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Purpose: Vascular endothelial growth factor receptor 3 (VEGFR-3) plays a critical role in tumor lymphangiogenesis and metastasis, holding promise as a promising therapeutic target for solid tumors. TMVP1 (LARGR) is a 5-amino acid peptide previously identified in our laboratory from bacterial peptide display system that specifically targets VEGFR-3. Radiolabeled TMVP1 can be used for non-invasive imaging of VEGFR-3 expressing tumors. Homodimeric peptides have better targeting ability than monomeric peptides, and it is worth exploring whether homodimers of TMVP1 ((TMVP1) 2 ) can achieve better imaging effects. This study aimed to explore the peptide properties and tumor assessment value of [ 68 Ga]Ga-labeled (TMVP1) 2 ., Methods: In this study, we developed a TMVP1 homodimer that was conjugated with 1,4,7-triazacyclononane-N, N', N″-triacetic acid (NOTA) via tetraethyleneglycol (PEG 4 ) and triglyicine (Gly 3 ) spacer, and labeled with 68 Ga, to construct [ 68 Ga]Ga-NOTA-(TMVP1) 2 . Binding of VEGFR-3 by TMVP1 and (TMVP1) 2 , respectively, was modeled by molecular docking. The affinity of [ 68 Ga]Ga-NOTA-(TMVP1) 2 for VEGFR-3 and its ability to bind to cells were evaluated. MicroPET imaging and biodistribution studies of [ 68 Ga]Ga-NOTA-(TMVP1) 2 were performed in subcutaneous C33A cervical cancer xenografts. Five healthy volunteers and eight patients with cervical cancer underwent whole-body PET/CT acquisition 30-45 min after intravenous injection of [ 68 Ga]Ga-NOTA-(TMVP1) 2 ., Results: Both molecular docking and cellular experiments showed that homodimeric TMVP1 had a higher affinity for VEGFR-3 than monomeric TMVP1. [ 68 Ga]Ga-NOTA-(TMVP1) 2 was excreted mainly through the renal route and partly through the liver route. In mice bearing C33A xenografts, [ 68 Ga]Ga-NOTA-(TMVP1) 2 specifically localized in the tumor (2.32 ± 0.10% ID/g). Pretreatment of C33A xenograft mice with the unlabeled peptide NOTA-(TMVP1) 2 reduced the enrichment of [ 68 Ga]Ga-NOTA-(TMVP1) 2 in tumors (0.58 ± 0.01% ID/g). [ 68 Ga]Ga-NOTA-(TMVP1) 2 proved to be safe in all healthy volunteers and recruited patients, with no side effects or allergies noted. In cervical cancer patients, a majority of the [ 18 F]-FDG identified lesions (18/22, 81.8%) showed moderate to high signal intensity on [ 68 Ga]Ga-NOTA-(TMVP1) 2. SUVmax and SUVmean were 2.32 ± 0.77 and 1.61 ± 0.48, respectively. With normal muscle (gluteus maximus) as background, tumor-to-background ratios were 3.49 ± 1.32 and 3.95 ± 1.64 based on SUVmax and SUVmean, respectively., Conclusion: The favorable characterizations of [ 68 Ga]Ga-NOTA-(TMVP1) 2 such as convenient synthesis, high specific activity, and high tumor uptake enable the evaluation of VEGFR-3 in cervical cancer patients and warrant further clinical studies., Trial Registration: ChiCTR-DOD-17012458. Registered August 23, 2017 (retrospectively registered)., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Vascular endothelial growth factor receptor 2 (VEGFR-2) is known as one of the important antigens playing a vital role in angiogenesis. In this study, phage display technology (PDT) was used to produce a single-chain variable fragment (scFv) antibody against a region of the domain 3 in VEGFR-2 called kinase insert domain receptor 3 (KDR3). After designing the KDR3 peptide and biopanning, a colony was chosen for scFv antibody expression. Following expression and purification; western blotting, dot blotting and immunofluorescence (IF) were used to evaluate the antibody function. Surface plasmon resonance (SPR) was also employed to measure affinity of produced antibody. Once a colony was selected and transferred to the expression host, the scFv antibody was expressed in the expected range of 28 kDa. Using a designed chromatography column, antibody purification was found to be about 95%. In this study, a novel scFv with the capability of binding to KDR3 was isolated and purified and its intracellular function was investigated and verified.

The development of new lymphatic vessels occurs in many cancerous and inflammatory diseases through the binding of VEGF-C to its receptors, VEGFR-2 and VEGFR-3. The regulation of VEGFR-2/VEGFR-3 heterodimerisation and its downstream signaling in lymphatic endothelial cells (LECs) remain poorly understood. Here, we identify the endocytic receptor, uPARAP, as a partner of VEGFR-2 and VEGFR-3 that regulates their heterodimerisation. Genetic ablation of uPARAP leads to hyperbranched lymphatic vasculatures in pathological conditions without affecting concomitant angiogenesis. In vitro, uPARAP controls LEC migration in response to VEGF-C but not VEGF-A or VEGF-CCys156Ser. uPARAP restricts VEGFR-2/VEGFR-3 heterodimerisation and subsequent VEGFR-2-mediated phosphorylation and inactivation of Crk-II adaptor. uPARAP promotes VEGFR-3 signaling through the Crk-II/JNK/paxillin/Rac1 pathway. Pharmacological Rac1 inhibition in uPARAP knockout mice restores the wild-type phenotype. In summary, our study identifies a molecular regulator of lymphangiogenesis, and uncovers novel molecular features of VEGFR-2/VEGFR-3 crosstalk and downstream signaling during VEGF-C-driven LEC sprouting in pathological conditions.

The overexpression of VEGFR-3 is correlated with a worse prognosis in lung cancer and has been regarded as a rational target for specific drug delivery. Here, VEGFR-3 homing peptide library was efficiently established by computational design. Strong fluorescent signals of selected peptides were observed in A549 cells, but much weaker in other cells. The positive immunostaining overlapped with VEGFR-3 confirmed high affinity and selectivity of one novel peptide (CP-7). In addition, cell uptake of FITC-CP-7 peptide was significantly blocked by coinjection of excess CP-7 peptide. After labeled with 131 I, the profile of pharmacology and biodistribution could be traced in vivo. The 131 I-radiolabeled CP-7 peptide conjugates were >85% stable in serum over 4 h and exhibited a specific uptake of 18.04 ± 2.04% ID/g at 0.5 h after injection to high VEGFR-3 expressing A549 tumor mice. More importantly, lower uptake concentration in heart (1.06 ± 0.15% ID/g) after 2 h demonstrated the safety of peptide in vivo. The high uptake in the kidneys revealed that renal clearance was the main route of 131 I-CP-7 peptide elimination from the body. Lower accumulation of 131 I-CP-7 peptide in VEGFR-3 negative HeLa tumor mice further indicated that CP-7 peptide exhibited a higher tumor-homing efficiency. These studies provided a straightforward analytical access to design and screen bioactive peptide based on protein structure and revealed that CP-7 peptide represented a promising homing peptide of VEGFR-3-positive cancer in vitro and in vivo which could be used as a novel target molecule to achieve efficient drug delivery.

Members of the vascular endothelial growth factor receptor (VEGFR) family play a central role in angiogenesis as well as lymphangiogenesis and are crucial for tumor growth and metastasis. In particular, VEGFR-3 expression is induced in endothelial cells during tumor angiogenesis. We report the design of anticalins that specifically recognize the ligand-binding domains 1 and 2 of VEGFR-3. To this end, a library of the lipocalin 2 scaffold with 20 randomized positions distributed across its binding site was subjected to phage display selection and enzyme linked immunosorbent assay (ELISA) screening using the VEGF-C binding fragment (D1-2) or the entire extracellular region (D1-7) of VEGFR-3 as target proteins. Promising anticalin candidates were produced in Escherichia coli and biochemically characterized. Three variants with different receptor binding modes were identified, and two of them were optimized with regard to target affinity as well as folding efficiency. The resulting anticalins show dissociation constants down to the single-digit picomolar range. Specific recognition of VEGFR-3 on cells was demonstrated by immunofluorescence microscopy. Competitive binding versus VEGF-C was demonstrated for two of the anticalins with Ki values in the low nanomolar range. Based on these data, VEGFR-3 specific anticalins provide promising reagents for the diagnosis and/or therapeutic intervention of tumor-associated vessel growth.

Precondition for tumor lymphatic metastasis is that tumor cells induce formation of original and newborn lymphatic vessels and invade surrounding lymphatic vessels in tumor stroma, while some pathway-related molecules play an important role in mechanisms associated with proliferation and migration of lymphatic endothelial cells (LECs) and tumor cells. In lymphangiogenesis and lymphatic metastasis, the pathway-related molecules of VEGFC/D-VEGFR3/NRP2 axis, such as Furin-like enzyme, CNTN1, Prox1, LYVE-1, Podoplanin, SOX18, SDF1 and CXCR4, are direct constitutors as a portion of VEGFC/D-VEGFR3/NRP2 axis, and their biological activities rely on this ligand-receptor system. These axis-related signal molecules could gradually produce waterfall-like cascading effects, mediate differentiation and maturation of LECs, remodel original and neonatal lymphatic vessels, as well as ultimately promote tumor cell chemotaxis, migration, invasion and metastasis to lymphoid tracts. This review summarizes the structure and function features of pathway-related molecules of VEGFC/D-VEGFR3/NRP2 axis, the expression changes of these molecules in different anatomic organs or histopathologic types or development stages of various tumors, the characteristics of transduction, implementation, integration of signal networks, the interactive effects on biological behaviors between tumor cells and lymphatic endothelial cells, and their molecular mechanisms and significances in tumor lymphangiogenesis and lymphatic metastasis., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Type I diabetes, an autoimmune disease, induces insulin deficiency, which then disrupts vascular endothelial cell function, affecting blood and lymphatic vessels. Nitric oxide (NO) is an immune-induced destructive mediator in type I diabetes, and inhibition of its production promotes arteriosclerosis. In this study, lymphangiogenesis and expression of NO synthase (NOS) during the healing process after tooth extraction were investigated immunohistochemically in control (C57BL) and Akita mice as a diabetes model. Between 1, 4, and 10 days after extraction, expression of NOS, vascular endothelial growth factor-C (VEGF-C), VEGF receptor-3 (VEGFR-3), and von Willebrand factor was strongest during the granulation tissue phase. This suggests that severe inflammation triggers regulation of NOS and these other angiogenic and lymphangiogenic factors. During the callus phase, a few days after extraction, induced osteoblasts were positive for VEGF-C and VEGFR-3 in both the control and Akita mice, suggesting that bone formation is active in this period. Bone formation in the Akita group exceeded that in the controls. Bone tissue formation was disrupted under hyperglycemic conditions, however, suggesting that such activity would be insufficient to produce new bone.

We previously reported that neostatin, a proteolytic fragment of collagen XVIII that includes endostatin, inhibits basic fibroblast growth factor-induced corneal angiogenesis and lymphangiogenesis. In experiments to determine which fragments in neostatin are responsible for binding to VEGF receptors (VEGFRs), we previously showed that a 28- mer sequence at the C-terminal of endostatin, known as endostatin peptide 9, preferentially binds VEGFR3-Fc over VEGFR1-Fc and VEGFR2-Fc. In the present study, we show that a different endostatin fragment, endostatin peptide 4 (26 mers long), also selectively binds VEGFR3-Fc and not VEGFR1-Fc or VEGFR2-Fc. From surface plasmon resonance data, the KD and Chi² (RU²) values for endostatin peptide 4 binding to VEGFR3-Fc are 5.72 × 10⁻⁸ M and 0.354, respectively. In conclusion, endostatin peptides 4 and 9 may be responsible for endostatin binding to VEGFR3-Fc, and this improved understanding of endostatin peptide binding to VEGFR3-Fc may support the development of therapeutics targeting lymphangiogenic processes.

Focal adhesion kinase (FAK) and vascular endothelial growth factor receptor 3 (VEGFR3) are tyrosine kinases, which function as key modulators of survival and metastasis signals in cancer cells. Previously, we reported that small molecule chlorpyramine hydrochloride (C4) specifically targets the interaction between FAK and VEGFR3 and exhibits anti-tumor efficacy. In this study, we designed and synthesized a series of 1 (C4) analogs on the basis of structure activity relationship and molecular modeling. The resulting new compounds were evaluated for their binding to the FAT domain of FAK and anti-cancer activity. Amongst all tested analogs, compound 29 augmented anti-proliferative activity in multiple cancer cell lines with stronger binding to the FAT domain of FAK and disrupted the FAK-VEGFR3 interaction. In conclusion, we hope that this work will contribute to further studies of more potent and selective FAK-VEGFR3 protein-protein interaction inhibitors., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Vascular endothelial growth factor receptors (VEGFRs) in vertebrates play essential roles in the regulation of angiogenesis and lymphangiogenesis. VEGFRs belong to the receptor-type tyrosine kinase (RTK) supergene family. They consist of a ligand-binding region with seven immunoglobulin (7 Ig) -like domains, a trans-membrane (TM) domain, and a tyrosine kinase (TK) domain with a long kinase insert (KI) (also known as a type-V RTK). Structurally, VEGFRs are distantly related to the members of the M-colony stimulating factor receptor/platelet-derived growth factor receptor (CSFR)/(PDGFR) family, which have five immunoglobulin (5 Ig)-like domains. However, signal transduction in VEGFRs significantly differs from that in M-CSFR/PDGFRs. VEGFR2, the major signal transducer for angiogenesis, preferentially uses the phospholipase Cγ-protein kinase C (PLC-γ-PKC)-MAPK pathway, whereas M-CSFR/PDGFRs use the PI3 kinase-Ras-MAPK pathway for cell proliferation. In phylogenetic development, the VEGFR-like receptor in nonvertebrates appears to be the ancestor of the 7 Ig- and 5 Ig-RTK families because most nonvertebrates have only a single 7 Ig-RTK gene. In mammals, VEGFRs are deeply involved in pathological angiogenesis, including cancer and inflammation. Thus, an efficient inhibitor targeting VEGFRs could be useful in suppressing various diseases.

Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are key drivers of blood and lymph vessel formation in development, but also in several pathological processes. VEGF-C signaling through VEGFR-3 promotes lymphangiogenesis, which is a clinically relevant target for treating lymphatic insufficiency and for blocking tumor angiogenesis and metastasis. The extracellular domain of VEGFRs consists of seven Ig homology domains; domains 1-3 (D1-3) are responsible for ligand binding, and the membrane-proximal domains 4-7 (D4-7) are involved in structural rearrangements essential for receptor dimerization and activation. Here we analyzed the crystal structures of VEGF-C in complex with VEGFR-3 domains D1-2 and of the VEGFR-3 D4-5 homodimer. The structures revealed a conserved ligand-binding interface in D2 and a unique mechanism for VEGFR dimerization and activation, with homotypic interactions in D5. Mutation of the conserved residues mediating the D5 interaction (Thr446 and Lys516) and the D7 interaction (Arg737) compromised VEGF-C induced VEGFR-3 activation. A thermodynamic analysis of VEGFR-3 deletion mutants showed that D3, D4-5, and D6-7 all contribute to ligand binding. A structural model of the VEGF-C/VEGFR-3 D1-7 complex derived from small-angle X-ray scattering data is consistent with the homotypic interactions in D5 and D7. Taken together, our data show that ligand-dependent homotypic interactions in D5 and D7 are essential for VEGFR activation, opening promising possibilities for the design of VEGFR-specific drugs.

VEGF-D is an angiogenic and lymphangiogenic glycoprotein that can be proteolytically processed generating various forms differing in subunit composition due to the presence or absence of N- and C-terminal propeptides. These propeptides flank the central VEGF homology domain, that contains the binding sites for VEGF receptors (VEGFRs), but their biological functions were unclear. Characterization of propeptide function will be important to clarify which forms of VEGF-D are biologically active and therefore clinically relevant. Here we use VEGF-D mutants deficient in either propeptide, and in the capacity to process the remaining propeptide, to monitor the functions of these domains. We report for the first time that VEGF-D binds heparin, and that the C-terminal propeptide significantly enhances this interaction (removal of this propeptide from full-length VEGF-D completely prevents heparin binding). We also show that removal of either the N- or C-terminal propeptide is required for VEGF-D to drive formation of VEGFR-2/VEGFR-3 heterodimers which have recently been shown to positively regulate angiogenic sprouting. The mature form of VEGF-D, lacking both propeptides, can also promote formation of these receptor heterodimers. In a mouse tumor model, removal of only the C-terminal propeptide from full-length VEGF-D was sufficient to enhance angiogenesis and tumor growth. In contrast, removal of both propeptides is required for high rates of lymph node metastasis. The findings reported here show that the propeptides profoundly influence molecular interactions of VEGF-D with VEGF receptors, co-receptors, and heparin, and its effects on tumor biology.

Feline McDonough Sarcoma (FMS)-like tyrosine kinase 4 (FLT4) is a marker for lymphatic vessels and some high endothelial venules in human adult tissues. We generated a transgenic medaka fish in which the lymphatic vessels and some blood vessels are visible in vivo by transferring the promoter of medaka flt4 driving the expression of enhanced green fluorescent protein (EGFP) using a see-through medaka line. To do this, we identified and cloned medaka flt4 and generated a construct in which the promoter was the 4-kb region upstream of the translation initiation site. The fluorescent signal of EGFP could be observed with little background, and the expression pattern correlated well with that of flt4 determined by whole-mount RNA in situ hybridization. Because a see-through medaka line is transparent until adult, the model is useful for visualizing the lymphatic vessels not only in embryo and fry but also in adult. This model will be a useful tool for analyzing lymphatic development., (Copyright © 2012 Wiley Periodicals, Inc.)

The presence of lymphatic vessels in dental pulp has recently been controversial, and no conclusion has been reached. In this study, we investigated the control of lymphangiogenesis with dental pulp development in the mouse mandibular molar using VEGF-C, VEGF-D, and VEGFR-3 as indices of lymphatic vessel-controlling factors. In addition, to distinguish blood and lymphatic vascular epithelial cells, we performed immunohistochemical analysis using von Willebrand factor (vWF) and statistical analysis. In dental papilla in the bell-stage non-calcified period, mesenchymal cells positive for VEGF-C, VEGF-D, and VEGFR-3 increased and lumen-forming endothelial cells were noted, but vWF was negative, suggesting that these were actively forming lymphatic vessels. Positive undifferentiated mesenchymal cells, an increase in endothelial cells in dental pulp, and lumen expansion were noted early after birth. Positivity was also detected in the odontoblast layer and sheath of Hertwig after birth, suggesting that these factors also play important roles in odontoblast differentiation and maturation and periodontal ligament and tooth root formation. We embryologically clarified lymphatic vessel formation in dental pulp and a process of lymphatic vessel formation from blood vessels, suggesting involvement of the surrounding tissue, odontoblasts, and sheath of Hertwig in vessel formation., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

VEGFs activate 3 receptor tyrosine kinases, VEGFR-1, VEGFR-2, and VEGFR-3, promoting angiogenic and lymphangiogenic signaling. The extracellular receptor domain (ECD) consists of 7 Ig-homology domains; domains 2 and 3 (D23) represent the ligand-binding domain, whereas the function of D4-7 is unclear. Ligand binding promotes receptor dimerization and instigates transmembrane signaling and receptor kinase activation. In the present study, isothermal titration calorimetry showed that the Gibbs free energy of VEGF-A, VEGF-C, or VEGF-E binding to D23 or the full-length ECD of VEGFR-2 is dominated by favorable entropic contribution with enthalpic penalty. The free energy of VEGF binding to the ECD is 1.0-1.7 kcal/mol less favorable than for binding to D23. A model of the VEGF-E/VEGFR-2 ECD complex derived from small-angle scattering data provided evidence for homotypic interactions in D4-7. We also solved the crystal structures of complexes between VEGF-A or VEGF-E with D23, which revealed comparable binding surfaces and similar interactions between the ligands and the receptor, but showed variation in D23 twist angles. The energetically unfavorable homotypic interactions in D4-7 may be required for re-orientation of receptor monomers, and this mechanism might prevent ligand-independent activation of VEGFR-2 to evade the deleterious consequences for blood and lymph vessel homeostasis arising from inappropriate receptor activation.

Antibodies that block vascular endothelial growth factor (VEGF) have become an integral part of antiangiogenic tumor therapy, and antibodies targeting other VEGFs and receptors (VEGFRs) are in clinical trials. Typically receptor-blocking antibodies are targeted to the VEGFR ligand-binding site. Here we describe a monoclonal antibody that inhibits VEGFR-3 homodimer and VEGFR-3/VEGFR-2 heterodimer formation, signal transduction, as well as ligand-induced migration and sprouting of microvascular endothelial cells. Importantly, we show that combined use of antibodies blocking ligand binding and receptor dimerization improves VEGFR inhibition and results in stronger inhibition of endothelial sprouting and vascular network formation in vivo. These results suggest that receptor dimerization inhibitors could be used to enhance antiangiogenic activity of antibodies blocking ligand binding in tumor therapy., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Vascular endothelial growth factors (VEGFs) regulate blood and lymph vessel formation through activation of three receptor tyrosine kinases, VEGFR-1, -2, and -3. The extracellular domain of VEGF receptors consists of seven immunoglobulin homology domains, which, upon ligand binding, promote receptor dimerization. Dimerization initiates transmembrane signaling, which activates the intracellular tyrosine kinase domain of the receptor. VEGF-C stimulates lymphangiogenesis and contributes to pathological angiogenesis via VEGFR-3. However, proteolytically processed VEGF-C also stimulates VEGFR-2, the predominant transducer of signals required for physiological and pathological angiogenesis. Here we present the crystal structure of VEGF-C bound to the VEGFR-2 high-affinity-binding site, which consists of immunoglobulin homology domains D2 and D3. This structure reveals a symmetrical 22 complex, in which left-handed twisted receptor domains wrap around the 2-fold axis of VEGF-C. In the VEGFs, receptor specificity is determined by an N-terminal alpha helix and three peptide loops. Our structure shows that two of these loops in VEGF-C bind to VEGFR-2 subdomains D2 and D3, while one interacts primarily with D3. Additionally, the N-terminal helix of VEGF-C interacts with D2, and the groove separating the two VEGF-C monomers binds to the D2/D3 linker. VEGF-C, unlike VEGF-A, does not bind VEGFR-1. We therefore created VEGFR-1/VEGFR-2 chimeric proteins to further study receptor specificity. This biochemical analysis, together with our structural data, defined VEGFR-2 residues critical for the binding of VEGF-A and VEGF-C. Our results provide significant insights into the structural features that determine the high affinity and specificity of VEGF/VEGFR interactions.

The development of arteries, veins and lymphatics from pre-existing vessels are intimately linked processes controlled by a number of well-studied reiteratively acting signalling pathways. To delineate the mechanisms governing vessel formation in vivo, we performed a forward genetic screen in zebrafish and isolated the mutant expando. Molecular characterisation revealed a loss-of-function mutation in the highly conserved kinase insert region of flt4. Consistent with previous reports, flt4 mutants were deficient in lymphatic vascular development. Recent studies have demonstrated a role for Flt4 in blood vessels and showed that Dll4 limits angiogenic potential by limiting Flt4 function in developing blood vessels. We found that arterial angiogenesis proceeded normally, yet the dll4 loss-of-function arterial hyperbranching phenotype was rescued, in flt4 signalling mutants. Furthermore, we found that the Flt4 ligand Vegfc drives arterial hyperbranching in the absence of dll4. Upon knockdown of dll4, intersegmental arteries were sensitised to increased vegfc levels and the overexpression of dll4 inhibited Vegfc/Flt4-dependent angiogenesis events. Taken together, these data demonstrate that dll4 functions to suppress the ability of developing intersegmental arteries to respond to Vegfc-driven Flt4 signalling in zebrafish. We propose that this mechanism contributes to the differential response of developing arteries and veins to a constant source of Vegfc present in the embryo during angiogenesis.

The vascular endothelial growth factors are key mediators of angiogenesis and are also related to several physiological processes such as monocyte chemotaxis, dendritic cell development, hematopoietic stem cell survival, and many others. PlGF, VEGF, VEGFB, VEGFC and VEGFD were identified as members of the vascular endothelial growth factor family. They act by differential activation of three receptors: Flt-1, KDR and Flt-4. PlGF and VEGFB only activate Flt-1. VEGF activates both Flt-1 and KDR. VEGFC and VEGFD activate KDR and Flt-4. The available three dimensional structures of VEGF and PlGF, in complex with the domain-2 of Flt-1, show that both proteins bind in a very similar way to Flt-1 receptor. Here we construct the three dimensional model of the domain-2 of KDR receptor using the same domain of Flt-1 as template. We also construct the model complexes VEGF/KDR, VEGFB/Flt-1, VEGFB/KDR and PlGF/KDR. Molecular dynamics simulations with explicit solvent are carried out on eleven molecular systems: unbound VEGF, VEGF/Flt-1(D2), VEGF/KDR(D2), unbound PlGF, PlGF/Flt-1(D2), PlGF/KDR(D2), unbound VEGFB, VEGFB/Flt-1(D2), VEGFB/KDR(D2), unbound Flt-1(D2) and unbound KDR(D2). We analyze protein-protein interactions, shape complementarity, charge complementarity and hydrogen bonds. As a coarse estimation of the desolvation penalties, we assume a correlation to the number of hydrogen bonds with solvent molecules that are lost upon complex formation. The results herein are consistent with the experimental selectivity profile (VEGF being able to activate both Flt-1 and KDR receptors while VEGFB and PlGF being only able to activate Flt-1), and provide a collection of evidences sustaining the complementarity of polar interactions as the main responsible for protein recognition and selectivity.

Neostatin-7, with an anti-angiogenic potential, is generated from the proteolytic action of matrix metalloproteinase-7 on collagen XVIII. We previously reported that neostatin-7 inhibited angiogenesis in vitro and in vivo. Here we demonstrate that neostatin-7/collagen XVIII may possess anti-lymphangiogenic activities by: (1) corneal micropellet implantation of neostatin-7 reduced bFGF-induced corneal lymphangiogenesis; (2) neostatin-7 bound to VEGF receptor-3 in vitro; and (3) enhanced corneal lymphangiogenesis and VEGF-C expression in collagen XVIII knockout mice in a corneal wounding model. Understanding the mechanism of neostatin-7/collagen XVIII on corneal lymphangiogenesis may provide therapeutic interventions to treat lymphangiogenesis-related disorders, such as lymphedema, transplantation rejection and cancers.

A novel mutation of vascular endothelial growth factor receptor gene (VEGFR-3), was identified in a four-generation Chinese family with hereditary lymphedema type I (HL-I). Genetic linkage analysis was performed on the known genetic locus for HL-I with a panel of polymorphic markers, and then mutations were screened out by direct sequencing. By genotyping, the family showed the linkage to HL-I locus on 5q35.3. Mutation screening analysis of the exons encoding the intracellular kinase domains of VEGFR-3, revealed a novel missense mutation D1055V. This mutation cosegregated with the disease phenotype in the family and was not found in 100 normal controls. This finding has expanded the spectrum of the VEGFR-3 gene mutations causing HL-I, and will be useful for further genetic consultation and genetic diagnosis.

Milroy disease, also known as primary congenital lymphedema, is a hereditary form of lymphedema with autosomal dominant inheritance. Individuals with Milroy disease are typically characterized by congenital onset of lymphedema of the lower limbs due to hypoplasia of the lymphatic vessels. The genetic basis of most cases of Milroy disease has not been established, although mutations in the vascular endothelial growth factor receptor VEGFR3 (FLT-4) are responsible for some cases with 17 mutations described to date. In this report, we describe a novel VEGFR3 mutation in exon 22 in a four-generation family in which congenital lymphedema segregates in an autosomal dominant manner. In addition to lymphedema, affected family members had other clinical manifestations associated with Milroy disease including hydrocele, ski jump toenails, large caliber veins, and subcutaneous thickening. We screened VEGFR3 for mutations which revealed a novel 3059A>T transversion in exon 22 resulting in Q1020L missense mutation in the second tyrosine kinase domain of VEGFR3. This mutant allele segregated with lymphedema among affected individuals with incomplete penetrance. This is the first report of an exon 22 mutation in Milroy disease., (Copyright (c) 2007 Wiley-Liss, Inc.)

We report on selectivity profiling of 1 in a panel of 20 protein kinases and molecular modeling indicating 1 to be highly active and selective for VEGF-R2/3. Sequence alignment analysis and detailed insights into the ATP binding pockets of targeted protein kinases from the panel result in a unique structural architecture of VEGF-R2 mainly caused by the hydrophobic pocket I, determining the molecular basis for activity and selectivity of 1.

Transparency of the cornea, the window of the eye, is a prerequisite for vision. Angiogenesis into the normally avascular cornea is incompatible with good vision and, therefore, the cornea is one of the few tissues in the human body where avascularity is actively maintained. Here, we provide evidence for a critical mechanism contributing to corneal avascularity. VEGF receptor 3, normally present on lymphatic and proliferating blood vascular endothelium, is strongly constitutively expressed by corneal epithelium and is mechanistically responsible for suppressing inflammatory corneal angiogenesis.

Vascular endothelial growth factors (VEGF) and their receptors (VEGFR) have been implicated to play important roles in tumor-associated angiogenesis and lymphangiogenesis, and hence in tumor growth and metastasis. We previously produced a number of fully human antibodies directed against VEGF receptor 2 (VEGFR2) and VEGF receptor 3 (VEGFR3) and showed that these antibodies are capable of inhibiting growth factor (VEGF and VEGF-C)-induced receptor activation, migration, and proliferation of human endothelial cells. In this report, we constructed and produced a bispecific antibody, a diabody, using the variable domain genes of two neutralizing antibodies, IMC-1121 to VEGFR2 and hF4-3C5 to VEGFR3. The diabody binds to both VEGFR2 and VEGFR3 in a dose-dependent manner, and blocks interaction between VEGF/VEGFR2, VEGF-C/VEGFR2, and VEGF-C/VEGFR3. In cell-based assays, the diabody neutralized both VEGF and VEGF-C-stimulated activation of VEGFR2, VEGFR3, and p44/p42 mitogen-activated protein kinase in endothelial cells. Furthermore, the diabody was able to inhibit both VEGF and VEGF-C-induced migration of endothelial cells. Taken together, our results suggest that a dual blockade of both VEGFR2 and VEGFR3 simultaneously may represent a more potent approach to effective cancer therapy.

VEGFR-3 is essential for vascular development and maintenance of lymphatic vessel's integrity. Little is known about its cooperative effect with other receptors of the same family. Contrary to VEGFR-2, stimulation of VEGFR-3 by VEGF-C and -D failed to enhance its phosphorylation either in HEK293T or in PAE cells. These ligands were unable to induce angiogenesis of PAEC expressing VEGFR-3 alone. In the presence of VEGFR-2, VEGF-C and -D induced heterodimerization of VEGFR-3 with VEGFR-2. This heterodimerization was associated with enhanced VEGFR-3 phosphorylation and subsequent cellular responses as evidenced by the formation of capillary-like structures in PAE cells and proliferation of primary human endothelial cells expressing both receptors. Taken together, these results show for the first time that VEGFR-3 needs to be associated to VEGFR-2 to induce ligand-dependent cellular responses.

The life sciences are molecular and the harnessing of information gleaned from genomics and proteomics will require interdisciplinary research integrating chemistry and biology. This approach is illustrated by the synthesis and biological evaluation of lipidated peptides and proteins and the delineation of a concept arguing for natural product guided combinatorial chemistry.