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Heparin-Induced Changes of Vascular Endothelial Growth Factor (VEGF 165) Structure. Biomolecules 2023; 13:biom13010098. [PMID: 36671483 PMCID: PMC9856036 DOI: 10.3390/biom13010098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/28/2022] [Accepted: 01/01/2023] [Indexed: 01/06/2023] Open
Abstract
Vascular endothelial growth factor-A (VEGF-A), a secreted homodimeric glycoprotein, is a critical regulator of angiogenesis in normal and pathological states. The binding of heparin (HE) to VEGF165 (the major form of VEGF-A) modulates the angiogenesis-related cascade, but the mechanism of the observed changes at the structural level is still insufficiently explored. In the present study, we examined the effect of HE on the structural and physicochemical properties of recombinant human VEGF165 (rhVEGF165). The HE binding results in an increase of hydrophobic surface exposure in rhVEGF165 without changes in its secondary structure. Differential scanning calorimetry measurements for intact and HE-bound rhVEGF165 reveals the absence of any pronounced thermally induced transitions in the protein in the temperature range from 20 to 100 °C. The apolar area increase during the heparin binding explains the pronounced HE-induced oligomerization/aggregation of rhVEGF165, as studied by chemical glutaraldehyde cross-linking and dynamic light scattering. Molecular modeling and docking techniques were used to model the full structure of dimeric VEGF165 and to reveal putative molecular mechanisms underlying the function of the VEGF165/HE system. In general, the results obtained can be a basis for explaining the modulating effect of HE on the biological activity of VEGF-A.
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Ye X, Gaucher JF, Vidal M, Broussy S. A Structural Overview of Vascular Endothelial Growth Factors Pharmacological Ligands: From Macromolecules to Designed Peptidomimetics. Molecules 2021; 26:6759. [PMID: 34833851 PMCID: PMC8625919 DOI: 10.3390/molecules26226759] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 12/27/2022] Open
Abstract
The vascular endothelial growth factor (VEGF) family of cytokines plays a key role in vasculogenesis, angiogenesis, and lymphangiogenesis. VEGF-A is the main member of this family, alongside placental growth factor (PlGF), VEGF-B/C/D in mammals, and VEGF-E/F in other organisms. To study the activities of these growth factors under physiological and pathological conditions, resulting in therapeutic applications in cancer and age-related macular degeneration, blocking ligands have been developed. These have mostly been large biomolecules like antibodies. Ligands with high affinities, at least in the nanomolar range, and accurate structural data from X-ray crystallography and NMR spectroscopy have been described. They constitute the main focus of this overview, which evidences similarities and differences in their binding modes. For VEGF-A ligands, and to a limited extent also for PlGF, a transition is now observed towards developing smaller ligands like nanobodies and peptides. These include unnatural amino acids and chemical modifications for designed and improved properties, such as serum stability and greater affinity. However, this review also highlights the scarcity of such small molecular entities and the striking lack of small organic molecule ligands. It also shows the gap between the rather large array of ligands targeting VEGF-A and the general absence of ligands binding other VEGF members, besides some antibodies. Future developments in these directions are expected in the upcoming years, and the study of these growth factors and their promising therapeutic applications will be welcomed.
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Affiliation(s)
- Xiaoqing Ye
- Faculté de Pharmacie de Paris, Université de Paris, CiTCoM, 8038 CNRS, U 1268 INSERM, 75006 Paris, France; (X.Y.); (M.V.)
| | - Jean-François Gaucher
- Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie de Paris, Université de Paris, CiTCoM, 8038 CNRS, 75006 Paris, France;
| | - Michel Vidal
- Faculté de Pharmacie de Paris, Université de Paris, CiTCoM, 8038 CNRS, U 1268 INSERM, 75006 Paris, France; (X.Y.); (M.V.)
- Service Biologie du Médicament, Toxicologie, AP-HP, Hôpital Cochin, 75014 Paris, France
| | - Sylvain Broussy
- Faculté de Pharmacie de Paris, Université de Paris, CiTCoM, 8038 CNRS, U 1268 INSERM, 75006 Paris, France; (X.Y.); (M.V.)
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3
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Riccardi C, Napolitano E, Platella C, Musumeci D, Melone MAB, Montesarchio D. Anti-VEGF DNA-based aptamers in cancer therapeutics and diagnostics. Med Res Rev 2020; 41:464-506. [PMID: 33038031 DOI: 10.1002/med.21737] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 09/12/2020] [Accepted: 09/23/2020] [Indexed: 12/13/2022]
Abstract
The vascular endothelial growth factor (VEGF) family and its receptors play fundamental roles not only in physiological but also in pathological angiogenesis, characteristic of cancer progression. Aiming at finding putative treatments for several malignancies, various small molecules, antibodies, or protein-based drugs have been evaluated in vitro and in vivo as VEGF inhibitors, providing efficient agents approved for clinical use. Due to the high clinical importance of VEGF, also a great number of anti-VEGF nucleic acid-based aptamers-that is, oligonucleotides able to bind with high affinity and specificity a selected biological target-have been developed as promising agents in anticancer strategies. Notable research efforts have been made in optimization processes of the identified aptamers, searching for increased target affinity and/or bioactivity by exploring structural analogues of the lead compounds. This review is focused on recent studies devoted to the development of DNA-based aptamers designed to target VEGF. Their therapeutic potential as well as their significance in the construction of highly selective biosensors is here discussed.
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Affiliation(s)
- Claudia Riccardi
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.,Department of Advanced Medical and Surgical Sciences, 2nd Division of Neurology, Center for Rare Diseases and Inter-University Center for Research in Neurosciences, University of Campania Luigi Vanvitelli, Naples, Italy
| | - Ettore Napolitano
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy
| | - Chiara Platella
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy
| | - Domenica Musumeci
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.,Institute of Biostructures and Bioimages, Naples, Italy
| | - Mariarosa A B Melone
- Department of Advanced Medical and Surgical Sciences, 2nd Division of Neurology, Center for Rare Diseases and Inter-University Center for Research in Neurosciences, University of Campania Luigi Vanvitelli, Naples, Italy.,Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Daniela Montesarchio
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy
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4
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Zhang M, Liu Y, Cui F, Rankl C, Qin J, Guan Y, Guo X, Zhang B, Tang J. Interaction of vascular endothelial growth factor and heparin quantified by single molecule force spectroscopy. NANOSCALE 2020; 12:11927-11935. [PMID: 32458960 DOI: 10.1039/d0nr01570a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Heparin, as an effective anticoagulant, has been increasingly used in clinical practice, but the binding characteristics and influence of exogenous heparin on heparin-affinity proteins in the body are still unclear. Vascular endothelial growth factor A (VEGF-A) is a kind of protein with heparin affinity involved in the pathogenesis and progression of many angiogenesis-dependent diseases including cancer. As an important step in the angiogenesis-related cascade, it is necessary to clarify the interaction between VEGF165 (the major form of VEGF-A) and heparin. In this work, we investigated this interaction based on single molecule force spectroscopy (SMFS) and molecular dynamics (MD) simulation. From the SMFS study, binding forces between VEGF165 and heparin at different loading rates were quantified under near-physiological conditions. Meanwhile, the kinetic and thermodynamic parameters of the VEGF165/heparin complex dissociation process were also obtained. Results of MD simulation visually displayed the most likely binding conformation of VEGF165/heparin* complex, indicating that hydrogen bonding and hydrophobic interaction play a positive role in the binding between the two molecules. This work provides a new insight into the binding between VEGF165 and heparin and offers a research framework to study the interaction between heparin and multiple heparin affinity proteins, which is helpful for guiding the safe application of heparin in the clinic.
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Affiliation(s)
- Miaomiao Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. and University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Ying Liu
- College of Humanities & Information Changchun University of Technology, Changchun, 130122, P. R. China
| | - Fengchao Cui
- Key Laboratory of High-Performance Rubber and Its Composite Materials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Christian Rankl
- Research Center for Non Destructive Testing GmbH, Science Park 2/2. OG, Altenberger Straße 69, A-4040 Linz, Austria
| | - Juan Qin
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. and University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Yanxue Guan
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. and University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Xinyue Guo
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. and University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Bailin Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. and University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Jilin Tang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. and University of Science and Technology of China, Hefei, 230026, P. R. China
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5
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Garg N, Kumar P, Gadhave K, Giri R. The dark proteome of cancer: Intrinsic disorderedness and functionality of HIF-1α along with its interacting proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:371-403. [PMID: 31521236 DOI: 10.1016/bs.pmbts.2019.05.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The dark side of protein is the region (s) where molecular conformation is unknown. Intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs) are the dark matter of biology due to inability to visualize them using standard structure elucidation technique such as X-ray crystallography due to lack in diffraction signal. IDPs are the functionally important class of proteins with entire protein or its parts lack ordered three-dimensional structure. Computational studies have predicted that nearly one-third of the human proteome is disordered, which gives the enormous flexibility and functional diversity to proteins. The conserved residues and elements in disordered proteins are critical for function and might be parts of peptide motifs or protein-protein interaction interfaces. For example, regions of proteins that are involved in disorder-based molecular recognition are known as molecular recognition features (MoRFs). Generally, MoRFs could undergo disorder to order transition or vice versa at interaction with specific partners. Hypoxia inducible factor 1α (HIF-1α) is a master transcriptional regulator involved in response to hypoxia, which is associated with many pathological conditions. Importantly, HIF-1α regulates various steps of cancer progression such as cell survival, tumor cell invasion, and metastasis. In this chapter, we have extensively analyzed the molecular recognition features and their relationship with disordered regions and associated structural islands of HIF-1α. We had also analyzed the disorderness and MoRFs of HIF-1α primary interaction partners that are enriched in IDPRs and MoRFs giving their role in protein-protein interaction and cancer regulation.
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Affiliation(s)
- Neha Garg
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India
| | - Prateek Kumar
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India
| | - Kundlik Gadhave
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India
| | - Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India.
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Peach CJ, Mignone VW, Arruda MA, Alcobia DC, Hill SJ, Kilpatrick LE, Woolard J. Molecular Pharmacology of VEGF-A Isoforms: Binding and Signalling at VEGFR2. Int J Mol Sci 2018; 19:E1264. [PMID: 29690653 PMCID: PMC5979509 DOI: 10.3390/ijms19041264] [Citation(s) in RCA: 262] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/14/2018] [Accepted: 04/16/2018] [Indexed: 02/07/2023] Open
Abstract
Vascular endothelial growth factor-A (VEGF-A) is a key mediator of angiogenesis, signalling via the class IV tyrosine kinase receptor family of VEGF Receptors (VEGFRs). Although VEGF-A ligands bind to both VEGFR1 and VEGFR2, they primarily signal via VEGFR2 leading to endothelial cell proliferation, survival, migration and vascular permeability. Distinct VEGF-A isoforms result from alternative splicing of the Vegfa gene at exon 8, resulting in VEGFxxxa or VEGFxxxb isoforms. Alternative splicing events at exons 5⁻7, in addition to recently identified posttranslational read-through events, produce VEGF-A isoforms that differ in their bioavailability and interaction with the co-receptor Neuropilin-1. This review explores the molecular pharmacology of VEGF-A isoforms at VEGFR2 in respect to ligand binding and downstream signalling. To understand how VEGF-A isoforms have distinct signalling despite similar affinities for VEGFR2, this review re-evaluates the typical classification of these isoforms relative to the prototypical, “pro-angiogenic” VEGF165a. We also examine the molecular mechanisms underpinning the regulation of VEGF-A isoform signalling and the importance of interactions with other membrane and extracellular matrix proteins. As approved therapeutics targeting the VEGF-A/VEGFR signalling axis largely lack long-term efficacy, understanding these isoform-specific mechanisms could aid future drug discovery efforts targeting VEGF receptor pharmacology.
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Affiliation(s)
- Chloe J Peach
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
| | - Viviane W Mignone
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
- CAPES-University of Nottingham Programme in Drug Discovery, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
| | - Maria Augusta Arruda
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
- CAPES-University of Nottingham Programme in Drug Discovery, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
| | - Diana C Alcobia
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
| | - Laura E Kilpatrick
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
| | - Jeanette Woolard
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands NG7 2UH, UK.
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7
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Jeong KW, Jeong MC, Jin B, Kim Y. Relationship between Structural Flexibility and Function in the C-Terminal Region of the Heparin-Binding Domain of VEGF165. Biochemistry 2013; 52:8823-32. [DOI: 10.1021/bi4011682] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ki-Woong Jeong
- Department of Bioscience
and Biotechnology and Bio/Molecular Informatics
Center, Institute of KU Biotechnology, Konkuk University, Seoul 143-701, Korea
| | - Min-Cheol Jeong
- Department of Bioscience
and Biotechnology and Bio/Molecular Informatics
Center, Institute of KU Biotechnology, Konkuk University, Seoul 143-701, Korea
| | - Bonghwan Jin
- Department of Bioscience
and Biotechnology and Bio/Molecular Informatics
Center, Institute of KU Biotechnology, Konkuk University, Seoul 143-701, Korea
| | - Yangmee Kim
- Department of Bioscience
and Biotechnology and Bio/Molecular Informatics
Center, Institute of KU Biotechnology, Konkuk University, Seoul 143-701, Korea
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8
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Mammadov R, Mammadov B, Guler MO, Tekinay AB. Growth factor binding on heparin mimetic peptide nanofibers. Biomacromolecules 2012; 13:3311-9. [PMID: 22963465 DOI: 10.1021/bm3010897] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Immobilization of growth factors in scaffolds is important for controlling their dose and bioactivity for regenerative medicine applications. Although numerous covalent and noncovalent immobilization strategies have been proposed, better growth factor loading and dose control inside the scaffold is necessary. Nature of the binding site on the growth factor interacting with scaffold is critical for preserving and achieving maximal growth factor functionality, which has been a relatively less emphasized issue in previous studies. We recently reported heparin mimetic peptide nanofibers, which mimic chemistry of heparan sulfates. Heparin mimetic nanofibers were shown to bind to vascular endothelial growth factor (VEGF) and direct endothelial cells to angiogenesis. Here, we further investigated interactions between heparin mimetic peptide nanofibers and growth factors. We tested bioactivity of the nanofiber bound growth factors in order to understand the potential use of these peptide nanofiber scaffolds as analogues of heparan sulfates. We observed that heparin mimetic peptide nanofibers demonstrate better binding profiles to VEGF, hepatocyte growth factor (HGF), and fibroblast growth factor-2 (FGF-2) than control peptide nanofibers. We also identified that the heparin-binding domain of VEGF is critical for its interaction with these nanofibers. However, the heparin-binding site is not indispensable for binding of all growth factors to nanofibers. We also showed that binding of growth factors to nanofibers does not cause any loss in bioactivity through in vitro cell culture assays with PC-12 cells. These results reveal that heparin mimetic peptide nanofibers can effectively mimic heparan sulfates in extracellular matrix and provide an optimal milieu for spatial presentation of important growth factors. These properties make peptide nanofiber scaffolds promising materials for regenerative medicine applications through efficient and precisely controlled growth factor delivery.
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9
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Binding affinities of vascular endothelial growth factor (VEGF) for heparin-derived oligosaccharides. Biosci Rep 2012; 32:71-81. [PMID: 21658003 DOI: 10.1042/bsr20110077] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Heparin and HS (heparan sulfate) exert their wide range of biological activities by interacting with extracellular protein ligands. Among these important protein ligands are various angiogenic growth factors and cytokines. HS binding to VEGF (vascular endothelial growth factor) regulates multiple aspects of vascular development and function through its specific interaction with HS. Many studies have focused on HS-derived or HS-mimicking structures for the characterization of VEGF165 interaction with HS. Using a heparinase 1-prepared small library of heparin-derived oligosaccharides ranging from hexasaccharide to octadecasaccharide, we systematically investigated the heparin-specific structural features required for VEGF binding. We report the apparent affinities for the association between the heparin-derived oligosaccharides with both VEGF165 and VEGF55, a peptide construct encompassing exclusively the heparin-binding domain of VEGF165. An octasaccharide was the minimum size of oligosaccharide within the library to efficiently bind to both forms of VEGF and a tetradecasaccharide displayed an effective binding affinity to VEGF165 comparable to unfractionated heparin. The range of relative apparent binding affinities among VEGF and the panel of heparin-derived oligosaccharides demonstrate that the VEGF binding affinity likely depends on the specific structural features of these oligosaccharides, including their degree of sulfation, sugar-ring stereochemistry and conformation. Notably, the unique 3-O-sulfo group found within the specific antithrombin binding site of heparin is not required for VEGF165 binding. These findings afford new insight into the inherent kinetics and affinities for VEGF association with heparin and heparin-derived oligosaccharides with key residue-specific modifications and may potentially benefit the future design of oligosaccharide-based anti-angiogenesis drugs.
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Sapay N, Cabannes É, Petitou M, Imberty A. Molecular model of human heparanase with proposed binding mode of a heparan sulfate oligosaccharide and catalytic amino acids. Biopolymers 2011; 97:21-34. [DOI: 10.1002/bip.21696] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/09/2011] [Accepted: 07/11/2011] [Indexed: 01/27/2023]
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11
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Sapay N, Cabannes E, Petitou M, Imberty A. Molecular modeling of the interaction between heparan sulfate and cellular growth factors: bringing pieces together. Glycobiology 2011; 21:1181-93. [PMID: 21572110 DOI: 10.1093/glycob/cwr052] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Heparan sulfate is a polysaccharide belonging to the glycaminoglycan family. It interacts with numerous proteins of the extracellular matrix, in particular cellular growth factors. The number of experimental protein-heparin sulfate complexes obtained by crystallography or nuclear magnetic resonance is limited. Alternatively, computational approaches can be employed. Generally, they restrain the conformation of the glycosidic rings and linkages in order to reduce the complexity of the problem. Modeling the interaction between protein and heparan sulfate is indeed challenging because of the large size of the fragment needed for a strong binding, the flexibility brought by the glycosidic rings and linkages and the high density of negative charges. We propose a two-step method based on molecular docking and molecular dynamics simulation. Molecular docking allows exploring the positioning of a rigid heparin sulfate fragment on the protein surface. Molecular dynamics refine selected docking models by explicitly representing solvent molecules and not restraining the polysaccharide backbone. The interaction of a hexamer of heparin sulfate was studied in interaction with fibroblast growth factor 2 and stromal cell-derived factor 1α. This approach shed light on the plasticity of the growth factors interacting with heparan sulfate. This approach can be extended to the study of other protein/glycosaminoglycan complexes.
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Affiliation(s)
- Nicolas Sapay
- Centre de Recherches sur les Macromolécules Végétales-CNRS, 601 rue de la Chimie, BP 53, 38041 Grenoble Cedex 9, France
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12
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Jeong KW, Lee JY, Lee SA, Yang SP, Ko H, Kang DI, Chae CB, Kim Y. Dynamics of a Heparin-Binding Domain of VEGF165 Complexed with Its Inhibitor Triamterene. Biochemistry 2011; 50:4843-54. [DOI: 10.1021/bi2000752] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Ki-Woong Jeong
- Department of Bioscience and Biotechnology and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea
| | - Jee-Young Lee
- Department of Bioscience and Biotechnology and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea
| | - Sung-Ah Lee
- Department of Bioscience and Biotechnology and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea
| | - Seung-Pil Yang
- Institute of Biomedical Science and Technology, Konkuk University, Seoul 143-701, Korea
| | - Hyunsook Ko
- Department of Bioscience and Biotechnology and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea
| | - Dong-Il Kang
- Department of Chemistry, Konkuk University, Seoul 143-701, Korea
| | - Chi-Bom Chae
- Institute of Biomedical Science and Technology, Konkuk University, Seoul 143-701, Korea
| | - Yangmee Kim
- Department of Bioscience and Biotechnology and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea
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13
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The heparin-binding domain confers diverse functions of VEGF-A in development and disease: a structure-function study. Biochem Soc Trans 2010; 37:1201-6. [PMID: 19909247 DOI: 10.1042/bst0371201] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The longer splice isoforms of VEGF (vascular endothelial growth factor)-A, including VEGF(164(165)), contain a highly basic HBD (heparin-binding domain). This domain allows these isoforms to interact with and localize to the HS (heparan sulfate)-rich extracellular matrix, and bind to the co-receptor Nrp-1 (neuropilin-1). Heparin-binding VEGF-A isoforms are critical for survival: mice engineered to express exclusively the non-heparin-binding VEGF(120) have diminished vascular branching during embryonic development and die from postnatal angiogenesis defects shortly after birth. Although it is thought that the HBD contributes to the diverse functions of VEGF-A in both physiological and pathological processes, little is known about the molecular features within this domain that enable these functions. In the present paper, we discuss the roles of the VEGF HBD in normal and disease conditions, with a particular focus on the VEGF(164(165)) isoform.
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14
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Structure-function analysis of VEGF receptor activation and the role of coreceptors in angiogenic signaling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:567-80. [PMID: 19761875 DOI: 10.1016/j.bbapap.2009.09.002] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 08/22/2009] [Accepted: 09/04/2009] [Indexed: 12/11/2022]
Abstract
Vascular endothelial growth factors (VEGFs) constitute a family of six polypeptides, VEGF-A, -B, -C, -D, -E and PlGF, that regulate blood and lymphatic vessel development. VEGFs specifically bind to three type V receptor tyrosine kinases (RTKs), VEGFR-1, -2 and -3, and to coreceptors such as neuropilins and heparan sulfate proteoglycans (HSPG). VEGFRs are activated upon ligand-induced dimerization mediated by the extracellular domain (ECD). A study using receptor constructs carrying artificial dimerization-promoting transmembrane domains (TMDs) showed that receptor dimerization is necessary, but not sufficient, for receptor activation and demonstrates that distinct orientation of receptor monomers is required to instigate transmembrane signaling. Angiogenic signaling by VEGF receptors also depends on cooperation with specific coreceptors such as neuropilins and HSPG. A number of VEGF isoforms differ in binding to coreceptors, and ligand-specific signal output is apparently the result of the specific coreceptor complex assembled by a particular VEGF isoform. Here we discuss the structural features of VEGF family ligands and their receptors in relation to their distinct signal output and angiogenic potential.
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Abstract
Several cytokine families have roles in the development, maintenance, and remodeling of the microcirculation. Of these, the vascular endothelial growth factor (VEGF) family is one of the best studied and one of the most complex. Five VEGF ligand genes and five cell-surface receptor genes are known in the human, and each of these may be transcribed as multiple splice isoforms to generate an extensive family of proteins, many of which are subject to further proteolytic processing. Using the VEGF family as an example, we describe the current knowledge of growth-factor expression, processing, and transport in vivo. Experimental studies and computational simulations are being used to measure and predict the activity of these molecules, and we describe avenues of research that seek to fill the remaining gaps in our understanding of VEGF family behavior.
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Affiliation(s)
- Feilim Mac Gabhann
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, USA.
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Long SB, Long MB, White RR, Sullenger BA. Crystal structure of an RNA aptamer bound to thrombin. RNA (NEW YORK, N.Y.) 2008; 14:2504-2512. [PMID: 18971322 PMCID: PMC2590953 DOI: 10.1261/rna.1239308] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 09/11/2008] [Indexed: 05/26/2023]
Abstract
Aptamers, an emerging class of therapeutics, are DNA or RNA molecules that are selected to bind molecular targets that range from small organic compounds to large proteins. All of the determined structures of aptamers in complex with small molecule targets show that aptamers cage such ligands. In structures of aptamers in complex with proteins that naturally bind nucleic acid, the aptamers occupy the nucleic acid binding site and often mimic the natural interactions. Here we present a crystal structure of an RNA aptamer bound to human thrombin, a protein that does not naturally bind nucleic acid, at 1.9 A resolution. The aptamer, which adheres to thrombin at the binding site for heparin, presents an extended molecular surface that is complementary to the protein. Protein recognition involves the stacking of single-stranded adenine bases at the core of the tertiary fold with arginine side chains. These results exemplify how RNA aptamers can fold into intricate conformations that allow them to interact closely with extended surfaces on non-RNA binding proteins.
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Affiliation(s)
- Stephen B Long
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
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17
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Imino proton exchange rates imply an induced-fit binding mechanism for the VEGF165-targeting aptamer, Macugen. FEBS Lett 2008; 582:1835-9. [PMID: 18485899 DOI: 10.1016/j.febslet.2008.05.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2008] [Revised: 04/26/2008] [Accepted: 05/04/2008] [Indexed: 11/21/2022]
Abstract
The 2'-fluoro/2'-O-methyl modified RNA aptamer Macugen is a potent inhibitor of the angiogenic regulatory protein, VEGF165. Macugen binds with high affinity to the heparin-binding domain (HBD) of VEGF165. Hydrogen exchange rates of the imino protons were measured for free Macugen and Macugen bound to the HBD or full-length VEGF to better understand the mechanism for high affinity binding. The results here show that the internal loop and hairpin loop of Macugen are highly dynamic in the free state and are greatly stabilized and/or protected from solvent upon protein binding.
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18
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Improvement of Aptamer Affinity by Dimerization. SENSORS 2008; 8:1090-1098. [PMID: 27879754 PMCID: PMC3927496 DOI: 10.3390/s8021090] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 02/15/2008] [Indexed: 11/17/2022]
Abstract
To increase the affinities of aptamers for their targets, we designed an aptamer dimer for thrombin and VEGF. This design is based on the avidity of the antibody, which enables the aptamer to connect easily since it is a single-strand nucleic acid. In this study, we connected a 15-mer thrombin-binding aptamer with a 29-mer thrombin-binding aptamer. Each aptamer recognizes a different part of the thrombin molecule, and the aptamer dimer has a Kd value which is 1/10 of that of the monomers from which it is composed. Also, the designed aptamer dimer has higher inhibitory activity than the reported (15-mer) thrombin-inhibiting aptamer. Additionally, we connected together two identical aptamers against vascular endothelial growth factor (VEGF165), which is a homodimeric protein. As in the case of the anti-thrombin aptamer, the dimeric anti-VEGF aptamer had a much lower Kd value than that of the monomer. This study demonstrated that the dimerization of aptamers effectively improves the affinities of those aptamers for their targets.
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19
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Starzec A, Ladam P, Vassy R, Badache S, Bouchemal N, Navaza A, du Penhoat CH, Perret GY. Structure-function analysis of the antiangiogenic ATWLPPR peptide inhibiting VEGF(165) binding to neuropilin-1 and molecular dynamics simulations of the ATWLPPR/neuropilin-1 complex. Peptides 2007; 28:2397-402. [PMID: 17983687 DOI: 10.1016/j.peptides.2007.09.013] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 09/11/2007] [Accepted: 09/14/2007] [Indexed: 01/13/2023]
Abstract
Heptapeptide ATWLPPR (A7R), identified in our laboratory by screening a mutated phage library, was shown to bind specifically to neuropilin-1 (NRP-1) and then to selectively inhibit VEGF(165) binding to this receptor. In vivo, treatment with A7R resulted in decreasing breast cancer angiogenesis and growth. The present work is focused on structural characterization of A7R. Analogs of the peptide, obtained by substitution of each amino acid with alanine (alanine-scanning) or by amino acid deletion, have been systematically assayed to determine the relative importance of the side chains of each residue with respect to the inhibitory effect of A7R on VEGF(165) binding to NRP-1. We show here the importance of the C-terminal sequence LPPR and particularly the key role of C-terminal arginine. In solution, A7R displays significant secondary structure of the backbone adopting an extended conformation. However, the functional groups of arginine are very flexible in the absence of NRP-1 pointing to an induced fit upon binding to the receptor. A MD trajectory of the A7R/NRP-1 complex in explicit water, based on the recent tuftsin/NRP-1 crystal structure, has revealed the hydrogen-bonding network that contributes to A7R's binding activity.
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Affiliation(s)
- Anna Starzec
- Université Paris 13, UMR 7033, 74 rue Marcel Cachin, 93017 Bobigny, France
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20
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Krilleke D, DeErkenez A, Schubert W, Giri I, Robinson GS, Ng YS, Shima DT. Molecular mapping and functional characterization of the VEGF164 heparin-binding domain. J Biol Chem 2007; 282:28045-56. [PMID: 17626017 DOI: 10.1074/jbc.m700319200] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The longer splice isoforms of vascular endothelial growth factor-A (VEGF-A), including mouse VEGF164, contain a highly basic heparin-binding domain (HBD), which imparts the ability of these isoforms to be deposited in the heparan sulfate-rich extracellular matrix and to interact with the prototype sulfated glycosaminoglycan, heparin. The shortest isoform, VEGF120, lacks this highly basic domain and is freely diffusible upon secretion. Although the HBD has been attributed significant relevance to VEGF-A biology, the molecular determinants of the heparin-binding site are unknown. We used site-directed mutagenesis to identify amino acid residues that are critical for heparin binding activity of the VEGF164 HBD. We focused on basic residues and found Arg-13, Arg-14, and Arg-49 to be critical for heparin binding and interaction with extracellular matrix in tissue samples. We also examined the cellular and biochemical consequences of abolishing heparin-binding function, measuring the ability of the mutants to interact with VEGF receptors, induce endothelial cell gene expression, and trigger microvessel outgrowth. Induction of tissue factor expression, vessel outgrowth, and binding to VEGFR2 were unaffected by the HBD mutations. In contrast, the HBD mutants showed slightly decreased binding to the NRP1 (neuropilin-1) receptor, and analyses suggested the heparin and NRP1 binding sites to be distinct but overlapping. Finally, mutations that affect the heparin binding activity also led to an unexpected reduction in the affinity of VEGF164 binding specifically to VEGFR1. This finding provides a potential basis for previous observations suggesting enhanced potency of VEGF164 versus VEGF120 in VEGFR1-mediated signaling in inflammatory cells.
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21
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Jia H, Bagherzadeh A, Hartzoulakis B, Jarvis A, Löhr M, Shaikh S, Aqil R, Cheng L, Tickner M, Esposito D, Harris R, Driscoll PC, Selwood DL, Zachary IC. Characterization of a bicyclic peptide neuropilin-1 (NP-1) antagonist (EG3287) reveals importance of vascular endothelial growth factor exon 8 for NP-1 binding and role of NP-1 in KDR signaling. J Biol Chem 2006; 281:13493-13502. [PMID: 16513643 DOI: 10.1074/jbc.m512121200] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuropilin-1 (NP-1) is a receptor for vascular endothelial growth factor-A165 (VEGF-A165) in endothelial cells. To define the role of NP-1 in the biological functions of VEGF, we developed a specific peptide antagonist of VEGF binding to NP-1 based on the NP-1 binding site located in the exon 7- and 8-encoded VEGF-A165 domain. The bicyclic peptide, EG3287, potently (K(i) 1.2 microM) and effectively (>95% inhibition at 100 microM) inhibited VEGF-A165 binding to porcine aortic endothelial cells expressing NP-1 (PAE/NP-1) and breast carcinoma cells expressing only NP-1 receptors for VEGF-A, but had no effect on binding to PAE/KDR or PAE/Flt-1. Molecular dynamics calculations, a nuclear magnetic resonance structure of EG3287, and determination of stability in media, indicated that it constitutes a stable subdomain very similar to the corresponding region of native VEGF-A165. The C terminus encoded by exon 8 and the three-dimensional structure were both critical for EG3287 inhibition of NP-1 binding, whereas modifications at the N terminus had little effect. Although EG3287 had no direct effect on VEGF-A165 binding to KDR receptors, it inhibited cross-linking of VEGF-A165 to KDR in human umbilical vein endothelial cells co-expressing NP-1, and inhibited stimulation of KDR and PLC-gamma tyrosine phosphorylation, activation of ERKs1/2 and prostanoid production. These findings characterize the first specific antagonist of VEGF-A165 binding to NP-1 and demonstrate that NP-1 is essential for optimum KDR activation and intracellular signaling. The results also identify a key role for the C-terminal exon 8 domain in VEGF-A165 binding to NP-1.
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Affiliation(s)
- Haiyan Jia
- Centre for Cardiovascular Biology and Medicine, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom; Ark Therapeutics Limited, The Rayne Institute, University College London, London WC1E 6JJ, United Kingdom
| | - Azadeh Bagherzadeh
- Centre for Cardiovascular Biology and Medicine, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom; Ark Therapeutics Limited, The Rayne Institute, University College London, London WC1E 6JJ, United Kingdom
| | | | - Ashley Jarvis
- NCE Discovery Ltd., Cambridge CB4 0PA, United Kingdom
| | - Marianne Löhr
- Wolfson Institute for Biomedical Research, University College London, London WC1E GBT United Kingdom
| | | | - Rehan Aqil
- NCE Discovery Ltd., Cambridge CB4 0PA, United Kingdom
| | - Lili Cheng
- Centre for Cardiovascular Biology and Medicine, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom; Ark Therapeutics Limited, The Rayne Institute, University College London, London WC1E 6JJ, United Kingdom
| | - Michelle Tickner
- Centre for Cardiovascular Biology and Medicine, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom; Ark Therapeutics Limited, The Rayne Institute, University College London, London WC1E 6JJ, United Kingdom
| | - Diego Esposito
- Bloomsbury Centre for Structure Biology, Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - Richard Harris
- Bloomsbury Centre for Structure Biology, Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - Paul C Driscoll
- Bloomsbury Centre for Structure Biology, Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - David L Selwood
- Wolfson Institute for Biomedical Research, University College London, London WC1E GBT United Kingdom
| | - Ian C Zachary
- Centre for Cardiovascular Biology and Medicine, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom.
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22
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Lee JH, Canny MD, De Erkenez A, Krilleke D, Ng YS, Shima DT, Pardi A, Jucker F. A therapeutic aptamer inhibits angiogenesis by specifically targeting the heparin binding domain of VEGF165. Proc Natl Acad Sci U S A 2005; 102:18902-7. [PMID: 16357200 PMCID: PMC1323181 DOI: 10.1073/pnas.0509069102] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Aptamers recognize their targets with extraordinary affinity and specificity. The aptamer-based therapeutic, Macugen, is derived from a modified 2'fluoro pyrimidine RNA inhibitor to vascular endothelial growth factor (VEGF) and is now being used to treat the wet form of age-related macular degeneration. This VEGF(165) aptamer binds specifically to the VEGF(165) isoform, a dimeric protein with a receptor-binding domain and a heparin-binding domain (HBD). To understand the molecular recognition between VEGF and this aptamer, binding experiments were used to show that the HBD contributes the majority of binding energy in the VEGF(165)-aptamer complex. A tissue culture-based competition assay demonstrated that the HBD effectively competes with VEGF(165) for aptamer binding in vivo. Comparison of NMR spectra revealed that structural features of the smaller HBD-aptamer complex are present in the full-length VEGF(164)-aptamer complex. These data show that the HBD provides the binding site for the aptamer and is the primary determinant for the affinity and specificity in the VEGF(165)-aptamer complex.
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Affiliation(s)
- Joon-Hwa Lee
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
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23
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Crombez M, Chevallier P, -Gaudreault RC, Petitclerc E, Mantovani D, Laroche G. Improving arterial prosthesis neo-endothelialization: application of a proactive VEGF construct onto PTFE surfaces. Biomaterials 2005; 26:7402-9. [PMID: 16005960 DOI: 10.1016/j.biomaterials.2005.05.051] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The formation of a confluent endothelium on expanded polytetrafluoroethylene (PTFE) vascular prostheses has never been observed. This lack of endothelialization is known to be one of the main reasons leading to the development of thromboses and/or intimal hyperplasia. In this context, several efforts were put forward to promote endothelial cell coverage on the internal surface of synthetic vascular prostheses. The goal of the present study was to immobilize the vascular endothelial growth factor (VEGF) onto Teflon PTFE surfaces to generate a proactive polymer construct favoring interaction with endothelial cells. An ammonia plasma treatment was first used to graft amino groups on PTFE films. Subsequent reactions were performed to covalently bind human serum albumin (HSA) on the polymer surface and to load this protein with negative charges, which allows adsorbtion of VEGF onto HSA via strong electrostatic interactions. X-ray photoelectron spectroscopy (XPS) experiments along with surface derivatization strategies were performed between each synthesis step to ascertain the occurrence of the various molecules surface immobilization. Finally, the electrostatic binding of VEGF to the negatively charged HSA matrix was performed and validated by ELISA. Endothelial cell adhesion and migration experiments were carried out to validate the potential of this VEGF-containing biological construct to act as a proactive media toward the development of endothelial cells.
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Affiliation(s)
- M Crombez
- Unité de Biotechnologie et de Bioingénierie, Centre de Recherche de l'Hôpital Saint-François d'Assise, C.H.U.Q., Qué., Canada G1L 3L5
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24
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Jain NU, Tjioe E, Savidor A, Boulie J. Redox-dependent structural differences in putidaredoxin derived from homologous structure refinement via residual dipolar couplings. Biochemistry 2005; 44:9067-78. [PMID: 15966730 DOI: 10.1021/bi050152c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structural differences in the [2Fe-2S] ferredoxin, putidaredoxin (Pdx), from the camphor hydroxylation pathway of Pseudomonas putida have been investigated as a function of oxidation state of the iron cluster. Pdx is involved in biological electron transfer to cytochrome P450(cam) (CYP101). Redox-dependent differences have been observed previously for Pdx in terms of binding affinities to CYP101, NMR spectral differences, and dynamic properties. To further characterize these differences, structure refinement of both oxidized and reduced Pdx has been carried out using a hybrid approach utilizing paramagnetic distance restraints and NMR orientational restraints in the form of backbone (15)N residual dipolar couplings. Use of these new restraints has improved the structure of oxidized Pdx considerably over the earlier solution NMR structure without RDC restraints, with the new structure now much closer in overall fold to the recently published X-ray crystal structures. We now observe better defined relative orientations of the major secondary structure elements as also of the conformation of the metal binding loop region. Extension of this approach to structure calculation of reduced Pdx has identified structural differences that are primarily localized for residues in the C-terminal interaction domain consisting of the functionally important residue Trp 106 and regions near the metal binding loop in Pdx. These redox-dependent structural differences in Pdx correlate to dynamic changes observed before and may be linked to differences in binding and electron transfer properties between oxidized and reduced Pdx.
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Affiliation(s)
- Nitin U Jain
- Biochemistry, Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee 37996-0840, USA.
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25
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García-Mayoral MF, Pantoja-Uceda D, Santoro J, Martínez del Pozo A, Gavilanes JG, Rico M, Bruix M. Refined NMR structure of α-sarcin by 15N–1H residual dipolar couplings. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:1057-65. [PMID: 15812638 DOI: 10.1007/s00249-005-0473-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Accepted: 02/14/2005] [Indexed: 10/25/2022]
Abstract
(15)N-(1)H residual dipolar couplings (RDC) have been used as additional restraints to refine the solution structure of the ribotoxin alpha-sarcin. The RDC values were obtained by partial alignment of alpha-sarcin in the binary mixture of n-dodecyl hexa(ethylene glycol)/hexanol. A total of 131 RDCs were measured and 106 were introduced in the final steps of the calculation protocol following the main calculation based on nuclear Overhauser enhancements and torsion angle restraints. A homogeneous family of 81 conformers was obtained. The resulting average pairwise root-mean-square deviation corresponding to the superposition of the 20 best structures is 0.69+/-0.12 A for the backbone and 1.29+/-0.14 A for all heavy atoms. The new structural features derived from the refined structure, compared with the non-refined structure of alpha-sarcin, consist of new hydrogen bonds and a better definition of the backbone conformation. In particular, the loop segment spanning Gly 60 to Lys 70 shows a single conformation, corresponding to the most populated family of conformers observed in the unrefined structure. The information derived from the analysis of the refined structure and the comparison with the homologous protein restrictocin could help in establishing further structure-function relationships concerning alpha-sarcin which can be reasonably extrapolated to other members of the ribotoxin family.
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Affiliation(s)
- Mâria Flor García-Mayoral
- Departamento de Espectroscopía y Estructura Molecular, Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
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26
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Jain NU, Wyckoff TJO, Raetz CRH, Prestegard JH. Rapid analysis of large protein-protein complexes using NMR-derived orientational constraints: the 95 kDa complex of LpxA with acyl carrier protein. J Mol Biol 2004; 343:1379-89. [PMID: 15491619 DOI: 10.1016/j.jmb.2004.08.103] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 08/31/2004] [Accepted: 08/31/2004] [Indexed: 10/26/2022]
Abstract
Characterization of protein-protein interactions that are critical to the specific function of many biological systems has become a primary goal of structural biology research. Analysis of these interactions by structural techniques is, however, challenging due to inherent limitations of the techniques and because many of the interactions are transient, and suitable complexes are difficult to isolate. In particular, structural studies of large protein complexes by traditional solution NMR methods are difficult due to a priori requirement of extensive assignments and a large number of intermolecular restraints for the complex. An approach overcoming some of these challenges by utilizing orientational restraints from residual dipolar couplings collected on solution NMR samples is presented. The approach exploits existing structures of individual components, including the symmetry properties of some of these structures, to assemble rapidly models for relatively large protein-protein complexes. An application is illustrated with a 95 kDa homotrimeric complex of the acyltransferase protein, LpxA (UDP-N-acetylglucosamine acyltransferase), and acyl carrier protein. LpxA catalyzes the first step in the biosynthesis of the lipid A component of lipopolysaccharide in Gram-negative bacteria. The structural model generated for this complex can be useful in the design of new anti-bacterial agents that inhibit the biosynthesis of lipid A.
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Affiliation(s)
- Nitin U Jain
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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27
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Zheng D, Aramini JM, Montelione GT. Validation of helical tilt angles in the solution NMR structure of the Z domain of Staphylococcal protein A by combined analysis of residual dipolar coupling and NOE data. Protein Sci 2004; 13:549-54. [PMID: 14718654 PMCID: PMC2286702 DOI: 10.1110/ps.03351704] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Staphylococcal protein A (SpA) is a virulence factor from Staphylococcus aureus that is able to bind to immunoglobulins. The 3D structures of its immunoglobulin (Ig) binding domains have been extensively studied by NMR and X-ray crystallography, and are often used as model structures in developing de novo or ab initio strategies for predicting protein structure. These small three-helix-bundle structures, reported in free proteins or Ig-bound complexes, have been determined previously using medium- to high-resolution data. Although the location and relative orientation of the three helices in most of these published 3D domain structures are consistent, there are significant differences among the reported structures regarding the tilt angle of the first helix (helix 1). We have applied residual dipolar coupling data, together with nuclear Overhauser enhancement and scalar coupling data, in refining the NMR solution structure of an engineered IgG-binding domain (Z domain) of SpA. Our results demonstrate that the three helices are almost perfectly antiparallel in orientation, with the first helix tilting slightly away from the other two helices. We propose that this high-accuracy structure of the Z domain of SpA is a more suitable target for theoretical predictions of the free domain structure than previously published lower-accuracy structures of protein A domains.
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Affiliation(s)
- Deyou Zheng
- CABM-Rutgers University, 679 Hoes Lane, Piscataway, NJ 08854, USA
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