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Schuurs ZP, Hammond E, Elli S, Rudd TR, Mycroft-West CJ, Lima MA, Skidmore MA, Karlsson R, Chen YH, Bagdonaite I, Yang Z, Ahmed YA, Richard DJ, Turnbull J, Ferro V, Coombe DR, Gandhi NS. Evidence of a putative glycosaminoglycan binding site on the glycosylated SARS-CoV-2 spike protein N-terminal domain. Comput Struct Biotechnol J 2021; 19:2806-2818. [PMID: 33968333 PMCID: PMC8093007 DOI: 10.1016/j.csbj.2021.05.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/01/2021] [Accepted: 05/01/2021] [Indexed: 12/14/2022] Open
Abstract
SARS-CoV-2 has rapidly spread throughout the world's population since its initial discovery in 2019. The virus infects cells via a glycosylated spike protein located on its surface. The protein primarily binds to the angiotensin-converting enzyme-2 (ACE2) receptor, using glycosaminoglycans (GAGs) as co-receptors. Here, we performed bioinformatics and molecular dynamics simulations of the spike protein to investigate the existence of additional GAG binding sites on the receptor-binding domain (RBD), separate from previously reported heparin-binding sites. A putative GAG binding site in the N-terminal domain (NTD) of the protein was identified, encompassing residues 245-246. We hypothesized that GAGs of a sufficient length might bridge the gap between this site and the PRRARS furin cleavage site, including the mutation S247R. Docking studies using GlycoTorch Vina and subsequent MD simulations of the spike trimer in the presence of dodecasaccharides of the GAGs heparin and heparan sulfate supported this possibility. The heparan sulfate chain bridged the gap, binding the furin cleavage site and S247R. In contrast, the heparin chain bound the furin cleavage site and surrounding glycosylation structures, but not S247R. These findings identify a site in the spike protein that favors heparan sulfate binding that may be particularly pertinent for a better understanding of the recent UK and South African strains. This will also assist in future targeted therapy programs that could include repurposing clinical heparan sulfate mimetics.
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Affiliation(s)
- Zachariah P. Schuurs
- QUT, Centre for Genomics and Personalised Health, Cancer and Ageing Research Program, School of Chemistry and Physics, Faculty of Science and Engineering, Institute of Health and Biomedical Innovation, 2 George Street, Brisbane, QLD 4000, Australia
| | - Edward Hammond
- Zucero Therapeutics Ltd, 1 Westlink Court, Brisbane, Queensland, Australia
| | - Stefano Elli
- Istituto di Ricerche Chimiche e Biochimiche “G.Ronzoni”, via Giuseppe Colombo 81, 20133 Milano, Italy
| | - Timothy R. Rudd
- National Institute for Biological Standards and Control, Analytical and Biological Sciences Division, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK
| | - Courtney J. Mycroft-West
- Molecular & Structural Biosciences, School of Life Sciences, Keele University, Newcastle-Under-Lyme, Staffordshire ST5 5BG, UK
| | - Marcelo A. Lima
- Molecular & Structural Biosciences, School of Life Sciences, Keele University, Newcastle-Under-Lyme, Staffordshire ST5 5BG, UK
| | - Mark A. Skidmore
- Molecular & Structural Biosciences, School of Life Sciences, Keele University, Newcastle-Under-Lyme, Staffordshire ST5 5BG, UK
| | - Richard Karlsson
- Copenhagen Center for Glycomics, Department of Cellular & Molecular Medicine, University of Copenhagen, Copenhagen N 2200, Denmark
| | - Yen-Hsi Chen
- Copenhagen Center for Glycomics, Department of Cellular & Molecular Medicine, University of Copenhagen, Copenhagen N 2200, Denmark
| | - Ieva Bagdonaite
- Copenhagen Center for Glycomics, Department of Cellular & Molecular Medicine, University of Copenhagen, Copenhagen N 2200, Denmark
| | - Zhang Yang
- Copenhagen Center for Glycomics, Department of Cellular & Molecular Medicine, University of Copenhagen, Copenhagen N 2200, Denmark
| | - Yassir A. Ahmed
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Derek J. Richard
- QUT, Centre for Genomics and Personalised Health, Cancer & Ageing Research Program, Institute of Health and Biomedical Innovation at the Translational Research Institute (TRI), 37 Kent Street, Woolloongabba, Queensland 4102, Australia
| | - Jeremy Turnbull
- Copenhagen Center for Glycomics, Department of Cellular & Molecular Medicine, University of Copenhagen, Copenhagen N 2200, Denmark
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Vito Ferro
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Deirdre R. Coombe
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Neha S. Gandhi
- QUT, Centre for Genomics and Personalised Health, Cancer and Ageing Research Program, School of Chemistry and Physics, Faculty of Science and Engineering, Institute of Health and Biomedical Innovation, 2 George Street, Brisbane, QLD 4000, Australia
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Zubkova OV, Ahmed YA, Guimond SE, Noble SL, Miller JH, Alfred Smith RA, Nurcombe V, Tyler PC, Weissmann M, Vlodavsky I, Turnbull JE. Dendrimer Heparan Sulfate Glycomimetics: Potent Heparanase Inhibitors for Anticancer Therapy. ACS Chem Biol 2018; 13:3236-3242. [PMID: 30480427 DOI: 10.1021/acschembio.8b00909] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Heparanase is a mammalian endoglycosidase that cleaves heparan sulfate (HS) polysaccharides and contributes to remodelling of the extracellular matrix and regulation of HS-binding protein bioavailabilities. Heparanase is upregulated in malignant cancers and inflammation, aiding cell migration and the release of signaling molecules. It is established as a highly druggable extracellular target for anticancer therapy, but current compounds have limitations, because of cost, production complexity, or off-target effects. Here, we report the synthesis of a novel, targeted library of single-entity glycomimetic clusters capped with simple sulfated saccharides. Several dendrimer HS glycomimetics display low nM IC50 potency for heparanase inhibition equivalent to comparator compounds in clinical development, and potently inhibit metastasis and growth of human myeloma tumor cells in a mouse xenograft model. Importantly, they lack anticoagulant activity and cytotoxicity, and also inhibit angiogenesis. They provide a new candidate class for anticancer and wider therapeutic applications, which could benefit from targeted heparanase inhibition.
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Affiliation(s)
- Olga V. Zubkova
- The Ferrier Research Institute, Victoria University of Wellington, Gracefield Research Centre, Lower Hutt, New Zealand
| | - Yassir A. Ahmed
- Dept. of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Scott E. Guimond
- Dept. of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Sophia-Louise Noble
- School of Biological Sciences, Victoria University of Wellington, Kelburn, Wellington, New Zealand
| | - John Holmes Miller
- School of Biological Sciences, Victoria University of Wellington, Kelburn, Wellington, New Zealand
| | - Raymond Alexander Alfred Smith
- Glycotherapeutics Group (VNSC), Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), 138632 Singapore
| | - Victor Nurcombe
- Glycotherapeutics Group (VNSC), Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), 138632 Singapore
| | - Peter C. Tyler
- The Ferrier Research Institute, Victoria University of Wellington, Gracefield Research Centre, Lower Hutt, New Zealand
| | - Marina Weissmann
- Cancer and Vascular Biology Research Center, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Israel Vlodavsky
- Cancer and Vascular Biology Research Center, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Jeremy E. Turnbull
- Dept. of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
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Gray CJ, Sánchez-Ruíz A, Šardzíková I, Ahmed YA, Miller RL, Reyes Martinez JE, Pallister E, Huang K, Both P, Hartmann M, Roberts HN, Šardzík R, Mandal S, Turnbull JE, Eyers CE, Flitsch SL. Label-Free Discovery Array Platform for the Characterization of Glycan Binding Proteins and Glycoproteins. Anal Chem 2017; 89:4444-4451. [PMID: 28318230 DOI: 10.1021/acs.analchem.6b04122] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The identification of carbohydrate-protein interactions is central to our understanding of the roles of cell-surface carbohydrates (the glycocalyx), fundamental for cell-recognition events. Therefore, there is a need for fast high-throughput biochemical tools to capture the complexity of these biological interactions. Here, we describe a rapid method for qualitative label-free detection of carbohydrate-protein interactions on arrays of simple synthetic glycans, more complex natural glycosaminoglycans (GAG), and lectins/carbohydrate binding proteins using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The platform can unequivocally identify proteins that are captured from either purified or complex sample mixtures, including biofluids. Identification of proteins bound to the functionalized array is achieved by analyzing either the intact protein mass or, after on-chip proteolytic digestion, the peptide mass fingerprint and/or tandem mass spectrometry of selected peptides, which can yield highly diagnostic sequence information. The platform described here should be a valuable addition to the limited analytical toolbox that is currently available for glycomics.
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Affiliation(s)
- Christopher J Gray
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Antonio Sánchez-Ruíz
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Ivana Šardzíková
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Yassir A Ahmed
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Rebecca L Miller
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Juana E Reyes Martinez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato , Col. Noria Alta S/N, Guanajuato 36050, México
| | - Edward Pallister
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Kun Huang
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Peter Both
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Mirja Hartmann
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Hannah N Roberts
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Robert Šardzík
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Santanu Mandal
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Jerry E Turnbull
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Claire E Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Sabine L Flitsch
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester , 131 Princess Street, Manchester, M1 7DN, United Kingdom
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Ahmed YA, Yates EA, Moss DJ, Loeven MA, Hussain SA, Hohenester E, Turnbull JE, Powell AK. Panels of chemically-modified heparin polysaccharides and natural heparan sulfate saccharides both exhibit differences in binding to Slit and Robo, as well as variation between protein binding and cellular activity. Mol Biosyst 2016; 12:3166-75. [PMID: 27502551 PMCID: PMC5048398 DOI: 10.1039/c6mb00432f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/04/2016] [Indexed: 01/09/2023]
Abstract
Heparin/heparan sulfate (HS) glycosaminoglycans are required for Slit-Robo cellular responses. Evidence exists for interactions between each combination of Slit, Robo and heparin/HS and for formation of a ternary complex. Heparin/HS are complex mixtures displaying extensive structural diversity. The relevance of this diversity has been studied to a limited extent using a few select chemically-modified heparins as models of HS diversity. Here we extend these studies by parallel screening of structurally diverse panels of eight chemically-modified heparin polysaccharides and numerous natural HS oligosaccharide chromatographic fractions for binding to both Drosophila Slit and Robo N-terminal domains and for activation of a chick retina axon response to the Slit fragment. Both the polysaccharides and oligosaccharide fractions displayed variability in binding and cellular activity that could not be attributed solely to increasing sulfation, extending evidence for the importance of structural diversity to natural HS as well as model modified heparins. They also displayed differences in their interactions with Slit compared to Robo, with Robo preferring compounds with higher sulfation. Furthermore, the patterns of cellular activity across compounds were different to those for binding to each protein, suggesting that biological outcomes are selectively determined in a subtle manner that does not simply reflect the sum of the separate interactions of heparin/HS with Slit and Robo.
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Affiliation(s)
- Yassir A. Ahmed
- Centre for Glycobiology , Institute of Integrative Biology , University of Liverpool , UK
- Department of Chemistry , Faculty of Science , King Faisal University , Kingdom of Saudi Arabia
| | - Edwin A. Yates
- Centre for Glycobiology , Institute of Integrative Biology , University of Liverpool , UK
| | - Diana J. Moss
- Department of Cellular and Molecular Physiology , University of Liverpool , UK
| | - Markus A. Loeven
- Centre for Glycobiology , Institute of Integrative Biology , University of Liverpool , UK
| | | | | | - Jeremy E. Turnbull
- Centre for Glycobiology , Institute of Integrative Biology , University of Liverpool , UK
| | - Andrew K. Powell
- Centre for Glycobiology , Institute of Integrative Biology , University of Liverpool , UK
- School of Pharmacy and Biomolecular Sciences , Liverpool John Moores University , Liverpool , UK .
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5
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Uniewicz KA, Ori A, Ahmed YA, Yates EA, Fernig DG. Characterisation of the interaction of neuropilin-1 with heparin and a heparan sulfate mimetic library of heparin-derived sugars. PeerJ 2014; 2:e461. [PMID: 25024924 PMCID: PMC4089425 DOI: 10.7717/peerj.461] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/09/2014] [Indexed: 12/22/2022] Open
Abstract
Background. Neuropilin-1 (NRP-1) is a multidomain membrane protein with soluble isoforms interacting with a complex network of other membrane receptors, their respective ligands and heparan sulfate (HS). It is involved in the development of vasculature, neural patterning, immunological responses and pathological angiogenesis. Methods. We have characterised the binding of a Fc fusion of rat NRP-1 (Fc rNRP-1) and of a soluble isoform, corresponding to the first four extracellular domains of human NRP-1, shNRP-1, using optical biosensor-based binding assays with a library of heparin derivatives. Selective labelling of lysines protected upon heparin binding allowed their identification by mass spectrometry. Results. Fc rNRP-1 bound to heparin with high affinity (2.5 nM) and fast ka (9.8 × 10(6) M(-1)s(-1)). Unusually, NRP-1 bound both highly sulfated and completely desulfated stretches of heparin and exhibited a complex pattern of preferences for chemically modified heparins possessing one or two sulfate groups, e.g., it bound heparin with just a 6-O sulfate group better than heparin with any two of N-sulfate, 6-O sulfate and 2-O sulfate. Mass-spectrometry based mapping identified that, in addition to the expected the b1 domain, the a1, and c domains and the L2 linker were also involved in the interaction. In contrast, shNRP-1 bound heparin far more weakly. This could only be shown by affinity chromatography and by differential scanning fluorimetry. Discussion. The results suggest that the interaction of NRP-1 with HS is more complex than anticipated and involving a far greater extent of the protein than just the b1-b2 domains. NRP-1's preference for binding long saccharide structures suggests it has the potential to bind large segments of HS chains and so organise their local structure. In contrast, the four domain soluble isoform, shNRP-1 binds heparin weakly and so would be expected to diffuse away rapidly from the source cell.
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Affiliation(s)
- Katarzyna A Uniewicz
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Liverpool , United Kingdom
| | - Alessandro Ori
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Liverpool , United Kingdom
| | - Yassir A Ahmed
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Liverpool , United Kingdom
| | - Edwin A Yates
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Liverpool , United Kingdom
| | - David G Fernig
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool , Liverpool , United Kingdom
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Matthews LR, Danner OK, Ahmed YA, Dennis-Griggs DM, Frederick A, Clark C, Moore R, DuMornay W, Childs EW, Wilson KL. Combination therapy with vitamin D3, progesterone, omega-3 fatty acids and glutamine reverses coma and improves clinical outcomes in patients with severe traumatic brain injuries: A case series. ACTA ACUST UNITED AC 2013. [DOI: 10.5348/ijcri-2013-03-281-cs-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Xu R, Ori A, Rudd TR, Uniewicz KA, Ahmed YA, Guimond SE, Skidmore MA, Siligardi G, Yates EA, Fernig DG. Diversification of the structural determinants of fibroblast growth factor-heparin interactions: implications for binding specificity. J Biol Chem 2012; 287:40061-73. [PMID: 23019343 DOI: 10.1074/jbc.m112.398826] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The functions of a large number (>435) of extracellular regulatory proteins are controlled by their interactions with heparan sulfate (HS). In the case of fibroblast growth factors (FGFs), HS binding determines their transport between cells and is required for the assembly of high affinity signaling complexes with their cognate FGF receptor. However, the specificity of the interaction of FGFs with HS is still debated. Here, we use a panel of FGFs (FGF-1, FGF-2, FGF-7, FGF-9, FGF-18, and FGF-21) spanning five FGF subfamilies to probe their specificities for HS at different levels as follows: binding parameters, identification of heparin-binding sites (HBSs) in the FGFs, changes in their secondary structure caused by heparin binding and structures in the sugar required for binding. For interaction with heparin, the FGFs exhibit K(D) values varying between 38 nM (FGF-18) and 620 nM (FGF-9) and association rate constants spanning over 20-fold (FGF-1, 2,900,000 M(-1) s(-1) and FGF-9, 130,000 M(-1) s(-1)). The canonical HBS in FGF-1, FGF-2, FGF-7, FGF-9, and FGF-18 differs in its size, and these FGFs have a different complement of secondary HBS, ranging from none (FGF-9) to two (FGF-1). Differential scanning fluorimetry identified clear preferences in these FGFs for distinct structural features in the polysaccharide. These data suggest that the differences in heparin-binding sites in both the protein and the sugar are greatest between subfamilies and may be more restricted within a FGF subfamily in accord with the known conservation of function within FGF subfamilies.
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Affiliation(s)
- Ruoyan Xu
- Institute of Integrative Biology, Department of Chemical and Structural Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom
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Puvirajesinghe TM, Ahmed YA, Powell AK, Fernig DG, Guimond SE, Turnbull JE. Array-based functional screening of heparin glycans. ACTA ACUST UNITED AC 2012; 19:553-8. [PMID: 22633407 DOI: 10.1016/j.chembiol.2012.03.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 03/16/2012] [Accepted: 03/19/2012] [Indexed: 11/18/2022]
Abstract
Array methodologies have become powerful tools for interrogation of glycan-protein interactions but have critically lacked the ability to generate cell response data. Here, we report the development of a slide-based array method exemplified by measurement of activation of fibroblast growth factor signaling by heparin saccharides. Heparan sulfate-deficient Swiss 3T3 cells were overlaid onto an aminosilane-coated slide surface onto which heparin saccharides had been spotted and immobilized. The cells were transiently stimulated with FGF2 and immunofluorescence measured to assess downstream ERK1/2 phosphorylation. Activation of this signaling pathway response was restricted to cells exposed to heparin saccharides competent to activate FGF2 signaling. Differential activation of the overlaid cells by different-sized heparin saccharides was demonstrated by quantitative measurement of fluorescence intensity. This "glycobioarray" platform has significant potential as a generic tool for functional glycomics screening.
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Affiliation(s)
- Tania M Puvirajesinghe
- Centre for Glycobiology, Department of Biochemistry and Cell Biology, Institute of Integrative Biology, The University of Liverpool, Liverpool L69 7ZB, UK
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9
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Abstract
REASON FOR PERFORMING STUDY Equine osteochondrosis results from a failure of endochondral ossification during skeletal growth. Endochondral ossification involves chondrocyte proliferation, hypertrophy and death. Until recently no culture system was available to study these processes in equine chondrocytes. OBJECTIVE To optimise an in vitro model in which equine chondrocytes can be induced to undergo hypertrophy and physiological death as seen in vivo. METHODS Chondrocytes isolated from fetal or older (neonatal, growing and mature) horses were cultured as pellets in 10% fetal calf serum (FCS) or 10% horse serum (HS). The pellets were examined by light and electron microscopy. Total RNA was extracted from the pellets, and quantitative PCR carried out to investigate changes in expression of a number of genes regulating endochondral ossification. RESULTS Chondrocytes from fetal foals, grown as pellets, underwent hypertrophy and died by a process morphologically similar to that seen in vivo. Chondrocytes from horses age >5 months did not undergo hypertrophy in pellet culture. They formed intramembranous inclusion bodies and the cultures included cells of osteoblastic appearance. Pellets from neonatal foals cultured in FCS resembled pellets from older horses, however pellets grown in HS underwent hypertrophy but contained inclusion bodies. Chondrocytes from fetal foals formed a typical cartilage-like tissue grossly and histologically, and expressed the cartilage markers collagen type II and aggrecan mRNA. Expression of Sox9, collagen type II, Runx2, matrix metalloproteinase-13 and connective tissue growth factor mRNA increased at different times in culture. Expression of fibroblast growth factor receptor-3 and vascular endothelial growth factor mRNA decreased with time in culture. CONCLUSIONS Freshly isolated cells from fetal growth cartilage cultured as pellets provide optimal conditions for studying hypertrophy and death of equine chondrocytes. POTENTIAL RELEVANCE This culture system should greatly assist laboratory studies aimed at elucidating the pathogenesis of osteochondrosis.
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Affiliation(s)
- Y A Ahmed
- School of Veterinary Science, University of Melbourne, Parkville, Victoria 3010, Australia
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Mackie EJ, Ahmed YA, Tatarczuch L, Chen KS, Mirams M. Endochondral ossification: how cartilage is converted into bone in the developing skeleton. Int J Biochem Cell Biol 2007; 40:46-62. [PMID: 17659995 DOI: 10.1016/j.biocel.2007.06.009] [Citation(s) in RCA: 619] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 06/05/2007] [Accepted: 06/08/2007] [Indexed: 12/23/2022]
Abstract
Endochondral ossification is the process by which the embryonic cartilaginous model of most bones contributes to longitudinal growth and is gradually replaced by bone. During endochondral ossification, chondrocytes proliferate, undergo hypertrophy and die; the cartilage extracellular matrix they construct is then invaded by blood vessels, osteoclasts, bone marrow cells and osteoblasts, the last of which deposit bone on remnants of cartilage matrix. The sequential changes in chondrocyte behaviour are tightly regulated by both systemic factors and locally secreted factors, which act on receptors to effect intracellular signalling and activation of chondrocyte-selective transcription factors. Systemic factors that regulate the behaviour of chondrocytes in growth cartilage include growth hormone and thyroid hormone, and the local secreted factors include Indian hedgehog, parathyroid hormone-related peptide, fibroblast growth factors and components of the cartilage extracellular matrix. Transcription factors that play critical roles in regulation of chondrocyte gene expression under the control of these extracellular factors include Runx2, Sox9 and MEF2C. The invasion of cartilage matrix by the ossification front is dependent on its resorption by members of the matrix metalloproteinase family, as well as the presence of blood vessels and bone-resorbing osteoclasts. This review, which places an emphasis on recent advances and current areas of debate, discusses the complex interactions between cell types and signalling pathways that govern endochondral ossification.
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Affiliation(s)
- E J Mackie
- School of Veterinary Science, University of Melbourne, Parkville, Victoria 3010, Australia.
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11
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Ahmed YA, Tatarczuch L, Pagel CN, Davies HMS, Mirams M, Mackie EJ. Physiological death of hypertrophic chondrocytes. Osteoarthritis Cartilage 2007; 15:575-86. [PMID: 17174118 DOI: 10.1016/j.joca.2006.10.016] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Accepted: 10/29/2006] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Post-proliferative chondrocytes in growth cartilage are present in two forms, light and dark cells. These cells undergo hypertrophy and die by a mechanism that is morphologically distinct from apoptosis, but has not been characterized. The aims of the current study were to document the ultrastructural appearance of dying hypertrophic chondrocytes, and to establish a culture system in which the mechanism of their death can be examined. DESIGN Growth cartilage from fetal and growing postnatal horses was examined by electron microscopy. Chondrocytes were isolated from epiphyseal cartilage from fetal horses and grown in pellet culture, then examined by light and electron microscopy, and quantitative polymerase chain reaction. RESULTS In tissue specimens, it was observed that dying dark chondrocytes underwent progressive extrusion of cytoplasm into the extracellular space, whereas light chondrocytes appeared to disintegrate within the cellular membrane. Pellets cultured in 0.1% fetal calf serum (FCS) contained dying light and dark chondrocytes similar to those seen in vivo. Transforming growth factor-beta1 or 10% FCS increased the proportion of dark cells and induced cell death. Triiodothyronine increased the differentiation of dark and light cells and induced their death. Dark cells were associated with higher levels of matrix metalloproteinase-13 expression than light cells, and light cells were associated with higher levels of type II collagen expression. CONCLUSIONS Light and dark hypertrophic chondrocytes each undergo a distinctive series of non-apoptotic morphological changes as they die. Pellet culture can be used as a model of the two forms of physiological death of hypertrophic chondrocytes.
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Affiliation(s)
- Y A Ahmed
- School of Veterinary Science, University of Melbourne, Parkville, Victoria 3010, Australia
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13
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Abstract
Eighteen women with hepatic cirrhosis were examined for plasma levels of testosterone, estrone, estradiol, progesterone and sex hormone binding globulin. For eight who were amenorrheic, with advanced liver cirrhosis and ascites, the reduction of testosterone and rise in estrone and sex hormone binding globulin concentrations were significant. Plasma extradiol and progesterone were lower than normal levels, but the differences were not statistically significant. The other ten patients were menstruating (mostly irregularly), and their hormonal levels were assessed in different states of their cycles. All of them did not ovulate, had low levels of plasma progesterone and also showed consistent estrone concentration excess relative to estradiol and significant lowering of testosterone and elevation of sex hormone binding globulin. These findings are compared with previous reports on males with liver cirrhosis.
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