1.
Venkatakrishnan, Vignesh, 1987, et al.
(författare)
Novel inhibitory effect of galectin-3 on the respiratory burst induced by Staphylococcus aureus in human neutrophils
2023
Ingår i: Glycobiology. - : OXFORD UNIV PRESS INC. - 1460-2423 .- 0959-6658. ; 33:6, s. 503-511
Tidskriftsartikel (refereegranskat) abstract
Among the responders to microbial invasion, neutrophils represent the earliest and perhaps the most important immune cells that contribute to host defense with the primary role to kill invading microbes using a plethora of stored anti-microbial molecules. One such process is the production of reactive oxygen species (ROS) by the neutrophil enzyme complex NADPH-oxidase, which can be assembled and active either extracellularly or intracellularly in phagosomes (during phagocytosis) and/or granules (in the absence of phagocytosis). One soluble factor modulating the interplay between immune cells and microbes is galectin-3 (gal-3), a carbohydrate-binding protein that regulates a wide variety of neutrophil functions. Gal-3 has been shown to potentiate neutrophil interaction with bacteria, including Staphylococcus aureus, and is also a potent activator of the neutrophil respiratory burst, inducing large amounts of granule-localized ROS in primed cells. Herein, the role of gal-3 in regulating S. aureus phagocytosis and S. aureus-induced intracellular ROS was analyzed by imaging flow cytometry and luminol-based chemiluminescence, respectively. Although gal-3 did not interfere with S. aureus phagocytosis per se, it potently inhibited phagocytosis-induced intracellular ROS production. Using the gal-3 inhibitor GB0139 (TD139) and carbohydrate recognition domain of gal-3 (gal-3C), we found that the gal-3-induced inhibitory effect on ROS production was dependent on the carbohydrate recognition domain of the lectin. In summary, this is the first report of an inhibitory role of gal-3 in regulating phagocytosis-induced ROS production.
2.
Sabirsh, A, et al.
(författare)
Fluorescent leukotriene B-4: potential applications
2005
Ingår i: Journal of Lipid Research. - 1539-7262 .- 0022-2275. ; 46:6, s. 1339-1346
Tidskriftsartikel (refereegranskat) abstract
Leukotriene B-4 (LTB4) is a potent lipid mediator of inflammation that acts primarily via a seven-transmembrane-spanning, G-protein-coupled receptor denoted BLT1. Here, we describe the synthesis and characterization of fluorescent analogs of LTB4 that are easy to produce, inexpensive, and without the disadvantages of a radioligand. Fluorescent LTB4 is useful for labeling LTB4 receptors for which no antibodies are available and for performing one-step fluorescence polarization assays conducive to high-throughput screening. We found that orange and green fluorescent LTB4 were full agonists that activated the LTB4 receptor BLT1 with EC50 values of 68 and 40 nM, respectively (4.5 nM for unmodified LTB4). Flow cytometric measurements and confocal imaging showed that fluorescent LTB4 colocalized with BLT1. Fluorescence polarization measurements showed that orange fluorescent LTB4 bound to BLT1 with a K-d of 66 nM and that this binding could be displaced by unlabeled LTB4 and other BLT1-specific ligands. Fluorescent LTB4 analogs were also able to displace tritiated LTB4. Orange fluorescent LTB4 binding to enhanced green fluorescent protein-tagged BLT1 could be observed using fluorescence resonance energy transfer. In addition to being a useful alternative to radiolabeled LTB4, the unique properties of fluorescently labeled LTB4 allow a variety of detection technologies to be used.
3.
Almkvist, Jenny, 1971, et al.
(författare)
Lipopolysaccharide-induced gelatinase granule mobilization primes neutrophils for activation by galectin-3 and formylmethionyl-Leu-Phe.
2001
Ingår i: Infection and immunity. - 0019-9567 .- 1098-5522. ; 69:2, s. 832-7
Tidskriftsartikel (refereegranskat) abstract
We have earlier shown that galectin-3, a lactose-binding mammalian lectin that is secreted from activated macrophages, basophils, and mast cells, induces activation of the NADPH oxidase in exudated but not in peripheral blood neutrophils (A. Karlsson, P. Follin, H. Leffler, and C. Dahlgren, Blood 91:3430-3438, 1998). The alteration in responsiveness occurring during extravasation correlated with mobilization of the gelatinase and/or specific granules to the cell surface, indicating a role for mobilizable galectin-3 receptors. In this study we have investigated galectin-3-induced NADPH oxidase activation, measured as superoxide production, in lipopolysaccharide (LPS)-primed neutrophils. Upon galectin-3 challenge, the LPS-primed cells produced superoxide, both extracellularly and intracellularly. A primed extracellular response to formylmethionyl-Leu-Phe (fMLF) was also achieved. The exposure of complement receptors 1 and 3 as well as the formyl peptide receptor on the cell surface was markedly increased after LPS treatment, indicating that granule fusion with the plasma membrane had occurred. Further assessment of specific markers for neutrophil granules showed that the LPS treatment had mobilized the gelatinase granules but only a minor fraction of the specific granules. We thus suggest that the mechanism behind LPS priming lies at the level of granule (receptor) mobilization for galectin-3 as well as for fMLF.
4.
Almkvist, Jenny, 1971, et al.
(författare)
Newcastle disease virus neuraminidase primes neutrophils for stimulation by galectin-3 and formyl-Met-Leu-Phe
2004
Ingår i: Experimental cell research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 298:1, s. 74-82
Tidskriftsartikel (refereegranskat) abstract
Human neutrophils are activated by the beta-galactoside-binding lectin galectin-3, provided that the cells are primed by in vivo extravasation or by in vitro preactivation with, for example, LPS. Removal of terminal sialic acid can change neutrophil functionality and responsiveness due to exposure of underlying glycoconjugate receptors or change in surface charge. Here, we investigated whether such alteration of the cell surface carbohydrate composition can alter the responsiveness of the cells to galectin-3. Neutrophils were treated with neuraminidases (NA) of different origins: Clostridium perfringens (CP), Salmonella typhimurium, Vibrio cholerae, and Newcastle disease virus (NDV). In the presence of NDV-NA, but no other NA, the otherwise non-responding neutrophils responded readily to galectin-3 by activation of the NADPH-oxidase. The galectin-3 priming effect was inhibited by the sialidase inhibitor 2,3-dehydro-2-deoxy-N-acetyl-neuraminic acid. Earlier studies have shown that priming of the neutrophil response to galectin-3 with, for example, LPS is paralleled by degranulation of intracellular vesicles and granules and upregulation of potential galectin-3 receptors. Also, NDV-NA (but not CP-NA) treatment induced degranulation, shown as an upregulation of complement receptor 3. Since not only the galectin response but also the response to the chemoattractant fMLF was primed, NDV-NA appears to induce a general priming phenomenon, possibly due to receptor upregulation by degranulation.
5.
6.
Bergh, Anders, et al.
(författare)
Cobalt-mediated solid phase synthesis of 3-O-alkynylbenzyl galactosides and their evaluation as galectin inhibitors
2006
Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 62:35, s. 8309-8317
Tidskriftsartikel (refereegranskat) abstract
Methyl beta-D-galactoside was converted to the corresponding 3,4-O-stannylene acetal, which was selectively benzylated with 3-iodobenzyl bromide and coupled to a polymer-bound propargylic ether via a Sonogashira reaction. The polymer-bound carbohydrate substrate was cleaved from the resin with different carbon nucleophiles in a cobalt-mediated Nicholas reaction. The product 3-O-alkynylbenzyl galactosides were screened towards galectin-1, -3, -7, -8N and -9N in a competitive fluorescence polarisation assay. Particularly potent inhibitors were identified against galectin-7 with affinity enhancements up to one order of magnitude due to the 3-O-alkynylbenzyl moiety. (c) 2006 Elsevier Ltd. All rights reserved.
7.
Bum-Erdene, Khuchtumur, et al.
(författare)
Investigation into the Feasibility of Thioditaloside as a Novel Scaffold for Galectin-3-Specific Inhibitors
2013
Ingår i: ChemBioChem. - : Wiley. - 1439-4227. ; 14:11, s. 1331-1342
Tidskriftsartikel (refereegranskat) abstract
Galectin-3 is extensively involved in metabolic and disease processes, such as cancer metastasis, thus giving impetus for the design of specific inhibitors targeting this -galactose-binding protein. Thiodigalactoside (TDG) presents a scaffold for construction of galectin inhibitors, and its inhibition of galectin-1 has already demonstrated beneficial effects as an adjuvant with vaccine immunotherapy, thereby improving the survival outcome of tumour-challenged mice. A novel approachreplacing galactose with its C2 epimer, taloseoffers an alternative framework, as extensions at C2 permit exploitation of a galectin-3-specific binding groove, thereby facilitating the design of selective inhibitors. We report the synthesis of thioditaloside (TDT) and crystal structures of the galectin-3 carbohydrate recognition domain in complexes with TDT and TDG. The different abilities of galactose and talose to anchor to the protein correlate with molecular dynamics studies, likely explaining the relative disaccharide binding affinities. The feasibility of a TDT scaffold to enable access to a particular galectin-3 binding groove and the need for modifications to optimise such a scaffold for use in the design of potent and selective inhibitors are assessed.
8.
Cumpstey, Ian, et al.
(författare)
Double Affinity Amplification of Galectin-Ligand Interactions through Arginine-Arene Interactions: Synthetic, Thermodynamic, and Computational Studies with Aromatic Diamido-Thiodigalactosides.
2008
Ingår i: Chemistry: A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 14:14, s. 4233-4245
Tidskriftsartikel (refereegranskat) abstract
A series of aromatic mono- or diamido-thiodigalactoside derivatives were synthesized and studied as ligands for galectin-1, -3, -7, -8N terminal domain, and -9N terminal domain. The affinity determination in vitro with competitive fluorescence-polarization experiments and thermodynamic analysis by isothermal microcalorimetry provided a coherent picture of structural requirements for arginine-arene interactions in galectin-ligand binding. Computational studies were employed to explain binding preferences for the different galectins. Galectin-3 formed two almost ideal arene-arginine stacking interactions according to computer modeling and also had the highest affinity for the diamido-thiodigalactosides (K(d) below 50 nM). Site-directed mutagenesis of galectin-3 arginines involved in binding corroborated the importance of their interaction with the aromatic diamido-thiodigalactosides. Furthermore, the arginine mutants revealed distinct differences between free, flexible, and solvent-exposed arginine side chains and tightly ion-paired arginine side chains in interactions with aromatic systems.
9.
Cumpstey, Ian, et al.
(författare)
Studies of arginine-arene interactions through synthesis and evaluation of a series of galectin-binding aromatic lactose esters
2007
Ingår i: ChemBioChem. - : Wiley. - 1439-4227 .- 1439-7633. ; 8:12, s. 1389-1398
Tidskriftsartikel (refereegranskat) abstract
Aromatic lactose 2-O-esters were synthesized and used to probe arene-arginine interactions with the galectin family of proteins. They were found to be low mu m inhibitors of galectin-1, -3, and -9N-terminal domain and moderate inhibitors of galectin-7, but not inhibitors of galectin-8N-terminal, which locks an arginine residue close to the critical, esterified lactose 2-O-position. Molecular modeling of galectins in complex with aromatic lactose 2-O-esters, as well as binding studies with a galectin-3 R186S mutant, confirmed that the inhibitory efficiency of the lactose 2-O-esters was due to the formation of strong interactions between the aromatic ester moieties and the arginine guanidinium groups of galectin-1 and -3. An important common feature shared by galectin-1 and -3 was that the arginines formed in-plane ion pairs with two side-chain carboxylates, which resulted in extended planar pi-electron surfaces that did not require solvation by water; these surfaces were ideal for stocking with aromatic moieties of the ligands. The results provide a basis for the design of lectin inhibitors and drugs that exploit interactions with arginine side-chains via aromatic moieties, which are involved in intramolecular protein salt bridges.
10.
Delacour, Delphine, et al.
(författare)
Apical sorting by galectin-3-dependent glycoprotein clustering
2007
Ingår i: Traffic: the International Journal of Intracellular Transport. - : Wiley. - 1398-9219. ; 8:4, s. 379-388
Tidskriftsartikel (refereegranskat) abstract
Epithelial cells are characterized by their polarized organization based on an apical membrane that is separated from the basolateral membrane domain by tight junctions. Maintenance of this morphology is guaranteed by highly specific sorting machinery that separates lipids and proteins into different carrier populations for the apical or basolateral cell surface. Lipid-raft-independent apical carrier vesicles harbour the beta-galactoside-binding lectin galectin-3, which interacts directly with apical cargo in a glycan-dependent manner. These glycoproteins are mistargeted to the basolateral membrane in galectin-3-depleted cells, dedicating a central role to this lectin in raft-independent sorting as apical receptor. Here, we demonstrate that high-molecular-weight clusters are exclusively formed in the presence of galectin-3. Their stability is sensitive to increased carbohydrate concentrations, and cluster formation as well as apical sorting are perturbed in glycosylation-deficient Madin-Darby canine kidney (MDCK) II cells. Together, our data suggest that glycoprotein cross-linking by galectin-3 is required for apical sorting of non-raft-associated cargo.
