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Garofalo M, Bellato F, Magliocca S, Malfanti A, Kuryk L, Rinner B, Negro S, Salmaso S, Caliceti P, Mastrotto F. Polymer Coated Oncolytic Adenovirus to Selectively Target Hepatocellular Carcinoma Cells. Pharmaceutics 2021; 13:pharmaceutics13070949. [PMID: 34202714 PMCID: PMC8309094 DOI: 10.3390/pharmaceutics13070949] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/08/2021] [Accepted: 06/18/2021] [Indexed: 01/15/2023] Open
Abstract
Despite significant advances in chemotherapy, the overall prognosis of hepatocellular carcinoma (HCC) remains extremely poor. HCC targeting strategies were combined with the tumor cell cytotoxicity of oncolytic viruses (OVs) to develop a more efficient and selective therapeutic system. OVs were coated with a polygalactosyl-b-agmatyl diblock copolymer (Gal32-b-Agm29), with high affinity for the asialoglycoprotein receptor (ASGPR) expressed on the liver cell surface, exploiting the electrostatic interaction of the positively charged agmatine block with the negatively charged adenoviral capsid surface. The polymer coating altered the viral particle diameter (from 192 to 287 nm) and zeta-potential (from -24.7 to 23.3 mV) while hiding the peculiar icosahedral symmetrical OV structure, as observed by TEM. Coated OVs showed high potential therapeutic value on the human hepatoma cell line HepG2 (cytotoxicity of 72.4% ± 4.96), expressing a high level of ASGPRs, while a lower effect was attained with ASPGR-negative A549 cell line (cytotoxicity of 54.4% ± 1.59). Conversely, naked OVs showed very similar effects in both tested cell lines. Gal32-b-Agm29 OV coating enhanced the infectivity and immunogenic cell death program in HepG2 cells as compared to the naked OV. This strategy provides a rationale for future studies utilizing oncolytic viruses complexed with polymers toward effective treatment of hepatocellular carcinoma.
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Affiliation(s)
- Mariangela Garofalo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (F.B.); (S.M.); (S.S.); (P.C.)
- Correspondence: (M.G.); (F.M.); Tel.: +39-04-9827-5710 (M.G.); +39-04-9827-5708 (F.M.)
| | - Federica Bellato
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (F.B.); (S.M.); (S.S.); (P.C.)
| | - Salvatore Magliocca
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (F.B.); (S.M.); (S.S.); (P.C.)
| | - Alessio Malfanti
- Université Catholique de Louvain, Louvain Drug Research Institute, Advanced Drug Delivery and Biomaterials, Avenue Mounier, 73 bte B1 73.12, 1200 Brussels, Belgium;
| | - Lukasz Kuryk
- Department of Virology, National Institute of Public Health—National Institute of Hygiene, Chocimska 24, 00-791 Warsaw, Poland;
- Clinical Science, Targovax Oy, Saukonpaadenranta 2, 00180 Helsinki, Finland
| | - Beate Rinner
- Division of Biomedical Research, Medical University of Graz, Roseggerweg 48, 8036 Graz, Austria;
| | - Samuele Negro
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy;
| | - Stefano Salmaso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (F.B.); (S.M.); (S.S.); (P.C.)
| | - Paolo Caliceti
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (F.B.); (S.M.); (S.S.); (P.C.)
| | - Francesca Mastrotto
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (F.B.); (S.M.); (S.S.); (P.C.)
- Correspondence: (M.G.); (F.M.); Tel.: +39-04-9827-5710 (M.G.); +39-04-9827-5708 (F.M.)
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Taylor ME, Drickamer K. Mammalian sugar-binding receptors: known functions and unexplored roles. FEBS J 2019; 286:1800-1814. [PMID: 30657247 PMCID: PMC6563452 DOI: 10.1111/febs.14759] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 12/11/2018] [Accepted: 01/15/2019] [Indexed: 12/13/2022]
Abstract
Mammalian glycan-binding receptors, sometimes known as lectins, interact with glycans, the oligosaccharide portions of endogenous mammalian glycoproteins and glycolipids as well as sugars on the surfaces of microbes. These receptors guide glycoproteins out of and back into cells, facilitate communication between cells through both adhesion and signaling, and allow the innate immune system to respond quickly to viral, fungal, bacterial, and parasitic pathogens. For many of the roughly 100 glycan-binding receptors that are known in humans, there are good descriptions of what types of glycans they bind and how selectivity for these ligands is achieved at the molecular level. In some cases, there is also comprehensive evidence for the roles that the receptors play at the cellular and organismal levels. In addition to highlighting these well-understood paradigms for glycan-binding receptors, this review will suggest where gaps remain in our understanding of the physiological functions that they can serve.
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Kim JW, Budzak J, Liu Y, Jégouzo SAF, Drickamer K, Taylor ME. Identification of serum glycoprotein ligands for the immunomodulatory receptor blood dendritic cell antigen 2. Glycobiology 2018; 28:592-600. [PMID: 29796630 PMCID: PMC6054153 DOI: 10.1093/glycob/cwy050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/04/2018] [Accepted: 05/19/2018] [Indexed: 12/26/2022] Open
Abstract
Blood dendritic cell antigen 2 (BDCA-2) is a C-type lectin found on the surface of plasmacytoid dendritic cells. It functions as a glycan-binding receptor that downregulates the production of type I interferons and thus plays a role in oligosaccharide-mediated immunomodulation. The carbohydrate recognition domain in BDCA-2 binds selectively to galactose-terminated bi-antennary glycans. Because the plasmacytoid dendritic cells function in a plasma environment rich in glycoproteins, experiments have been undertaken to identify endogenous ligands for blood dendritic cell antigen 2. A combination of blotting, affinity chromatography and proteomic analysis reveals that serum glycoprotein ligands for BDCA-2 include IgG, IgA and IgM. Compared to binding of IgG, which was previously described, IgA and IgM bind with higher affinity. The association constants for the different subclasses of immunoglobulins are below and roughly proportional to the serum concentrations of these glycoprotein ligands. Binding to the other main serum glycoprotein ligand, α2-macroglobulin, is independent of whether this protease inhibitor is activated. Binding to all of these glycoprotein ligands is mediated predominantly by bi-antennary glycans in which each branch bears a terminal galactose residue. The different affinities of the glycoprotein ligands reflect the different numbers of these galactose-terminated glycans and their degree of exposure on the native glycoproteins. The results suggest that normal serum levels of immunoglobulins could downmodulate interferon stimulation of further antibody production.
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Affiliation(s)
- Jong-Won Kim
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College, London, UK
| | - James Budzak
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College, London, UK
| | - Yu Liu
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College, London, UK
| | - Sabine A F Jégouzo
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College, London, UK
| | - Kurt Drickamer
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College, London, UK
| | - Maureen E Taylor
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College, London, UK
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Bon C, Hofer T, Bousquet-Mélou A, Davies MR, Krippendorff BF. Capacity limits of asialoglycoprotein receptor-mediated liver targeting. MAbs 2017; 9:1360-1369. [PMID: 28876162 DOI: 10.1080/19420862.2017.1373924] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The abundant cell surface asialoglycoprotein receptor (ASGPR) is a highly selective receptor found on hepatocytes that potentially can be exploited as a selective shuttle for delivery. Various nucleic acid therapeutics that bind ASGPR are already in clinical development, but this receptor-mediated delivery mechanism can be saturated, which will likely result in reduced selectivity for the liver and therefore increase the likelihood for systemic adverse effects. Therefore, when aiming to utilize this mechanism, it is important to optimize both the administration protocol and the molecular properties. We here present a study using a novel ASGPR-targeted antibody to estimate ASGPR expression, turnover and internalization rates in vivo in mice. Using pharmacokinetic data (intravenous and subcutaneous dosing) and an in-silico target-mediated drug disposition (TMDD) model, we estimate an ASGPR expression level of 1.8 million molecules per hepatocyte. The half-life of the degradation of the receptor was found to be equal to 15 hours and the formed ligand-receptor complex is internalized with a half-life of 5 days. A biodistribution study was performed and confirmed the accuracy of the TMDD model predictions. The kinetics of the ASGPR shows that saturation of the shuttle at therapeutic concentrations is possible; however, simulation allows the dosing schedule to be optimized. The developed TMDD model can be used to support the development of therapies that use the ASGPR as a shuttle into hepatocytes.
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Affiliation(s)
- Charlotte Bon
- a Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel , Basel , Switzerland.,b Ecole Nationale Vétérinaire de Toulouse, Institut National de la Recherche Agronomique, TOXALIM , Université de Toulouse , Toulouse , France
| | - Thomas Hofer
- c Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich , Zurich , Switzerland
| | - Alain Bousquet-Mélou
- b Ecole Nationale Vétérinaire de Toulouse, Institut National de la Recherche Agronomique, TOXALIM , Université de Toulouse , Toulouse , France
| | | | - Ben-Fillippo Krippendorff
- a Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel , Basel , Switzerland
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Tsui P, Higazi DR, Wu Y, Dunmore R, Solier E, Kasali T, Bond NJ, Huntington C, Carruthers A, Hood J, Borrok MJ, Barnes A, Rickert K, Phipps S, Shirinian L, Zhu J, Bowen MA, Dall'Acqua W, Murray LA. The TGF-β inhibitory activity of antibody 37E1B5 depends on its H-CDR2 glycan. MAbs 2016; 9:104-113. [PMID: 27834568 DOI: 10.1080/19420862.2016.1255390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Excessive transforming growth factor (TGF)-β is associated with pro-fibrotic responses in lung disease, yet it also plays essential roles in tissue homeostasis and autoimmunity. Therefore, selective inhibition of excessive and aberrant integrin-mediated TGF-β activation via targeting the α-v family of integrins is being pursued as a therapeutic strategy for chronic lung diseases, to mitigate any potential safety concerns with global TGF-β inhibition. In this work, we reveal a novel mechanism of inhibiting TGF-β activation utilized by an αvβ8 targeting antibody, 37E1B5. This antibody blocks TGF-β activation while not inhibiting cell adhesion. We show that an N-linked complex-type Fab glycan in H-CDR2 of 37E1B5 is directly involved in the inhibition of latent TGF-β activation. Removal of the Fab N-glycosylation site by single amino acid substitution, or removal of N-linked glycans by enzymatic digestion, drastically reduced the antibody's ability to inhibit latency-associated peptide (LAP) and αvβ8 association, and TGF-β activation in an αvβ8-mediated TGF-β signaling reporter assay. Our results indicate a non-competitive, allosteric inhibition of 37E1B5 on αvβ8-mediated TGF-β activation. This unique, H-CDR2 glycan-mediated mechanism may account for the potent but tolerable TGF-b activation inhibition and lack of an effect on cellular adhesion by the antibody.
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Affiliation(s)
- Ping Tsui
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Daniel R Higazi
- b Biopharmaceutical Development, MedImmune Ltd , Cambridge , UK
| | - Yanli Wu
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Rebecca Dunmore
- c Respiratory, Inflammation and Autoimmunity, MedImmune Ltd , Cambridge , UK
| | - Emilie Solier
- b Biopharmaceutical Development, MedImmune Ltd , Cambridge , UK
| | - Toyin Kasali
- b Biopharmaceutical Development, MedImmune Ltd , Cambridge , UK
| | - Nicholas J Bond
- b Biopharmaceutical Development, MedImmune Ltd , Cambridge , UK
| | | | - Alan Carruthers
- c Respiratory, Inflammation and Autoimmunity, MedImmune Ltd , Cambridge , UK
| | - John Hood
- e Translational Sciences, Medimmune Ltd ., Cambridge , UK
| | - M Jack Borrok
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Arnita Barnes
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Keith Rickert
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Sandrina Phipps
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Lena Shirinian
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Jie Zhu
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Michael A Bowen
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - William Dall'Acqua
- a Antibody Discovery and Protein Engineering, Medimmune LLC , Gaithersburg , MD , USA
| | - Lynne A Murray
- c Respiratory, Inflammation and Autoimmunity, MedImmune Ltd , Cambridge , UK
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Bousfield GR, Butnev VY, Rueda-Santos MA, Brown A, Hall AS, Harvey DJ. Macro- and Micro-heterogeneity in Pituitary and Urinary Follicle-Stimulating Hormone Glycosylation. ACTA ACUST UNITED AC 2014; 4. [PMID: 25722940 DOI: 10.4172/2153-0637.1000125] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
FSH glycosylation macroheterogeneity in pituitary and urinary hFSH samples was evaluated by Western blotting. Microheterogeneity in two highly purified urinary and pituitary hFSH preparations was evaluated by nano-electrospray mass spectrometry of peptide-N-glycanase-released oligosaccharides. An age-related loss of hypo-glycosylated hFSH in individual female pituitaries was indicated by progressively reduced abundance of hFSH21 relative to hFSH24. Urinary hFSH was evaluated as a potentially non-invasive indicator of glycoform abundance, as the only way for pituitary FSH to reach the urine is through the blood. Both highly purified and crude postmenopausal urinary hFSH preparations possessed the same amount of hFSH21 as postmenopausal pituitary gland FSH. Considerable microheterogeneity was encountered in both pituitary and urinary hFSH glycan populations, as 84 pituitary hFSH glycan ions were observed as compared with 68 urinary hFSH glycans. The biggest quantitative differences between the two populations were reduced abundance of bisecting GlcNAc-containing and fucosylated glycans, along with sulfated glycans in the urinary hFSH glycan population. The relative abundance of sialic acid and glycan antenna did not rationalize the retarded electrophoretic mobilities of the urinary hFSHβ21- and α-subunit bands relative to the corresponding pituitary hFSH bands, as the most abundant glycans in the former possessed only 2 more branches and the same sialic content as in the latter. Site-specific glycosylation information will probably be necessary.
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Affiliation(s)
- George R Bousfield
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260
| | - Vladimir Y Butnev
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260
| | | | - Alan Brown
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260
| | - Aaron Smalter Hall
- Molecular Graphics and Modeling Laboratory, University of Kansas, Lawrence, KS 66045
| | - David J Harvey
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, UK
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Trahtenherts A, Benhar I. An internalizing antibody specific for the human asialoglycoprotein receptor. Hybridoma (Larchmt) 2009; 28:225-33. [PMID: 19663694 DOI: 10.1089/hyb.2009.0019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The liver possesses a variety of characteristics that make this organ a very attractive target for gene and drug delivery. The asialoglycoprotein receptor (ASGPR) is a heterodimeric liver-specific C-type lectin that mediates endocytosis and degradation of desialylated glycoproteins and is considered a preferable target for liver-specific drug delivery. Asialoglycoprotein-coupled, galactosylated, or anti-ASGPR antibody-targeted molecules may be used to deliver pharmaceutical agents to the liver. Here we present a new anti-ASGPR single-chain antibody (scFv) that was isolated from the synthetic human "Ronit-1" antibody phage display library. This scFv (B11) was shown to bind the recombinant and native forms of the ASGPR and could also facilitate ASGPR specific internalization of a B11-PE38KDEL immunotoxin and cause cell death. Thus, this newly isolated antibody can serve as a targeting moiety for ASGPR-directed drug delivery.
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Affiliation(s)
- Alla Trahtenherts
- Department of Molecular Microbiology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel
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Abstract
The four essential building blocks of cells are proteins, nucleic acids, lipids, and glycans. Also referred to as carbohydrates, glycans are composed of saccharides that are typically linked to lipids and proteins in the secretory pathway. Glycans are highly abundant and diverse biopolymers, yet their functions have remained relatively obscure. This is changing with the advent of genetic reagents and techniques that in the past decade have uncovered many essential roles of specific glycan linkages in living organisms. Glycans appear to modulate biological processes in the development and function of multiple physiologic systems, in part by regulating protein-protein and cell-cell interactions. Moreover, dysregulation of glycan synthesis represents the etiology for a growing number of human genetic diseases. The study of glycans, known as glycobiology, has entered an era of renaissance that coincides with the acquisition of complete genome sequences for multiple organisms and an increased focus upon how posttranslational modifications to protein contribute to the complexity of events mediating normal and disease physiology. Glycan production and modification comprise an estimated 1% of genes in the mammalian genome. Many of these genes encode enzymes termed glycosyltransferases and glycosidases that reside in the Golgi apparatus where they play the major role in constructing the glycan repertoire that is found at the cell surface and among extracellular compartments. We present a review of the recently established functions of glycan structures in the context of mammalian genetic studies focused upon the mouse and human species. Nothing tends so much to the advancement of knowledge as the application of a new instrument. The native intellectual powers of men in different times are not so much the causes of the different success of their labours, as the peculiar nature of the means and artificial resources in their possession. T. Hager: Force of Nature (1)
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Affiliation(s)
- John B Lowe
- Department of Pathology and Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.
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Ellies LG, Ditto D, Levy GG, Wahrenbrock M, Ginsburg D, Varki A, Le DT, Marth JD. Sialyltransferase ST3Gal-IV operates as a dominant modifier of hemostasis by concealing asialoglycoprotein receptor ligands. Proc Natl Acad Sci U S A 2002; 99:10042-7. [PMID: 12097641 PMCID: PMC126621 DOI: 10.1073/pnas.142005099] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A number of poorly characterized genetic modifiers contribute to the extensive variability of von Willebrand disease, the most prevalent bleeding disorder in humans. We find that a genetic lesion inactivating the murine ST3Gal-IV sialyltransferase causes a bleeding disorder associated with an autosomal dominant reduction in plasma von Willebrand factor (VWF) and an autosomal recessive thrombocytopenia. Although both ST3Gal-IV and ST6Gal-I sialyltransferases mask galactose linkages implicated as asialoglycoprotein receptor ligands, only ST3Gal-IV deficiency promotes asialoglycoprotein clearance mechanisms with a reduction in plasma levels of VWF and platelets. Exposed galactose on VWF was also found in a subpopulation of humans with abnormally low VWF levels. Oligosaccharide branch-specific sialylation by the ST3Gal-IV sialyltransferase is required to sustain the physiologic half-life of murine hemostatic components and may be an important modifier of plasma VWF level in humans.
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Affiliation(s)
- Lesley G Ellies
- Howard Hughes Medical Institute and Department of Cellular and Molecular Medicine, 9500 Gilman Drive 0625, University of California San Diego, La Jolla, CA 92093, USA
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Yi D, Lee RT, Longo P, Boger ET, Lee YC, Petri WA, Schnaar RL. Substructural specificity and polyvalent carbohydrate recognition by the Entamoeba histolytica and rat hepatic N-acetylgalactosamine/galactose lectins. Glycobiology 1998; 8:1037-43. [PMID: 9719685 DOI: 10.1093/glycob/8.10.1037] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Both the Entamoeba histolytica lectin, a virulence factor for the causative agent of amebiasis, and the mammalian hepatic lectin bind to N-acetylgalactosamine (GalNAc) and galactose (Gal) nonreducing termini on oligosaccharides, with preference for GalNAc. Polyvalent GalNAc-derivatized neoglycoproteins have >1000-fold enhanced binding affinity for both lectins (Adler,P., Wood,S.J., Lee,Y.C., Lee,R.T., Petri,W.A.,Jr. and Schnaar,R.L.,1995, J. Biol. Chem ., 270, 5164-5171). Substructural specificity studies revealed that the 3-OH and 4-OH groups of GalNAc were required for binding to both lectins, whereas only the E.histolytica lectin required the 6-OH group. Whereas GalNAc binds with 4-fold lower affinity to the E.histolytica lectin than to the mammalian hepatic lectin, galactosamine and N-benzoyl galactosamine bind with higher affinity to the E. histolytica lectin. Therefore, a synthetic scheme for converting polyamine carriers to poly-N-acyl galactosamine derivatives (linked through the galactosamine primary amino group) was developed to test whether such ligands would bind the E.histolytica lectin with high specificity and high affinity. Contrary to expectations, polyvalent derivatives including GalN6lys5, GalN4desmosine, GalN4StarburstTMdendrimer, and GalN8StarburstTMdendrimer demonstrated highly enhanced binding to the mammalian hepatic lectin but little or no enhancement of binding to the E.histolytica lectin. We propose that the mammalian hepatic lectin binds with greatest affinity to GalNAc "miniclusters," which mimic branched termini of N-linked oligosaccharides, whereas the E.histolytica lectin binds most effectively to "maxiclusters," which may mimic more widely spaced GalNAc residues on intestinal mucins.
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Affiliation(s)
- D Yi
- Departments of Pharmacology and Neuroscience, The Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
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