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Takashi Morita - One of the best experts on this subject based on the ideXlab platform.
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snake venom vascular Endothelial Growth Factors vegf fs exclusively vary their structures and functions among species
Journal of Biological Chemistry, 2009Co-Authors: Yasuo Yamazaki, Yukiko Matsunaga, Yuko Tokunaga, Shinya Obayashi, Mai Saito, Takashi MoritaAbstract:Vascular Endothelial Growth factor (VEGF-A) and its family proteins are crucial regulators of blood vessel formation and vascular permeability. Snake venom has recently been shown to be an exogenous source of unique VEGF (known as VEGF-F), and now, two types of VEGF-F with distinct biochemical properties have been reported. Here, we show that VEGF-Fs (venom-type VEGFs) are highly variable in structure and function among species, in contrast to endogenous tissue-type VEGFs (VEGF-As) of snakes. Although the structures of tissue-type VEGFs are highly conserved among venomous snake species and even among all vertebrates, including humans, those of venom-type VEGFs are extensively variegated, especially in the regions around receptor-binding loops and C-terminal putative coreceptor-binding regions, indicating that highly frequent variations are located around functionally key regions of the proteins. Genetic analyses suggest that venom-type VEGF gene may have developed from a tissue-type gene and that the unique sequence of its C-terminal region was generated by an alteration in the translation frame in the corresponding exons. We further verified that a novel venom-type VEGF from Bitis arietans displays unique properties distinct from already known VEGFs. Our results may provide evidence of a novel mechanism causing the generation of multiple snake toxins and also of a new model of molecular evolution.
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Molecular and functional diversity of vascular Endothelial Growth Factors
Molecular Diversity, 2006Co-Authors: Yasuo Yamazaki, Takashi MoritaAbstract:Members of the vascular Endothelial Growth factor (VEGF) family are crucial regulators of neovascularization and are classified as cystine knot Growth Factors that specifically bind cellular receptor tyrosine kinases VEGFR-1, VEGFR-2, and VEGFR-3 with high but variable affinity and selectivity. The VEGF family has recently been expanded and currently comprises seven members: VEGF-A, VEGF-B, placenta Growth factor (PlGF), VEGF-C, VEGF-D, viral VEGF (also known as VEGF-E), and snake venom VEGF (also known as VEGF-F). Although all members are structurally homologous, there is molecular diversity among the subtypes, and several isoforms, such as VEGF-A, VEGF-B, and PlGF, are generated by alternative exon splicing. These splicing isoforms exhibit differing properties, particularly in binding to co-receptor neuropilins and heparin. VEGF family proteins play multiple physiological roles, such as angiogenesis and lymphangiogenesis, while exogenous members (viral and snake venom VEGFs) display activities that are unique in physiology and function. This review will highlight the molecular and functional diversity of VEGF family proteins.
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crystal structures of novel vascular Endothelial Growth Factors vegf from snake venoms insight into selective vegf binding to kinase insert domain containing receptor but not to fms like tyrosine kinase 1
Journal of Biological Chemistry, 2005Co-Authors: Kyoko Suto, Yasuo Yamazaki, Takashi Morita, Hiroshi MizunoAbstract:Abstract Vascular Endothelial Growth factor-A (VEGF-A165) exerts multiple effects upon binding to the fms-like tyrosine kinase-1 (Flt-1) and the kinase insert domain-containing receptor (KDR). We recently identified two novel snake venom VEGFs (vammin and VR-1) having unique properties. These VEGFs, designated VEGF-Fs, are highly specific ligands for the kinase insert domain-containing receptor and exhibit potent biological activity both in vitro and in vivo when compared with VEGF-A165. Here, we solved the crystal structures of vammin and VR-1 at 1.9 and 2.0 A resolutions, respectively. Both structures are very similar to each other, and these structures exhibit similar but significantly different features from the known structures of other VEGFs. These differences include a conformational difference in receptor-binding loop 3 caused by an amino acid residue insertion and a difference in surface potential on the possible binding surface for domain 3 of the receptor. These structural differences may be related to the highly selective ligand properties of VEGF-F.
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snake venom vascular Endothelial Growth Factors vegfs exhibit potent activity through their specific recognition of kdr vegf receptor 2
Journal of Biological Chemistry, 2003Co-Authors: Yasuo Yamazaki, Koji Takani, Hideko Atoda, Takashi MoritaAbstract:Abstract Vascular Endothelial Growth factor (VEGF165) exhibits multiple effects via the activation of two distinct Endothelial receptor tyrosine kinases: Flt-1 (fms-like tyrosine kinase-1) and KDR (kinase insert domain-containing receptor). KDR shows strong ligand-dependent tyrosine phosphorylation in comparison with Flt-1 and mainly mediates the mitogenic, angiogenic, and permeability-enhancing effects of VEGF165. Here we show the isolation of two VEGFs from viper venoms and the characterization of their unique biological properties. Snake venom VEGFs strongly stimulated proliferation of vascular Endothelial cells in vitro. Interestingly, the maximum activities were almost twice that of VEGF165. They also induced strong hypotension on rat arterial blood pressure compared with VEGF165 in vivo. A receptor binding assay revealed that snake venom VEGFs bound to KDR-IgG with high affinity (Kd = ∼0.1 nm) as well as to VEGF165 but did not interact with Flt-1, Flt-4, or neuropilin-1 at all. Our data clearly indicate that snake venom VEGFs act through the specific activation of KDR and show potent effects. Snake venom VEGFs are a highly specific ligand to KDR and form a new group of the VEGF family.
Seppo Ylaherttuala - One of the best experts on this subject based on the ideXlab platform.
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differential regulation of vascular Endothelial Growth Factors by promoter targeted shrnas
Molecular therapy. Nucleic acids, 2015Co-Authors: Nihay Lahamkaram, Marianne Lalli, Nastasia Leinonen, Seppo YlaherttualaAbstract:Vascular Endothelial Growth Factors (VEGFs) and their receptors (VEGF-R) are central regulators of vasculogenesis, angiogenesis, and lymphangiogenesis. They contribute to many vascular-related pathologies, and hence VEGF-targeted therapies have been widely sought after. In this study, the authors investigated the ability of promoter-targeted small hairpin RNAs (shRNAs) to regulate VEGF-A, VEGF-C and VEGF-R1 in different cell lines. The authors identified shRNAs that can upregulate hVEGF-C at both the mRNA and protein levels, and differentially regulate hVEGF-A depending on the cell type. Likewise, the authors identified shRNA that downregulated VEGF-R1 gene expression. Hence, promoter-targeted shRNAs can affect endogenous gene expression not only bimodally, but also differentially in a cell-type specific manner. Importantly, all three genes tested were regulated by at least one shRNA, supporting the idea that nuclear RNA interference is a widespread phenomenon. The level of regulation across the panel of shRNAs varied maximally from a 2.2-fold increase to a 4-fold decrease. This level of change should be useful in fine-tuning and modulating target gene expression, which for potent molecules, such as VEGF-A and VEGF-C, can be very beneficial. These promoter-targeted shRNAs may facilitate the design and development of targeted, context-dependent strategies for both pro- and antiangiogenic therapies for the treatment of vascular-related pathologies.
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the impact of the receptor binding profiles of the vascular Endothelial Growth Factors on their angiogenic features
Biochimica et Biophysica Acta, 2014Co-Authors: Tiina Nieminen, Kari Alitalo, Pyry I Toivanen, Nina Rintanen, Tommi Heikura, Suvi Jauhiainen, Kari J Airenne, Varpu Marjomaki, Seppo YlaherttualaAbstract:Abstract Background Vascular Endothelial Growth Factors (VEGFs) are potential therapeutic agents for treatment of ischemic diseases. Their angiogenic effects are mainly mediated through VEGF receptor 2 (VEGFR2). Methods Receptor binding, signaling, and biological efficacy of several VEGFR2 ligands were compared to determine their characteristics regarding angiogenic activity and vascular permeability. Results Tested VEGFR2 ligands induced receptor tyrosine phosphorylation with different efficacy depending on their binding affinities. However, the tyrosine phosphorylation pattern and the activation of the major downstream signaling pathways were comparable. The maximal angiogenic effect stimulated by different VEGFR2 ligands was dependent on their ability to bind to co-receptor Neuropilin (Nrp), which was shown to form complexes with VEGFR2. The ability of these VEGFR2 ligands to induce vascular permeability was dependent on their concentration and VEGFR2 affinity, but not on Nrp binding. Conclusions VEGFR2 activation alone is sufficient for inducing Endothelial cell proliferation, formation of tube-like structures and vascular permeability. The level of VEGFR2 activation is dependent on the binding properties of the ligand used. However, closely similar activation pattern of the receptor kinase domain is seen with all VEGFR2 ligands. Nrp binding strengthens the angiogenic potency without increasing vascular permeability. General significance This study sheds light on how different structurally closely related VEGFR2 ligands bind to and signal via VEGFR2/Nrp complex to induce angiogenesis and vascular permeability. The knowledge of this study could be used for designing VEGFR2/Nrp ligands with improved therapeutic properties.
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cardiovascular gene therapy with vascular Endothelial Growth Factors
Gene, 2013Co-Authors: Seppo YlaherttualaAbstract:Abstract Therapeutic angiogenesis with vascular Endothelial Growth Factors (VEGFs) is a promising approach for the treatment of ischemic myocardium and peripheral skeletal muscles. Preclinical studies in large animals have clearly demonstrated safety and efficacy of VEGF gene therapy in clinically relevant disease models. However, first clinical trials with intravascular delivery of VEGF vector constructs have only resulted in limited benefits to the patients. Second generation VEGF-based gene therapy trials are based on direct intramyocardial and intraskeletal muscle injections in order to achieve better transfection efficiency and more targeted effects. Phase I/II studies are currently ongoing to test safety, feasibility and efficacy of these improved approaches in patients with severe cardiovascular diseases.
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vascular Endothelial Growth Factors
Journal of the American College of Cardiology, 2007Co-Authors: Seppo Ylaherttuala, Tuomas T Rissanen, Ismo Vajanto, Juha HartikainenAbstract:Vascular Endothelial Growth Factors: Biology and Current Status of Clinical Applications in Cardiovascular Medicine Seppo Yla-Herttuala, FESC, Tuomas T. Rissanen, Ismo Vajanto, Juha Hartikainen Members of the vascular Endothelial Growth factor family are among the most powerful modulators of vascular biology. They regulate vasculogenesis, angiogenesis, and vascular maintenance during embryogenesis and in adults. Because of their profound effects on blood vessels, vascular Endothelial Growth Factors have received much attention regarding their potential therapeutic use in cardiovascular medicine. Here we review their biology, effects and current status of clinical applications. Members of the vascular Endothelial Growth factor (VEGF) family are among the most powerful modulators of vascular biology. They regulate vasculogenesis, angiogenesis, and vascular maintenance during embryogenesis and in adults. Because of their profound effects on blood vessels, VEGFs have received much attention regarding their potential therapeutic use in cardiovascular medicine, especially for therapeutic vascular Growth in myocardial and peripheral ischemia. However, completed randomized controlled VEGF trials have not provided convincing evidence of clinical efficacy. On the other hand, recent preclinical proangiogenic VEGF studies have given insight, and anti-VEGF studies have shown that the disturbance of vascular homeostasis by blocking VEGF-A may lead to Endothelial dysfunction and adverse vascular effects. Excess VEGF-A may contribute to neovascularization of atherosclerotic lesions but, currently, there is no evidence that transient overexpression by gene transfer could lead to plaque destabilization. Here, we review the biology and effects of VEGFs as well as the current status of clinical applications and future perspectives of the therapeutic use of VEGFs in cardiovascular medicine.
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vascular Endothelial Growth Factors biology and current status of clinical applications in cardiovascular medicine
Journal of the American College of Cardiology, 2007Co-Authors: Seppo Ylaherttuala, Tuomas T Rissanen, Ismo Vajanto, Juha HartikainenAbstract:Members of the vascular Endothelial Growth factor (VEGF) family are among the most powerful modulators of vascular biology. They regulate vasculogenesis, angiogenesis, and vascular maintenance during embryogenesis and in adults. Because of their profound effects on blood vessels, VEGFs have received much attention regarding their potential therapeutic use in cardiovascular medicine, especially for therapeutic vascular Growth in myocardial and peripheral ischemia. However, completed randomized controlled VEGF trials have not provided convincing evidence of clinical efficacy. On the other hand, recent preclinical proangiogenic VEGF studies have given insight, and anti-VEGF studies have shown that the disturbance of vascular homeostasis by blocking VEGF-A may lead to Endothelial dysfunction and adverse vascular effects. Excess VEGF-A may contribute to neovascularization of atherosclerotic lesions but, currently, there is no evidence that transient overexpression by gene transfer could lead to plaque destabilization. Here, we review the biology and effects of VEGFs as well as the current status of clinical applications and future perspectives of the therapeutic use of VEGFs in cardiovascular medicine.
Kari Alitalo - One of the best experts on this subject based on the ideXlab platform.
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the impact of the receptor binding profiles of the vascular Endothelial Growth Factors on their angiogenic features
Biochimica et Biophysica Acta, 2014Co-Authors: Tiina Nieminen, Kari Alitalo, Pyry I Toivanen, Nina Rintanen, Tommi Heikura, Suvi Jauhiainen, Kari J Airenne, Varpu Marjomaki, Seppo YlaherttualaAbstract:Abstract Background Vascular Endothelial Growth Factors (VEGFs) are potential therapeutic agents for treatment of ischemic diseases. Their angiogenic effects are mainly mediated through VEGF receptor 2 (VEGFR2). Methods Receptor binding, signaling, and biological efficacy of several VEGFR2 ligands were compared to determine their characteristics regarding angiogenic activity and vascular permeability. Results Tested VEGFR2 ligands induced receptor tyrosine phosphorylation with different efficacy depending on their binding affinities. However, the tyrosine phosphorylation pattern and the activation of the major downstream signaling pathways were comparable. The maximal angiogenic effect stimulated by different VEGFR2 ligands was dependent on their ability to bind to co-receptor Neuropilin (Nrp), which was shown to form complexes with VEGFR2. The ability of these VEGFR2 ligands to induce vascular permeability was dependent on their concentration and VEGFR2 affinity, but not on Nrp binding. Conclusions VEGFR2 activation alone is sufficient for inducing Endothelial cell proliferation, formation of tube-like structures and vascular permeability. The level of VEGFR2 activation is dependent on the binding properties of the ligand used. However, closely similar activation pattern of the receptor kinase domain is seen with all VEGFR2 ligands. Nrp binding strengthens the angiogenic potency without increasing vascular permeability. General significance This study sheds light on how different structurally closely related VEGFR2 ligands bind to and signal via VEGFR2/Nrp complex to induce angiogenesis and vascular permeability. The knowledge of this study could be used for designing VEGFR2/Nrp ligands with improved therapeutic properties.
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Interactions between VEGFR and Notch signaling pathways in Endothelial and neural cells
Cellular and Molecular Life Sciences, 2013Co-Authors: Jean Léon Thomas, Kasey Baker, Jinah Han, Charles Calvo, Harri Nurmi, Anne C. Eichmann, Kari AlitaloAbstract:Notch cell interaction mechanism governs cell fate decisions in many different cell contexts throughout the lifetime of all Metazoan species. It links the fate of one cell to that of its neighbors through cell-to-cell contacts, and binding of Notch receptors expressed on one cell to their membrane bound ligands on an adjacent cell. Environmental cues, such as Growth Factors and extracellular matrix molecules, superimpose a dynamic regulation on this canonical Notch signaling pathway. In this review, we will focus on Notch signaling in the vertebrate vascular and nervous systems and examine its role in angiogenesis, neurogenesis, and neurovascular interactions. We will also highlight the molecular relationships of the Notch pathway with vascular Endothelial Growth Factors (VEGFs) and their high-affinity tyrosine kinase VEGF receptors, key regulators of both angiogenesis and neurogenesis.
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the biology of vascular Endothelial Growth Factors
Cardiovascular Research, 2005Co-Authors: Tuomas Tammela, Kari Alitalo, Berndt Enholm, Karri PaavonenAbstract:The discovery of the vascular Endothelial Growth factor (VEGF) family members VEGF, VEGF-B, placental Growth factor (PlGF), VEGF-C and VEGF-D and their receptors VEGFR-1, -2 and -3 has provided tools for studying the vascular system in development as well as in diseases ranging from ischemic heart disease to cancer. VEGF has been established as the prime angiogenic molecule during development, adult physiology and pathology. PlGF may primarily mediate arteriogenesis, the formation of collateral arteries from preexisting arterioles, with potential future therapeutic use in for example occlusive atherosclerotic disease. VEGF-C and VEGF-D are primarily lymphangiogenic Factors, but they can also induce angiogenesis in some conditions. While many studies have addressed the role of angiogenesis and the blood vasculature in human physiology, the lymphatic vascular system has until recently attracted very little attention. In this review, we will discuss recent advances in angiogenesis research and provide an overview of the molecular players involved in lymphangiogenesis.
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angiogenic responses of vascular Endothelial Growth Factors in periadventitial tissue
Human Gene Therapy, 2003Co-Authors: Shalini Bhardwaj, Kari Alitalo, Marcin Gruchala, Helena Viita, Ivana Kholova, Ilze Kokina, Marc G Achen, Steven A Stacker, Marja Hedman, Seppo YlaherttualaAbstract:Recent discovery of new members of the vascular Endothelial Growth factor (VEGF) family has generated much interest as to which members may be best suited for therapeutic angiogenesis in various tissues. In this study we evaluated angiogenic responses of the different members of the VEGF family in vivo using adenoviral gene transfer. Adenoviruses (1 × 109 plaque-forming units [pfu]) encoding for VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-CΔNΔC and VEGF-DΔNΔC (ΔNΔC are proteolytically cleaved forms) were transferred locally to the periadventitial space of the rabbit carotid arteries using a collar technique that allows efficient local transfection of the periadventitial tissue. Expression of the transfected VEGFs was confirmed by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Seven days after the gene transfer maximum neovessel formation was observed in VEGF-A-, VEGF-D-, and VEGF-DΔNΔC-transfected arteries. VEGF-CΔNΔC also showed angiogenic activity whereas VEGF-B was not effe...
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tumor associated macrophages express lymphatic Endothelial Growth Factors and are related to peritumoral lymphangiogenesis
American Journal of Pathology, 2002Co-Authors: Sebastian F Schoppmann, Kari Alitalo, Peter Birner, Johannes Stockl, Romana Kalt, Robert Ullrich, Carola Caucig, Ernst Kriehuber, Katalin Nagy, Dontscho KerjaschkiAbstract:Formation of lymphatic metastasis is the initial step of generalized spreading of tumor cells and predicts poor clinical prognosis. Lymphatic vessels generally arise within the peritumoral stroma, although the lymphangiopoietic vascular Endothelial Growth Factors (VEGF)-C and -D are produced by tumor cells. In a carefully selected collection of human cervical cancers (stage pT1b1) we demonstrate by quantitative immunohistochemistry and in situ hybridization that density of lymphatic microvessels is significantly increased in peritumoral stroma, and that a subset of stromal cells express large amounts of VEGF-C and VEGF-D. The density of cells producing these vascular Growth Factors correlates with peritumoral inflammatory stroma reaction, lymphatic microvessel density, and indirectly with peritumoral carcinomatous lymphangiosis and frequency of lymph node metastasis. The VEGF-C- and VEGF-D-producing stroma cells were identified in situ as a subset of activated tumor-associated macrophages (TAMs) by expression of a panel of macrophage-specific markers, including CD68, CD23, and CD14. These TAMs also expressed the VEGF-C- and VEGF-D-specific tyrosine kinase receptor VEGFR-3. As TAMs are derived from monocytes in the circulation, a search in peripheral blood for candidate precursors of VEGFR-3-expressing TAMs revealed a subfraction of CD14-positive, VEGFR-3-expressing monocytes, that, however, failed to express VEGF-C and VEGF-D. Only after in vitro incubation with tumor necrosis factor-α, lipopolysaccharide, or VEGF-D did these monocytes start to synthesize VEGF-C de novo. In conclusion VEGF-C-expressing TAMs play a novel role in peritumoral lymphangiogenesis and subsequent dissemination in human cancer.
Yasuo Yamazaki - One of the best experts on this subject based on the ideXlab platform.
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snake venom vascular Endothelial Growth Factors vegf fs exclusively vary their structures and functions among species
Journal of Biological Chemistry, 2009Co-Authors: Yasuo Yamazaki, Yukiko Matsunaga, Yuko Tokunaga, Shinya Obayashi, Mai Saito, Takashi MoritaAbstract:Vascular Endothelial Growth factor (VEGF-A) and its family proteins are crucial regulators of blood vessel formation and vascular permeability. Snake venom has recently been shown to be an exogenous source of unique VEGF (known as VEGF-F), and now, two types of VEGF-F with distinct biochemical properties have been reported. Here, we show that VEGF-Fs (venom-type VEGFs) are highly variable in structure and function among species, in contrast to endogenous tissue-type VEGFs (VEGF-As) of snakes. Although the structures of tissue-type VEGFs are highly conserved among venomous snake species and even among all vertebrates, including humans, those of venom-type VEGFs are extensively variegated, especially in the regions around receptor-binding loops and C-terminal putative coreceptor-binding regions, indicating that highly frequent variations are located around functionally key regions of the proteins. Genetic analyses suggest that venom-type VEGF gene may have developed from a tissue-type gene and that the unique sequence of its C-terminal region was generated by an alteration in the translation frame in the corresponding exons. We further verified that a novel venom-type VEGF from Bitis arietans displays unique properties distinct from already known VEGFs. Our results may provide evidence of a novel mechanism causing the generation of multiple snake toxins and also of a new model of molecular evolution.
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Molecular and functional diversity of vascular Endothelial Growth Factors
Molecular Diversity, 2006Co-Authors: Yasuo Yamazaki, Takashi MoritaAbstract:Members of the vascular Endothelial Growth factor (VEGF) family are crucial regulators of neovascularization and are classified as cystine knot Growth Factors that specifically bind cellular receptor tyrosine kinases VEGFR-1, VEGFR-2, and VEGFR-3 with high but variable affinity and selectivity. The VEGF family has recently been expanded and currently comprises seven members: VEGF-A, VEGF-B, placenta Growth factor (PlGF), VEGF-C, VEGF-D, viral VEGF (also known as VEGF-E), and snake venom VEGF (also known as VEGF-F). Although all members are structurally homologous, there is molecular diversity among the subtypes, and several isoforms, such as VEGF-A, VEGF-B, and PlGF, are generated by alternative exon splicing. These splicing isoforms exhibit differing properties, particularly in binding to co-receptor neuropilins and heparin. VEGF family proteins play multiple physiological roles, such as angiogenesis and lymphangiogenesis, while exogenous members (viral and snake venom VEGFs) display activities that are unique in physiology and function. This review will highlight the molecular and functional diversity of VEGF family proteins.
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crystal structures of novel vascular Endothelial Growth Factors vegf from snake venoms insight into selective vegf binding to kinase insert domain containing receptor but not to fms like tyrosine kinase 1
Journal of Biological Chemistry, 2005Co-Authors: Kyoko Suto, Yasuo Yamazaki, Takashi Morita, Hiroshi MizunoAbstract:Abstract Vascular Endothelial Growth factor-A (VEGF-A165) exerts multiple effects upon binding to the fms-like tyrosine kinase-1 (Flt-1) and the kinase insert domain-containing receptor (KDR). We recently identified two novel snake venom VEGFs (vammin and VR-1) having unique properties. These VEGFs, designated VEGF-Fs, are highly specific ligands for the kinase insert domain-containing receptor and exhibit potent biological activity both in vitro and in vivo when compared with VEGF-A165. Here, we solved the crystal structures of vammin and VR-1 at 1.9 and 2.0 A resolutions, respectively. Both structures are very similar to each other, and these structures exhibit similar but significantly different features from the known structures of other VEGFs. These differences include a conformational difference in receptor-binding loop 3 caused by an amino acid residue insertion and a difference in surface potential on the possible binding surface for domain 3 of the receptor. These structural differences may be related to the highly selective ligand properties of VEGF-F.
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snake venom vascular Endothelial Growth Factors vegfs exhibit potent activity through their specific recognition of kdr vegf receptor 2
Journal of Biological Chemistry, 2003Co-Authors: Yasuo Yamazaki, Koji Takani, Hideko Atoda, Takashi MoritaAbstract:Abstract Vascular Endothelial Growth factor (VEGF165) exhibits multiple effects via the activation of two distinct Endothelial receptor tyrosine kinases: Flt-1 (fms-like tyrosine kinase-1) and KDR (kinase insert domain-containing receptor). KDR shows strong ligand-dependent tyrosine phosphorylation in comparison with Flt-1 and mainly mediates the mitogenic, angiogenic, and permeability-enhancing effects of VEGF165. Here we show the isolation of two VEGFs from viper venoms and the characterization of their unique biological properties. Snake venom VEGFs strongly stimulated proliferation of vascular Endothelial cells in vitro. Interestingly, the maximum activities were almost twice that of VEGF165. They also induced strong hypotension on rat arterial blood pressure compared with VEGF165 in vivo. A receptor binding assay revealed that snake venom VEGFs bound to KDR-IgG with high affinity (Kd = ∼0.1 nm) as well as to VEGF165 but did not interact with Flt-1, Flt-4, or neuropilin-1 at all. Our data clearly indicate that snake venom VEGFs act through the specific activation of KDR and show potent effects. Snake venom VEGFs are a highly specific ligand to KDR and form a new group of the VEGF family.
Gianni Marone - One of the best experts on this subject based on the ideXlab platform.
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production of vascular Endothelial Growth Factors from human lung macrophages induced by group iia and group x secreted phospholipases a2
Journal of Immunology, 2010Co-Authors: Francescopaolo Granata, Rosaria I Staiano, Domenico Ribatti, Annunziata Frattini, Stefania Loffredo, Angelica Petraroli, Rob C Oslund, Michael H Gelb, Gerard Lambeau, Gianni MaroneAbstract:Angiogenesis and lymphangiogenesis mediated by vascular Endothelial Growth Factors (VEGFs) are main features of chronic inflammation and tumors. Secreted phospholipases A2 (sPLA2s) are overexpressed in inflammatory lung diseases and cancer and they activate inflammatory cells by enzymatic and receptor-mediated mechanisms. We investigated the effect of sPLA2s on the production of VEGFs from human macrophages purified from the lung tissue of patients undergoing thoracic surgery. Primary macrophages express VEGF-A, VEGF-B, VEGF-C, and VEGF-D at both mRNA and protein level. Two human sPLA2s (group IIA and group X) induced the expression and release of VEGF-A and VEGF-C from macrophages. Enzymatically-inactive sPLA2s were as effective as the active enzymes in inducing VEGF production. Me-Indoxam and RO092906A, two compounds that block receptor-mediated effects of sPLA2s, inhibited group X-induced release of VEGF-A. Inhibition of the MAPK p38 by SB203580 also reduced sPLA2-induced release of VEGF-A. Supernatants of group X-activated macrophages induced an angiogenic response in chorioallantoic membranes that was inhibited by Me-Indoxam. Stimulation of macrophages with group X sPLA2 in the presence of adenosine analogs induced a synergistic increase of VEGF-A release and inhibited TNF-α production through a cooperation between A2A and A3 receptors. These results demonstrate that sPLA2s induce production of VEGF-A and VEGF-C in human macrophages by a receptor-mediated mechanism independent from sPLA2 catalytic activity. Thus, sPLA2s may play an important role in inflammatory and/or neoplastic angiogenesis and lymphangiogenesis.
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vascular Endothelial Growth Factors synthesized by human lung mast cells exert angiogenic effects
The Journal of Allergy and Clinical Immunology, 2009Co-Authors: Aikaterini Detoraki, Amato De Paulis, Nella Prevete, Arturo Genovese, Rosaria I Staiano, Francescopaolo Granata, Giorgio Giannattasio, Domenico Ribatti, Massimo Triggiani, Gianni MaroneAbstract:Background Angiogenesis and lymphangiogenesis are critical for several allergic, inflammatory, and neoplastic disorders. Mast cells infiltrate the sites of inflammation and tumors. Objective We sought to characterize the expression and functions of vascular Endothelial Growth Factors (VEGFs) and their receptors (VEGFRs) in human mast cells. Methods VEGF expression was evaluated by means of RT-PCR and Western blotting in primary human lung mast cells and in the mast cell lines LAD-2 and HMC-1. Angiogenic activity of mast cell supernatants was determined by using the chick embryo chorioallantoic membrane assay. VEGFR expression was assessed by means of RT-PCR and flow cytometry. Modified Boyden chambers were used for chemotaxis assay. Results Human mast cells express VEGF-A, VEGF-B, VEGF-C, and VEGF-D at both the mRNA and protein level. Prostaglandin E 2 (PGE 2 ) enhanced the expression of VEGFA , VEGFB , and VEGFC , whereas an adenosine analog (5′-[N-ethylcarboxamido] adenosine [NECA]) increased VEGFA , VEGFC , and VEGFD expression. In addition, PGE 2 and NECA enhanced VEGF-A release, and supernatants of PGE 2 - and NECA-activated human lung mast cells induced angiogenic responses in the chorioallantoic membrane assay that were inhibited by an anti-VEGF-A antibody. Mast cells expressed mRNA for VEGFR1 and VEGFR2 . These receptors were present on the mast cell surface. VEGF-A 165 , VEGF-B 167 , VEGF-C, VEGF-D, and placental Growth factor 1 induced mast cell chemotaxis. These chemotactic effects were mediated by the activation of both VEGFR-1 and VEGFR-2. Conclusion Our data indicate that human mast cells are both a source and a target of angiogenic and lymphangiogenic Factors and therefore might play a role in inflammatory and neoplastic angiogenesis through the expression of several forms of VEGFs and their receptors.