G Lazennec ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Receptor Expression ◽  
Maximal Response ◽  
Target Cells ◽  
Vegf Receptor ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Endothelial Growth Factor

The induction of vascular endothelial growth factor (VEGF) expression by 17β-estradiol (E2) in many target cells, including epithelial cells, fibroblasts and smooth muscle cells, suggests a role for this hormone in the modulation of angiogenesis and vascular permeability. We have already described a cyclic increase in Flk-1/KDR-expressing capillaries in the human endometrium during the proliferative and mid-secretory phases, strongly suggestive of an E2 effect on Flk-1/KDR expression in the endometrial capillaries. However, it is unclear whether these processes are due to a direct effect of E2 on endothelial cells. Using immunohistochemistry, we report an increase in Flk-1/KDR expression in endometrial capillaries of ovariectomized mice treated with E2, or both E2 and progesterone. This process is mediated through estrogen receptor (ER) activation. In vitro experiments using quantitative RT-PCR analysis demonstrate that Flk-1/KDR expression was not regulated by E2 in human endothelial cells from the microcirculation (HMEC-1) or macrocirculation (HUVEC), even in endothelial cells overexpressing ERα or ERβ after ER-mediated adenovirus infection. In contrast, Flk-1/KDR expression was up-regulated by VEGF itself, in a time- and dose-dependent manner, with the maximal response at 10 ng/ml. Thus, we suggest that E2 up-regulates Flk-1/KDR expression in vivo in endothelial cells mainly through the modulation of VEGF by a paracrine mechanism. It is currently unknown whether or not the endothelial origin might account for differences in the E2-modulation of VEGF receptor expression, particularly in relation to the vascular bed of sex steroid-responsive tissues.

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