%0 Journal Article %J Circ Res %D 2015 %T Functional Dissection of the CCBE1 Protein: A Crucial Requirement for the Collagen Repeat Domain. %A Roukens, M Guy %A Peterson-Maduro, Josi %A Padberg, Yvonne %A Jeltsch, Michael %A Leppänen, Veli-Matti %A Bos, Frank L %A Alitalo, Kari %A Schulte-Merker, Stefan %A Schulte, Dörte %K Animals %K Binding Sites %K Calcium-Binding Proteins %K Collagen %K Craniofacial Abnormalities %K Endothelial Cells %K Epidermal Growth Factor %K Gene Expression Regulation, Developmental %K Gene Knock-In Techniques %K Genital Diseases, Male %K Genotype %K Gestational Age %K HEK293 Cells %K Humans %K Lymphangiectasis, Intestinal %K Lymphatic Vessels %K lymphedema %K Mice %K Mice, Transgenic %K Mutation %K Phenotype %K Protein Binding %K Protein Interaction Domains and Motifs %K Signal Transduction %K Transfection %K Tumor Suppressor Proteins %K Vascular Endothelial Growth Factor C %K Zebrafish %K Zebrafish Proteins %X

RATIONALE: Collagen- and calcium-binding EGF domain-containing protein 1 (CCBE1) is essential for lymphangiogenesis in vertebrates and has been associated with Hennekam syndrome. Recently, CCBE1 has emerged as a crucial regulator of vascular endothelial growth factor-C (VEGFC) signaling.

OBJECTIVE: CCBE1 is a secreted protein characterized by 2 EGF domains and 2 collagen repeats. The functional role of the different CCBE1 protein domains is completely unknown. Here, we analyzed the functional role of the different CCBE1 domains in vivo and in vitro.

METHODS AND RESULTS: We analyzed the functionality of several CCBE1 deletion mutants by generating knock-in mice expressing these mutants, by analyzing their ability to enhance Vegfc signaling in vivo in zebrafish, and by testing their ability to induce VEGFC processing in vitro. We found that deleting the collagen domains of CCBE1 has a much stronger effect on CCBE1 activity than deleting the EGF domains. First, although CCBE1ΔCollagen mice fully phenocopy CCBE1 knock-out mice, CCBE1ΔEGF knock-in embryos still form rudimentary lymphatics. Second, Ccbe1ΔEGF, but not Ccbe1ΔCollagen, could partially substitute for Ccbe1 to enhance Vegfc signaling in zebrafish. Third, CCBE1ΔEGF, similarly to CCBE1, but not CCBE1ΔCollagen could activate VEGFC processing in vitro. Furthermore, a Hennekam syndrome mutation within the collagen domain has a stronger effect than a Hennekam syndrome mutation within the EGF domain.

CONCLUSIONS: We propose that the collagen domains of CCBE1 are crucial for the activation of VEGFC in vitro and in vivo. The EGF domains of CCBE1 are dispensable for regulation of VEGFC processing in vitro, however, they are necessary for full lymphangiogenic activity of CCBE1 in vivo.

%B Circ Res %V 116 %P 1660-1669 %8 2015 May 8 %G eng %U http://circres.ahajournals.org/content/116/10/1660.long %N 10 %R 10.1161/CIRCRESAHA.116.304949 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2013 %T Structural and mechanistic insights into VEGF receptor 3 ligand binding and activation %A Leppänen, Veli-Matti %A Tvorogov, Denis %A Kisko, Kaisa %A Prota, Andrea E %A Jeltsch, Michael %A Anisimov, Andrey %A Markovic-Mueller, Sandra %A Stuttfeld, Edward %A Goldie, Kenneth N %A Ballmer-Hofer, Kurt %A Alitalo, Kari %K Amino Acid Sequence %K Binding Sites %K Binding, Competitive %K Crystallography, X-Ray %K Electrophoresis, Polyacrylamide Gel %K Humans %K Ligands %K Microscopy, Electron %K Models, Molecular %K Molecular Sequence Data %K Multiprotein Complexes %K Mutation %K Protein Binding %K Protein Multimerization %K Protein Structure, Tertiary %K Scattering, Small Angle %K Sequence Homology, Amino Acid %K Thermodynamics %K Vascular Endothelial Growth Factor C %K Vascular Endothelial Growth Factor Receptor-3 %K X-Ray Diffraction %X 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. %B Proceedings of the National Academy of Sciences of the United States of America %V 110 %P 12960 - 12965 %8 08/2013 %@ 1091-6490 %G eng %U http://www.pnas.org/content/110/32/12960.long %N 32 %! Proc. Natl. Acad. Sci. U.S.A. %R 10.1073/pnas.1301415110 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2010 %T Structural determinants of growth factor binding and specificity by VEGF receptor 2 %A Leppänen, Veli-Matti %A Prota, Andrea E %A Jeltsch, Michael %A Anisimov, Andrey %A Kalkkinen, Nisse %A Strandin, Tomas %A Lankinen, Hilkka %A Goldman, Adrian %A Ballmer-Hofer, Kurt %A Alitalo, Kari %X 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. %B Proceedings of the National Academy of Sciences of the United States of America %V 107 %P 2425 - 30 %8 02/2010 %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/20145116 %N 6 %0 Journal Article %J PLoS ONE %D 2010 %T Suppressive effects of vascular endothelial growth factor-B on tumor growth in a mouse model of pancreatic neuroendocrine tumorigenesis %A Albrecht, Imke %A Kopfstein, Lucie %A Strittmatter, Karin %A Schomber, Tibor %A Falkevall, Annelie %A Hagberg, Carolina E %A Lorentz, Pascal %A Jeltsch, Michael %A Alitalo, Kari %A Eriksson, Ulf %A Christofori, Gerhard %A Pietras, Kristian %X BACKGROUND: The family of vascular endothelial growth factors (VEGF) contains key regulators of blood and lymph vessel development, including VEGF-A, -B, -C, -D, and placental growth factor. The role of VEGF-B during physiological or pathological angiogenesis has not yet been conclusively delineated. Herein, we investigate the function of VEGF-B by the generation of mouse models of cancer with transgenic expression of VEGF-B or homozygous deletion of Vegfb. METHODOLOGY/PRINCIPAL FINDINGS: Ectopic expression of VEGF-B in the insulin-producing β-cells of the pancreas did not alter the abundance or architecture of the islets of Langerhans. The vasculature from transgenic mice exhibited a dilated morphology, but was of similar density as that of wildtype mice. Unexpectedly, we found that transgenic expression of VEGF-B in the RIP1-Tag2 mouse model of pancreatic neuroendocrine tumorigenesis retarded tumor growth. Conversely, RIP1-Tag2 mice deficient for Vegfb presented with larger tumors. No differences in vascular density, perfusion or immune cell infiltration upon altered Vegfb gene dosage were noted. However, VEGF-B acted to increase blood vessel diameter both in normal pancreatic islets and in RIP1-Tag2 tumors. CONCLUSIONS/SIGNIFICANCE: Taken together, our results illustrate the differences in biological function between members of the VEGF family, and highlight the necessity of in-depth functional studies of VEGF-B to fully understand the effects of VEGFR-1 inhibitors currently used in the clinic. %B PLoS ONE %V 5 %P e14109 %8 2010// %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/21124841 %N 11 %! PLoS ONE %0 Journal Article %J Circ Res %D 2008 %T Overexpression of vascular endothelial growth factor-B in mouse heart alters cardiac lipid metabolism and induces myocardial hypertrophy %A Karpanen, Terhi %A Bry, Maija %A Ollila, Hanna M %A Seppänen-Laakso, Tuulikki %A Liimatta, Erkki %A Leskinen, Hanna %A Kivelä, Riikka %A Helkamaa, Teemu %A Merentie, Mari %A Jeltsch, Michael %A Paavonen, Karri %A Andersson, Leif C %A Mervaala, Eero %A Hassinen, Ilmo E %A Ylä-Herttuala, Seppo %A Oresic, Matej %A Alitalo, Kari %X Vascular endothelial growth factor (VEGF)-B is poorly angiogenic but prominently expressed in metabolically highly active tissues, including the heart. We produced mice expressing a cardiac-specific VEGF-B transgene via the alpha-myosin heavy chain promoter. Surprisingly, the hearts of the VEGF-B transgenic mice showed concentric cardiac hypertrophy without significant changes in heart function. The cardiac hypertrophy was attributable to an increased size of the cardiomyocytes. Blood capillary size was increased, whereas the number of blood vessels per cell nucleus remained unchanged. Despite the cardiac hypertrophy, the transgenic mice had lower heart rate and blood pressure than their littermates, and they responded similarly to angiotensin II-induced hypertension, confirming that the hypertrophy does not compromise heart function. Interestingly, the isolated transgenic hearts had less cardiomyocyte damage after ischemia. Significantly increased ceramide and decreased triglyceride levels were found in the transgenic hearts. This was associated with structural changes and eventual lysis of mitochondria, resulting in accumulation of intracellular vacuoles in cardiomyocytes and increased death of the transgenic mice, apparently because of mitochondrial lipotoxicity in the heart. These results suggest that VEGF-B regulates lipid metabolism, an unexpected function for an angiogenic growth factor. %B Circ Res %V 103 %P 1018 - 26 %8 2008/Oct/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/18757827 %N 9 %! Circulation Research %0 Journal Article %J Arterioscler Thromb Vasc Biol %D 2008 %T Reevaluation of the role of VEGF-B suggests a restricted role in the revascularization of the ischemic myocardium %A Li, Xuri %A Tjwa, Marc %A Van Hove, Inge %A Enholm, Berndt %A Neven, Elke %A Paavonen, Karri %A Jeltsch, Michael %A Juan, Toni Diez %A Sievers, Richard E %A Chorianopoulos, Emmanuel %A Wada, Hiromichi %A Vanwildemeersch, Maarten %A Noel, Agnes %A Foidart, Jean-Michel %A Springer, Matthew L %A von Degenfeld, Georges %A Dewerchin, Mieke %A Blau, Helen M %A Alitalo, Kari %A Eriksson, Ulf %A Carmeliet, Peter %A Moons, Lieve %X OBJECTIVE: The endogenous role of the VEGF family member vascular endothelial growth factor-B (VEGF-B) in pathological angiogenesis remains unclear. METHODS AND RESULTS: We studied the role of VEGF-B in various models of pathological angiogenesis using mice lacking VEGF-B (VEGF-B(-/-)) or overexpressing VEGF-B(167). After occlusion of the left coronary artery, VEGF-B deficiency impaired vessel growth in the ischemic myocardium whereas, in wild-type mice, VEGF-B(167) overexpression enhanced revascularization of the infarct and ischemic border zone. By contrast, VEGF-B deficiency did not affect vessel growth in the wounded skin, hypoxic lung, ischemic retina, or ischemic limb. Moreover, VEGF-B(167) overexpression failed to enhance vascular growth in the skin or ischemic limb. CONCLUSIONS: VEGF-B appears to have a relatively restricted angiogenic activity in the ischemic heart. These insights might offer novel therapeutic opportunities. %B Arterioscler Thromb Vasc Biol %V 28 %P 1614 - 20 %8 2008/Sep/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/18511699 %N 9 %! Arteriosclerosis, Thrombosis, and Vascular Biology %0 Journal Article %J Circ Res %D 2007 %T Distinct architecture of lymphatic vessels induced by chimeric vascular endothelial growth factor-C/vascular endothelial growth factor heparin-binding domain fusion proteins %A Tammela, Tuomas %A He, Yulong %A Lyytikkä, Johannes %A Jeltsch, Michael %A Markkanen, Johanna %A Pajusola, Katri %A Ylä-Herttuala, Seppo %A Alitalo, Kari %X Vascular endothelial growth factor (VEGF)-C and VEGF-D are composed of the receptor-binding VEGF homology domain and a carboxy-terminal silk homology domain that requires proteolytic cleavage for growth factor activation. Here, we explored whether the C-terminal heparin-binding domain of the VEGF(165) or VEGF(189) isoform also containing neuropilin-binding sequences could substitute for the silk homology domain of VEGF-C. Such VEGF-C/VEGF-heparin-binding domain chimeras were produced and shown to activate VEGF-C receptors, and, when expressed in tissues via adenovirus or adeno-associated virus vectors, stimulated lymphangiogenesis in vivo. However, both chimeras induced a distinctly different pattern of lymphatic vessels when compared with VEGF-C. Whereas VEGF-C-induced vessels were initially a dense network of small diameter vessels, the lymphatic vessels induced by the chimeric growth factors tended to form directly along tissue borders, along basement membranes that are rich in heparan sulfate. For example, in skeletal muscle, the chimeras induced formation of lumenized lymphatic vessels more efficiently than wild-type VEGF-C. We conclude that the matrix-binding domain of VEGF can target VEGF-C activity to heparin-rich basement membrane structures. These properties may prove useful for tissue engineering and attempts to regenerate lymphatic vessels in lymphedema patients. %B Circ Res %V 100 %P 1468 - 75 %8 2007/May/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/17478733 %N 10 %! Circulation Research %0 Journal Article %J J Clin Invest %D 2005 %T Pathogenesis of persistent lymphatic vessel hyperplasia in chronic airway inflammation %A Baluk, Peter %A Tammela, Tuomas %A Ator, Erin %A Lyubynska, Natalya %A Achen, Marc G %A Hicklin, Daniel J %A Jeltsch, Michael %A Petrova, Tatiana V %A Pytowski, Bronislaw %A Stacker, Steven A %A Ylä-Herttuala, Seppo %A Jackson, David G %A Alitalo, Kari %A McDonald, Donald M %X Edema occurs in asthma and other inflammatory diseases when the rate of plasma leakage from blood vessels exceeds the drainage through lymphatic vessels and other routes. It is unclear to what extent lymphatic vessels grow to compensate for increased leakage during inflammation and what drives the lymphangiogenesis that does occur. We addressed these issues in mouse models of (a) chronic respiratory tract infection with Mycoplasma pulmonis and (b) adenoviral transduction of airway epithelium with VEGF family growth factors. Blood vessel remodeling and lymphangiogenesis were both robust in infected airways. Inhibition of VEGFR-3 signaling completely prevented the growth of lymphatic vessels but not blood vessels. Lack of lymphatic growth exaggerated mucosal edema and reduced the hypertrophy of draining lymph nodes. Airway dendritic cells, macrophages, neutrophils, and epithelial cells expressed the VEGFR-3 ligands VEGF-C or VEGF-D. Adenoviral delivery of either VEGF-C or VEGF-D evoked lymphangiogenesis without angiogenesis, whereas adenoviral VEGF had the opposite effect. After antibiotic treatment of the infection, inflammation and remodeling of blood vessels quickly subsided, but lymphatic vessels persisted. Together, these findings suggest that when lymphangiogenesis is impaired, airway inflammation may lead to bronchial lymphedema and exaggerated airflow obstruction. Correction of defective lymphangiogenesis may benefit the treatment of asthma and other inflammatory airway diseases. %B J Clin Invest %V 115 %P 247 - 57 %8 2005/Feb/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/15668734 %N 2 %! The Journal of Clinical Investigation %0 Journal Article %J Cancer Res %D 2005 %T Vascular endothelial cell growth factor receptor 3-mediated activation of lymphatic endothelium is crucial for tumor cell entry and spread via lymphatic vessels %A He, Yulong %A Rajantie, Iiro %A Pajusola, Katri %A Jeltsch, Michael %A Holopainen, Tanja %A Yla-Herttuala, Seppo %A Harding, Thomas %A Jooss, Karin %A Takahashi, Takashi %A Alitalo, Kari %X Lymphangiogenic growth factors vascular endothelial growth factor (VEGF)-C and VEGF-D have been shown to promote lymphatic metastasis by inducing tumor-associated lymphangiogenesis. In this study, we have investigated how tumor cells gain access into lymphatic vessels and at what stage tumor cells initiate metastasis. We show that VEGF-C produced by tumor cells induced extensive lymphatic sprouting towards the tumor cells as well as dilation of the draining lymphatic vessels, suggesting an active role of lymphatic endothelial cells in lymphatic metastasis. A significant increase in lymphatic vessel growth occurred between 2 and 3 weeks after tumor xenotransplantation, and lymph node metastasis occurred at the same stage. These processes were blocked dose-dependently by inhibition of VEGF receptor 3 (VEGFR-3) signaling by systemic delivery of a soluble VEGFR-3-immunoglobulin (Ig) fusion protein via adenoviral or adeno-associated viral vectors. However, VEGFR-3-Ig did not suppress lymph node metastasis when the treatment was started at a later stage after the tumor cells had already spread out, suggesting that tumor cell entry into lymphatic vessels is a key step during tumor dissemination via the lymphatics. Whereas lymphangiogenesis and lymph node metastasis were significantly inhibited by VEGFR-3-Ig, some tumor cells were still detected in the lymph nodes in some of the treated mice. This indicates that complete blockade of lymphatic metastasis may require the targeting of both tumor lymphangiogenesis and tumor cell invasion. %B Cancer Res %V 65 %P 4739 - 46 %8 2005/Jun/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/15930292 %N 11 %! Cancer Research %0 Journal Article %J Nat Immunol %D 2004 %T Vascular endothelial growth factor C is required for sprouting of the first lymphatic vessels from embryonic veins %A Karkkainen, Marika J %A Haiko, Paula %A Sainio, Kirsi %A Partanen, Juha %A Taipale, Jussi %A Petrova, Tatiana V %A Jeltsch, Michael %A Jackson, David G %A Talikka, Marja %A Rauvala, Heikki %A Betsholtz, Christer %A Alitalo, Kari %X Lymphatic vessels are essential for immune surveillance, tissue fluid homeostasis and fat absorption. Defects in lymphatic vessel formation or function cause lymphedema. Here we show that the vascular endothelial growth factor C (VEGF-C) is required for the initial steps in lymphatic development. In Vegfc-/- mice, endothelial cells commit to the lymphatic lineage but do not sprout to form lymph vessels. Sprouting was rescued by VEGF-C and VEGF-D but not by VEGF, indicating VEGF receptor 3 specificity. The lack of lymphatic vessels resulted in prenatal death due to fluid accumulation in tissues, and Vegfc+/- mice developed cutaneous lymphatic hypoplasia and lymphedema. Our results indicate that VEGF-C is the paracrine factor essential for lymphangiogenesis, and show that both Vegfc alleles are required for normal lymphatic development. %B Nat Immunol %V 5 %P 74 - 80 %8 2004/Jan/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/14634646 %N 1 %! Nature Immunology %0 Journal Article %J FASEB J %D 2003 %T Intrinsic versus microenvironmental regulation of lymphatic endothelial cell phenotype and function %A Veikkola, Tanja %A Lohela, Marja %A Ikenberg, Kristian %A Mäkinen, Taija %A Korff, Thomas %A Saaristo, Anne %A Petrova, Tatania %A Jeltsch, Michael %A Augustin, Hellmut G %A Alitalo, Kari %X Vascular endothelial cells are characterized by a high degree of functional and phenotypic plasticity, which is controlled both by their pericellular microenvironment and their intracellular gene expression programs. To gain further insight into the mechanisms regulating the endothelial cell phenotype, we have compared the responses of lymphatic endothelial cells (LECs) and blood vascular endothelial cells (BECs) to vascular endothelial growth factors (VEGFs). VEGFR-3-specific signals are sufficient for LEC but not BEC proliferation, as shown by the ability of the specific ligand VEGF-C156S to stimulate cell cycle entry only in LECs. On the other hand, we found that VEGFR-3 stimulation did not induce LEC cell shape changes typical of VEGFR-2-stimulated LECs, indicating receptor-specific differences in the cytoskeletal responses. Genes induced via VEGFR-2 also differed between BECs and LECs: angiopoietin-2 (Ang-2) was induced via VEGFR-2 in BECs and LECs, but the smooth muscle cell (SMC) chemoattractant BMP-2 was induced only in BECs. Both BECs and LECs were able to promote SMC chemotaxis, but contact with SMCs led to down-regulation of VEGFR-3 expression in BECs in a 3-dimensional coculture system. This was consistent with the finding that VEGFR-3 is down-regulated in vivo at sites of endothelial cell-pericyte/smooth muscle cell contacts. Collectively, these data show intrinsic cell-specific differences of BEC and LEC responses to VEGFs and identify a pericellular regulatory mechanism for VEGFR-3 down-regulation in endothelial cells. %B FASEB J %V 17 %P 2006 - 13 %8 2003/Nov/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/14597670 %N 14 %! The FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology %0 Journal Article %J FASEB J %D 2002 %T Adenoviral VEGF-C overexpression induces blood vessel enlargement, tortuosity, and leakiness but no sprouting angiogenesis in the skin or mucous membranes %A Saaristo, Anne %A Veikkola, Tanja %A Enholm, Berndt %A Hytönen, Maija %A Arola, Johanna %A Pajusola, Katri %A Turunen, Païvi %A Jeltsch, Michael %A Karkkainen, Marika J %A Kerjaschki, Dontscho %A Bueler, Hansruedi %A Ylä-Herttuala, Seppo %A Alitalo, Kari %X Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are important regulators of blood and lymphatic vessel growth and vascular permeability. The VEGF-C/VEGFR-3 signaling pathway is crucial for lymphangiogenesis, and heterozygous inactivating missense mutations of the VEGFR-3 gene are associated with hereditary lymphedema. However, VEGF-C can have potent effects on blood vessels because its receptor VEGFR-3 is expressed in certain blood vessels and because the fully processed form of VEGF-C also binds to the VEGFR-2 of blood vessels. To characterize the in vivo effects of VEGF-C on blood and lymphatic vessels, we have overexpressed VEGF-C via adenovirus- and adeno-associated virus-mediated transfection in the skin and respiratory tract of athymic nude mice. This resulted in dose-dependent enlargement and tortuosity of veins, which, along with the collecting lymphatic vessels were found to express VEGFR-2. Expression of angiopoietin 1 blocked the increased leakiness of the blood vessels induced by VEGF-C whereas vessel enlargement and lymphangiogenesis were not affected. However, angiogenic sprouting of new blood vessels was not observed in response to AdVEGF-C or AAV-VEGF-C. These results show that virally produced VEGF-C induces blood vessel changes, including vascular leak, but its angiogenic potency is much reduced compared with VEGF in normal skin. %B FASEB J %V 16 %P 1041 - 9 %8 2002/Jul/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/12087065 %N 9 %! The FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology %0 Journal Article %J Circ Res %D 2001 %T Adenoviral expression of vascular endothelial growth factor-C induces lymphangiogenesis in the skin %A Enholm, B %A Karpanen, T %A Jeltsch, M %A Kubo, H %A Stenback, F %A Prevo, R %A Jackson, D G %A Yla-Herttuala, S %A Alitalo, K %X The growth of blood and lymphatic vasculature is mediated in part by secreted polypeptides of the vascular endothelial growth factor (VEGF) family. The prototype VEGF binds VEGF receptor (VEGFR)-1 and VEGFR-2 and is angiogenic, whereas VEGF-C, which binds to VEGFR-2 and VEGFR-3, is either angiogenic or lymphangiogenic in different assays. We used an adenoviral gene transfer approach to compare the effects of these growth factors in adult mice. Recombinant adenoviruses encoding human VEGF-C or VEGF were injected subcutaneously into C57Bl6 mice or into the ears of nude mice. Immunohistochemical analysis showed that VEGF-C upregulated VEGFR-2 and VEGFR-3 expression and VEGF upregulated VEGFR-2 expression at 4 days after injection. After 2 weeks, histochemical and immunohistochemical analysis, including staining for the lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), the vascular endothelial marker platelet-endothelial cell adhesion molecule-1 (PECAM-1), and the proliferating cell nuclear antigen (PCNA) revealed that VEGF-C induced mainly lymphangiogenesis in contrast to VEGF, which induced only angiogenesis. These results have significant implications in the planning of gene therapy using these growth factors. %B Circ Res %V 88 %P 623 - 9 %8 2001/Mar/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/11282897 %N 6 %! Circulation Research %0 Journal Article %J EMBO J %D 2001 %T Signalling via vascular endothelial growth factor receptor-3 is sufficient for lymphangiogenesis in transgenic mice %A Veikkola, T %A Jussila, L %A Makinen, T %A Karpanen, T %A Jeltsch, M %A Petrova, T V %A Kubo, H %A Thurston, G %A McDonald, D M %A Achen, M G %A Stacker, S A %A Alitalo, K %X Vascular endothelial growth factor receptor-3 (VEGFR-3) has an essential role in the development of embryonic blood vessels; however, after midgestation its expression becomes restricted mainly to the developing lymphatic vessels. The VEGFR-3 ligand VEGF-C stimulates lymphangiogenesis in transgenic mice and in chick chorioallantoic membrane. As VEGF-C also binds VEGFR-2, which is expressed in lymphatic endothelia, it is not clear which receptors are responsible for the lymphangiogenic effects of VEGF-C. VEGF-D, which binds to the same receptors, has been reported to induce angiogenesis, but its lymphangiogenic potential is not known. In order to define the lymphangiogenic signalling pathway we have created transgenic mice overexpressing a VEGFR-3-specific mutant of VEGF-C (VEGF-C156S) or VEGF-D in epidermal keratinocytes under the keratin 14 promoter. Both transgenes induced the growth of lymphatic vessels in the skin, whereas the blood vessel architecture was not affected. Evidence was also obtained that these growth factors act in a paracrine manner in vivo. These results demonstrate that stimulation of the VEGFR-3 signal transduction pathway is sufficient to induce specifically lymphangiogenesis in vivo. %B EMBO J %V 20 %P 1223 - 31 %8 2001/Mar/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/11250889 %N 6 %! The EMBO Journal %0 Journal Article %J EMBO J %D 2001 %T Vascular endothelial growth factor-C-mediated lymphangiogenesis promotes tumour metastasis %A Mandriota, S J %A Jussila, L %A Jeltsch, M %A Compagni, A %A Baetens, D %A Prevo, R %A Banerji, S %A Huarte, J %A Montesano, R %A Jackson, D G %A Orci, L %A Alitalo, K %A Christofori, G %A Pepper, M S %X Metastasis is a frequent and lethal complication of cancer. Vascular endothelial growth factor-C (VEGF-C) is a recently described lymphangiogenic factor. Increased expression of VEGF-C in primary tumours correlates with dissemination of tumour cells to regional lymph nodes. However, a direct role for VEGF-C in tumour lymphangiogenesis and subsequent metastasis has yet to be demonstrated. Here we report the establishment of transgenic mice in which VEGF-C expression, driven by the rat insulin promoter (Rip), is targeted to beta-cells of the endocrine pancreas. In contrast to wild-type mice, which lack peri-insular lymphatics, RipVEGF-C transgenics develop an extensive network of lymphatics around the islets of Langerhans. These mice were crossed with Rip1Tag2 mice, which develop pancreatic beta-cell tumours that are neither lymphangiogenic nor metastatic. Double-transgenic mice formed tumours surrounded by well developed lymphatics, which frequently contained tumour cell masses of beta-cell origin. These mice frequently developed pancreatic lymph node metastases. Our findings demonstrate that VEGF-C-induced lymphangiogenesis mediates tumour cell dissemination and the formation of lymph node metastases. %B EMBO J %V 20 %P 672 - 82 %8 2001/Feb/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/11179212 %N 4 %! The EMBO Journal %0 Journal Article %J Proc Natl Acad Sci U S A %D 1998 %T Vascular endothelial growth factor B (VEGF-B) binds to VEGF receptor-1 and regulates plasminogen activator activity in endothelial cells %A Olofsson, B %A Korpelainen, E %A Pepper, M S %A Mandriota, S J %A Aase, K %A Kumar, V %A Gunji, Y %A Jeltsch, M M %A Shibuya, M %A Alitalo, K %A Eriksson, U %X The vascular endothelial growth factor (VEGF) family has recently expanded by the identification and cloning of three additional members, namely VEGF-B, VEGF-C, and VEGF-D. In this study we demonstrate that VEGF-B binds selectively to VEGF receptor-1/Flt-1. This binding can be blocked by excess VEGF, indicating that the interaction sites on the receptor are at least partially overlapping. Mutating the putative VEGF receptor-1/Flt-1 binding determinants Asp63, Asp64, and Glu67 to alanine residues in VEGF-B reduced the affinity to VEGF receptor-1 but did not abolish binding. Mutational analysis of conserved cysteines contributing to VEGF-B dimer formation suggest a structural conservation with VEGF and platelet-derived growth factor. Proteolytic processing of the 60-kDa VEGF-B186 dimer results in a 34-kDa dimer containing the receptor-binding epitopes. The binding of VEGF-B to its receptor on endothelial cells leads to increased expression and activity of urokinase type plasminogen activator and plasminogen activator inhibitor 1, suggesting a role for VEGF-B in the regulation of extracellular matrix degradation, cell adhesion, and migration. %B Proc Natl Acad Sci U S A %V 95 %P 11709 - 14 %8 1998/Sep/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/9751730 %N 20 %! Proceedings of the National Academy of Sciences of the United States of America %0 Journal Article %J J Cell Physiol %D 1998 %T Vascular endothelial growth factor (VEGF)-C synergizes with basic fibroblast growth factor and VEGF in the induction of angiogenesis in vitro and alters endothelial cell extracellular proteolytic activity %A Pepper, M S %A Mandriota, S J %A Jeltsch, M %A Kumar, V %A Alitalo, K %X Vascular endothelial growth factor-C (VEGF-C) is a recently characterized member of the VEGF family of angiogenic polypeptides. We demonstrate here that VEGF-C is angiogenic in vitro when added to bovine aortic or lymphatic endothelial (BAE and BLE) cells but has little or no effect on bovine microvascular endothelial (BME) cells. As reported previously for VEGF, VEGF-C and basic fibroblast growth factor (bFGF) induced a synergistic in vitro angiogenic response in all three cells lines. Unexpectedly, VEGF and VEGF-C also synergized in the in vitro angiogenic response when assessed on BAE cells. Characterization of VEGF receptor (VEGFR) expression revealed that BME, BAE, and BLE cell lines express VEGFR-1 and -2, whereas of the three cell lines assessed, only BAE cells express VEGFR-3. We also demonstrate that VEGF-C increases plasminogen activator (PA) activity in the three bovine endothelial cell lines and that this is accompanied by a concomitant increase in PA inhibitor-1. Addition of alpha2-antiplasmin to BME cells co-treated with bFGF and VEGF-C partially inhibited collagen gel invasion. These results demonstrate, first, that by acting in concert with bFGF or VEGF, VEGF-C has a potent synergistic effect on the induction of angiogenesis in vitro and, second, that like VEGF and bFGF, VEGF-C is capable of altering endothelial cell extracellular proteolytic activity. These observations also highlight the notion of context, i.e., that the activity of an angiogenesis-regulating cytokine depends on the presence and concentration of other cytokines in the pericellular environment of the responding endothelial cell. %B J Cell Physiol %V 177 %P 439 - 52 %8 1998/Dec/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/9808152 %N 3 %! Journal of Cellular Physiology %0 Journal Article %J J Biol Chem %D 1997 %T Genomic organization of human and mouse genes for vascular endothelial growth factor C %A Chilov, D %A Kukk, E %A Taira, S %A Jeltsch, M %A Kaukonen, J %A Palotie, A %A Joukov, V %A Alitalo, K %X We report here the cloning and characterization of human and mouse genes for vascular endothelial growth factor C (VEGF-C), a newly isolated member of the vascular endothelial growth factor/platelet-derived growth factor (VEGF/PDGF) family. Both VEGF-C genes comprise over 40 kilobase pairs of genomic DNA and consist of seven exons, all containing coding sequences. The VEGF homology domain of VEGF-C is encoded by exons 3 and 4. Exons 5 and 7 encode cysteine-rich motifs of the type C6C10CRC, and exon 6 encodes additional C10CXCXC motifs typical of a silk protein. A putative alternatively spliced rare RNA form lacking exon 4 was identified in human fibrosarcoma cells, and a major transcription start site was located in the human VEGF-C gene 523 base pairs upstream of the translation initiation codon. The upstream promoter sequences contain conserved putative binding sites for Sp-1, AP-2, and NF-kappaB transcription factors but no TATA box, and they show promoter activity when transfected into cells. The VEGF-C gene structure is thus assembled from exons encoding propeptides and distinct cysteine-rich domains in addition to the VEGF homology domain, and it shows both similarities and distinct differences in comparison with other members of the VEGF/PDGF gene family. %B J Biol Chem %V 272 %P 25176 - 83 %8 1997/Oct/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/9312130 %N 40 %! The Journal of Biological Chemistry %0 Journal Article %J J Cell Physiol %D 1997 %T Vascular endothelial growth factors VEGF-B and VEGF-C %A Joukov, V %A Kaipainen, A %A Jeltsch, M %A Pajusola, K %A Olofsson, B %A Kumar, V %A Eriksson, U %A Alitalo, K %B J Cell Physiol %V 173 %P 211 - 5 %8 1997/Nov/ %G eng %U http://view.ncbi.nlm.nih.gov/pubmed/9365524 %N 2 %! Journal of Cellular Physiology