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Query: UNIPROT:P17931 (galectin-3)
 2,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Galectin-3 is an important intracellular and extracellular lectin which is presumed to interact with extracellular matrix proteins and cell surface glycoproteins in normal and pathophysiological conditions. The exact physiological role of the protein is presently not known. We have previously demonstrated that recombinant human galectin-3 is a novel substrate for metalloproteinases, particularly MMP-2 and MMP-9. These enzymes are capable of efficiently cleaving the Ala62-Tyr63 bond of the ca. 30 kDa galectin-3, generating a 22 kDa fragment with intact carbohydrate recognition domain and a ca. 9 kDa polypeptide comprising the amino terminal end of the intact galectin-3. In this study, we analyzed interactions of the 22 kDa fragment of galectin-3 with immobilized laminins. We have also compared the hemagglutination as well as homodimerization potentials of this fragment with that of intact galectin-3. Our data suggest that cleavage of galectin-3 by metalloproteinases; (a) alters the carbohydrate recognition domain of the lectin so that it binds more tightly to the glycoconjugates and, (b) reduces selfassociation of the galectin molecules thereby abrogating the biological properties dependent on such associations or homodimerization.
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PMID:Modulation of the biological functions of galectin-3 by matrix metalloproteinases. 946 37

Galectin-3 is a member of a large family of beta-galactoside-binding animal lectins and is composed of a carboxyl-terminal lectin domain connected to an amino-terminal nonlectin part. Previous experimental results suggest that, when bound to multivalent glycoconjugates, galectin-3 self-associates through intermolecular interactions involving the amino-terminal domain. In this study, we obtained evidence suggesting that the protein self-associates in the absence of its saccharide ligands, in a manner that is dependent on the carboxyl-terminal domain. This mode of self-association is inhibitable by the lectin's saccharide ligands. Specifically, recombinant human galectin-3 was found to bind to galectin-3C (the carboxyl-terminal domain fragment) conjugated to Sepharose 4B and the binding was inhibitable by lactose. In addition, biotinylated galectin-3 bound to galectin-3 immobilized on plastic surfaces and the binding could also be inhibited by various saccharide ligands of the lectin. A mutant with a tryptophan to leucine replacement in the carboxyl-terminal domain, which exhibited diminished carbohydrate-binding activity, did not bind to galectin-3C-Sepharose 4B. Furthermore, galectin-3C formed covalent homodimers when it was treated with a chemical cross-linker and the dimer formation was completely inhibited by lactose. Therefore, galectin-3 can self-associate through intermolecular interactions involving both the amino- and the carboxyl-terminal domains and the relative contribution of each depends on whether the lectin is bound to its saccharide ligands.
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PMID:Role of the carboxyl-terminal lectin domain in self-association of galectin-3. 952 30

Galectins are a family of lectins which share similar carbohydrate recognition domains (CRDs) and affinity for small beta-galactosides, but which show significant differences in binding specificity for more complex glycoconjugates. We report here the x-ray crystal structure of the human galectin-3 CRD, in complex with lactose and N-acetyllactosamine, at 2.1-A resolution. This structure represents the first example of a CRD determined from a galectin which does not show the canonical 2-fold symmetric dimer organization. Comparison with the published structures of galectins-1 and -2 provides an explanation for the differences in carbohydrate-binding specificity shown by galectin-3, and for the fact that it fails to form dimers by analogous CRD-CRD interactions.
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PMID:X-ray crystal structure of the human galectin-3 carbohydrate recognition domain at 2.1-A resolution. 958 41

Galectins (S-type lectins) are a family of low-molecular weight, calcium-independent, mannose-binding lectins with functions in cell growth, cell activation, cell-cell and cell-matrix adhesion including binding to carcinoembryonic antigens and laminin and metalloproteinase. Anti-galectin antisera can inhibit metastases of rat prostate cancers and human melanomas. To define the role of galectins in human breast cancer, the expression of galectin-3 were determined in 27 invasive breast cancers by immunohistochemical methods. The histologic grades of excised breast cancers were determined and immunohistochemical staining for galectin-3 (1: 1000 dilution of anti-galectin rat polyclonal antibody) was defined by scoring the intensity and distribution of staining (0-3+). The mean age of breast cancer patients was 63 years for 20 grade II breast cancers and 56 years for 7 grade III breast cancers. The mean immunohistochemical staining score for grade II breast cancers was 3. 7 (20% less than 2, 80% 3-6) and 2.5 for grade III (71.4% less than 2 and 28.6% 3-6). The galectin-3 expression pattern suggests that increasing histologic grade of breast cancer leads to reduced expression of galectin-3 and possibly reduced matrix binding and increased cancer cell motility.
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PMID:Galectin-3 expression in human breast carcinoma: correlation with cancer histologic grade. 959 87

Antisera raised against galectin-1 exhibit crossreactivities with other galectins or related molecules. In order to overcome this problem, a monoclonal antibody to human brain galectin-1 was obtained by selecting clones without reactivity toward galectin-3. This mAb specifically bound galectin-1 of various animal origins but neither galectin-2 nor galectin-3. Western-blotting analysis of soluble human brain extracts after 2D gel electrophoresis revealed only the two most acidic isoforms of galectin-1. The ability of this mAb to bind galectin-1/asialofetuin complexes indicates that its epitope is not localized in the carbohydrate recognition domain of galectin-1. This particularity induces with efficiency its monospecificity.
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PMID:Production and characterization of a monoclonal antibody able to discriminate galectin-1 from galectin-2 and galectin-3. 959 40

Tumor cell adhesion and migration to laminin are important events during invasion and metastatic spread. Galectin-3, a multifunctional member of the galectin family, binds specifically the poly-N-acetyllactosamine residues of laminin and has been implicated in tumor invasion and metastasis. Galectin-3 is multimerized by transglutaminase, an enzyme that catalyzes cross-linking between glutamine and other aminoacid residues. In this study, we examined the consequences of transglutaminase-mediated galectin-3 oligomerization on the interactions between cancer cells and laminin. We first demonstrated that human galectin-3 is cross-linked by guinea pig liver transglutaminase, forms oligomers, and incorporates the marker 5-(biotinamido) pentylamine. Expression of transglutaminase activity in the A375 and A2058 human melanoma cell extracts was revealed by its ability to induce galectin-3 oligomerization and 5-(biotinamido) pentylamine incorporation. Transglutaminase-treated galectin-3 did not affect adhesion or migration of the melanoma cells to laminin but consistently induced a significant increase of the percentage of cell spreading compared to the control (23.5 +/- 2.3%, vs. 10.6 +/- 1.9% at 180 min, p < 0.05), or to untreated galectin-3 or transglutaminase alone. Our study is the first demonstration that human galectin-3 is oligomerized by transglutaminase with, as a consequence, a specific effect of melanoma cell spreading on laminin. This phenomenon could be of significance in the modulation of cancer cell interactions with laminin during tumor invasion and metastasis.
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PMID:Transglutaminase-mediated oligomerization of galectin-3 modulates human melanoma cell interactions with laminin. 979 24

Galectin-3 is a member of the galectin family and belongs to a group of soluble beta-galactoside-binding animal lectins. The molecule is expressed by neural and nonneural cells intra- (cytoplasm and nucleus) as well as extra-cellularly (plasma membrane and extracellular space). By using an in vitro cell-substratum adhesion assay, we have addressed the question whether galectin-3 present in the extracellular milieu may support the adhesion and/or neurite outgrowth of neural cells in a manner analogous to cell adhesion molecules. Galectin-3 was immobilized as a substratum and various cell types, N2A (neuroblastoma), PC12 (pheochromocytoma), and TSC (transformed Schwann cells) cell lines, neural cells from early postnatal mouse cerebellum, and dorsal root ganglion neurons from newborn mice were allowed to adhere to the lectin. Here we show that all cell types studied specifically adhered to galectin-3 by the following criteria: 1) the number of adherent cells was dependent on the galectin-3 concentration used for coating; 2) adhesion of cells to galectin-3, but not to collagen type I or laminin was inhibited by polyclonal antibodies to galectin-3; 3) upon addition of asialofetuin (a polyvalent carrier of terminal beta-galactosides) to the cell suspension prior to the adhesion assay, cell adhesion to galectin-3 was inhibited in a dose-dependent manner; and 4) cell adhesion to galectin-3 was abolished by treatment of cells with endo-beta-galactosidase. In addition, the adhesion of dorsal root ganglion neurons to galectin-3 could be inhibited by lactose. Notably, substratum-bound galectin-3 promoted the outgrowth of neurites from dorsal root ganglia explants and this neurite outgrowth promoting activity could be inhibited by polyclonal antibodies to galectin-3.
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PMID:Galectin-3 promotes neural cell adhesion and neurite growth. 984 55

Galectins have a wide range of biological activities which are elicited by binding to appropriate glycoligands. Besides regulation of the expression of the galectins the extent of the presence of suitable binding sites will be relevant to infer the cellular responsiveness to this class of sugar receptors. Thus ligand presentation requires monitoring by the tissue lectin. We demonstrate the expression of galectin-3 by macrophages and foreign-body giant multinucleate cells colonizing a cellophane implant in the rat by the A1D6 monoclonal antibody. The extents of ligand presence are visualized in the same cells by biotinylated galectin-3 and also by galectin-1 which is produced by diverse mammalian cell types and widely distributed. Labeled mistletoe (VAA) and tomato (LEA) lectins are used as tools to assess the degree of similarity of the binding profile between endogenous and exogenous proteins. The presentation of alpha-galactosides is monitored with a natural immunoglobulin G subfraction obtained by two consecutive affinity chromatography steps. The binding of labeled galectins and plant lectins was significantly lower to foreign-body giant multinucleate cells than to mononuclear macrophages. The application of the alpha-galactoside-specific probe yielded no significant staining. The potential problem of epitope accessibility could be excluded by the concomitant positivity obtained with an IgG subfraction with selectivity to beta-galactosides also obtained by affinity chromatography. These results provide no evidence for a role of alpha-galactosides for the binding of galectins in the rat macrophages colonizing the implant. The reduced level of expression of glycoligands for galectin-1 and -3 in foreign-body giant multinucleate cells in contrast with the mononuclear macrophages suggests an inhibitory influence of macrophage fusion on the expression of galectin-reactive molecules.
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PMID:Fusion of macrophages on an implant surface is associated with down-regulated expression of ligands for galectin-1 and -3 in the rat. 985 91

We have analyzed the expression of galectin-1 and galectin-3 in four human prostate carcinoma cell lines. Northern analysis and immunoblotting experiments showed that three cell lines express both galectins. However, only galectin-1 was detected on the surface of these cells. The LNCaP line expressed neither galectin. LNCaP was transfected with galectin-1 and four clones were isolated, all of which expressed galectin-1 on the cell surface. Kinetics of binding to extracellular matrix proteins appeared to be accelerated in the transfected lines, but overall binding was not enhanced. When the same experiments were performed in the presence of EDTA to eliminate the effects of integrins, binding of a galectin-1 clone to laminin and fibronectin was increased relative to the control cell line. We propose that galectins may contribute to the adhesive properties of some prostate cancer cells.
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PMID:Differential expression of endogenous galectin-1 and galectin-3 in human prostate cancer cell lines and effects of overexpressing galectin-1 on cell phenotype. 991 95

Cell surface complex carbohydrate structures that are synthesized through the actions of glycosyltransferases play an important role in cell-to-cell and cell-to-extracellular matrix interactions. To examine the feasibility of phage display technique to clone cDNAs encoding glycosyltransferases, we performed biopanning experiments using human histo-blood group A transferase as a model enzyme and its substrate, blood group H-specific glycoproteins, as a bait ligand. Our attempts have been unsuccessful, possibly because of the enzyme's weak affinity with the target. However, we have selectively enriched several phage clones that expressed capsid proteins fused with galectin-3, a galactose/lactose-specific animal lectin of the galectin family. These results demonstrate that this novel approach of phage display is useful in cDNA cloning of proteins with carbohydrate-binding property.
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PMID:Phage display cDNA cloning of protein with carbohydrate affinity. 1004 85


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