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PubMed1994

Separation of lectin-binding cells using polystyrene culture devices with covalently immobilized soybean agglutinin.

The plant lectin, soybean agglutinin (SBA), has been widely used to separate heterogeneous populations of cells. In the field of bone marrow transplantation, SBA has been used for partial depletion of T cells from bone marrow allografts to reduce graft-vs.-host disease. SBA's high affinity for many different tumor cells has also indicated its use as a tumor purging agent for autologous bone marrow transplants. We have compared two methods of cell separation using either soluble SBA agglutination, or SBA covalently attached to an activated polystyrene surface. The nonbinding SBA-cell populations generated by these two procedures were very similar in terms of cell recovery, light scatter properties, and phenotypic profile. Notably, both SBA- fractions were enriched in cells with the known progenitor markers, CD34, CD33, and HLA-DR, and were relatively depleted of SBA binding cells. In addition, the activity of each SBA- cell population was measured in vitro in short-term progenitor assays. Here, both SBA- populations were significantly enriched for CFU-GM. When device-separated SBA- cell populations were seeded into long-term bone marrow culture, they produced both increased progenitor activity and cell proliferation compared to unseparated BMMCs. The polystyrene technology described here could reduce or eliminate many of the drawbacks of soluble SBA agglutination, making SBA cell separation a viable and convenient technique for clinical application.

Antigens, CD↗
PubMed2004

On the possible function of Telfairia occidentalis agglutinin in the plant.

The fate of Telfairia occidentalis seed Agglutinin, TOA, has been monitored during germination. While the level of the Agglutinin in the cotyledons decreased sharply in the first three days to about half of the initial level, it stabilises at this level for the following twelve days. In this interval, Agglutinin activity becomes manifest in the radicle on the fourth day, peaking on the fifth and decreasing rapidly thereafter. In the plumule, the lectin activity becomes manifest on the sixth day, peaks on the seventh and decreases rapidly thereafter. No lectin activity is detectable in any plant tissue including the rump of the cotyledons twenty-seven days after germination. The implications of these observations on the possible role of lectins in plants are discussed.

Animals↗
PubMed2004

Genetics of ribosome-inactivating proteins.

Ribosome-inactivating proteins (RIPs) are a heterogeneous group of enzymes found mainly in plants and a few bacteria that possess N-glycosidase activity on ribosomes and a related polynucleotide adenosine glycosidase activity on naked nucleic acids. They encompass single enzymatic chains, heterodimeric toxic lectins and related agglutinins. Plants commonly produce several RIP isoforms encoded by multi-gene families. The toxic lectins possess adaptations related to their cytotoxic role.

Animals↗
PubMed1989

Adhesion of colonization factor antigen II-positive enterotoxigenic Escherichia coli strains to human enterocytelike differentiated HT-29 cells: a basis for host-pathogen interactions in the gut.

Enterotoxigenic Escherichia coli are the most common cause of travelers' and infant diarrhea in less-developed countries. In the present work, among several metabolically labeled human diarrheagenic E. coli strains, enterotoxigenic strains expressing colonization factor antigen II were shown to bind to HT-29 intestinal cell monolayers when these cells were grown in conditions promoting their enterocytic differentiation. Indirect immunofluorescence with fimbrial antisera revealed that pathogen attachment was associated with the production of a specific bacterial adhesin, the E. coli surface antigen CS3. Scanning and transmission electron micrographs showed an apical pattern of colonization, characteristic of enterotoxigenic E. coli infections. The above data were consistent with all observations previously made with human enterocytes obtained from intestinal biopsies. The lectin-carbohydrate nature of this cell-cell recognition mechanism was also established. Bacterial binding to differentiated HT-29 cells was inhibited by a mixture of newborn meconium glycopeptides. By coating the cell layers with the plant agglutinin from Evonymus europaea, pathogen attachment was also prevented. Binding of 125I-labeled CS3 adhesin and E. europaea agglutinin to brush border membrane proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose revealed three bands of about 30, 20, and 13 kilodaltons, which acted as receptors for both bacterial and plant lectins. These data suggest that the sugar units to which the bacterial colonization factor CS3 binds are synthesized as carbohydrate chains of three brush border membrane glycoproteins in HT-29 cells by a differentiation-specific pathway.

Antigens, Bacterial↗
PubMed1981

Haemagglutinins and lysins in plants and their application in characterising human and animal red cells.

Saline extracts of 207 seed varieties belonging to 53 families were tested for haemagglutinating and haemolytic activity against the erythrocytes of eleven vertebrate species (man, monkey, rabbit, rat, goat, sheep, cow, buffalo, horse, mule and fowl). Of these, 85 seed extracts showed haemagglutinating activity and 49 seed extracts showed haemolytic activity against the red cells of one or more animal species. Several seed extracts were found to react in a species specific manner agglutinating or lysing the red cells exclusively of one animal species each. The possible practical application of the species specific plant agglutinins and haemolysins in characterising the red cells of different animal species is discussed.

Animals↗
PubMed1989

The plant lectin soybean agglutinin binds to the soma, axon and central terminals of a subpopulation of small-diameter primary sensory neurons in the rat and cat.

The distribution of binding of the plant lectin soybean agglutinin to primary sensory neurons has been investigated in the rat and cat. Soybean agglutinin was found to bind to approximately 30% of neurons in the fourth, lumbar dorsal root ganglion of the rat and approximately 50% of neurons in the first, sacral dorsal root ganglion in the cat. Morphometric analysis of these dorsal root ganglia revealed that in both species those neurons which bind soybean agglutinin appear to be a subpopulation of the small-diameter cells. Electron microscopic analysis of the lumbar dorsal roots revealed that soybean agglutinin binds to the plasma membrane of a subpopulation of unmyelinated axons in both species. Myelinated axons did not bind the lectin. In the dorsal horn of the spinal cord, soybean agglutinin bound to components of Lissauer's tract and the superficial laminae (laminae I and II) of the dorsal horn in both species. In the dorsal horn lectin binding was limited to lamina I and the outer portion of lamina II (sublamina IIo) in the cat, while in the rat lamina I and the entire dorsoventral extent of lamina II (sublaminae IIo and IIi) were labelled. Thirty days following dorsal rhizotomy, soybean agglutinin binding in the superficial dorsal horn, ipsilateral to the rhizotomy, was abolished in both species. These results show the plant lectin soybean agglutinin to be a histochemical marker for the soma and central terminals of a subpopulation of small-diameter sensory neurons in both the rat and cat. It is suggested that soybean agglutinin binding may be used in conjunction with immunohistochemistry to allow identification of putative neurotransmitters within, or in synaptic profiles associated with, the central terminals of small-diameter primary sensory neurons.

Animals↗
PubMed2003

First demonstration of differential inhibition of lectin binding by synthetic tri- and tetravalent glycoclusters from cross-coupling of rigidified 2-propynyl lactoside.

The interplay of mammalian lectins such as galectins with cellular glycoconjugates is intimately involved in crucial reaction pathways including tumor cell adhesion, migration or growth regulation. These clinically relevant functions explain the interest in designing glycoclusters with potent activity to interfere with lectin binding. In view of the perspective for medical applications the following objective arises: to correlate topological factors of ligand display most favorably to reactivity against endogenous lectins. To date, plant agglutinins have commonly been used as models. Properly addressing this issue we first prepared di- to tetravalent clusters from 2-propynyl lactoside under mild oxidative homocoupling conditions and using the Sonogashira palladium-catalyzed cross-coupling reaction with triiodobenzene or pentaerythritol cores. These products were tested for bioactivity in a competitive solid-phase assay using different labeled sugar receptors as probes, i,e. the beta-trefoil mistletoe lectin, the natural lactoside-binding immunoglobulin G fraction from human serum and three mammalian galectins from two subgroups. The lactose headgroups in the derivatives retained ligand properties. Differences in inhibitory capacity were marked between the galectins. In contrast to homodimeric proto-type galectins-1 and -7 significant inhibition of galectin-3 binding with a 7-fold increase in relative potency was observed for the trivalent compound. In comparison, the binding of the beta-trefoil mistletoe agglutinin was reduced best by tetravalent substances The result for galectin-3 was independently confirmed by haemagglutination and cytofluorometric cell binding assays. These data underline the feasibility of galectin-type target selectivity by compound design despite using an identical headgroup (lactose) in synthesis.

Agglutinins↗
PubMed1992

The mannose-specific plant lectins from Cymbidium hybrid and Epipactis helleborine and the (N-acetylglucosamine)n-specific plant lectin from Urtica dioica are potent and selective inhibitors of human immunodeficiency virus and cytomegalovirus replication in vitro.

A series of four mannose(Man)-, three N-acetylglucosamine (GlcNAc)n-, ten N-acetylgalactosamine/galactose(GalNAc/Gal)-, one 5-acetylneuraminic acid (alpha-2,3-Gal/GalNAc)- and one 5-acetylneuroaminic acid(alpha-2,6-Gal/Gal-NAc)-specific plant agglutinins were evaluated for their antiviral activity in vitro. the mannose-specific lectins from the orchid species Cymbidium hybrid (CA), Epipactis helleborine (EHA) and Listera ovata (LOA) were highly inhibitory to human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) in MT-4, and showed a marked anti-human cytomegalovirus (CMV), respiratory syncytial virus (RSV) and influenza A virus activity in HEL, HeLa and MDCK cells, respectively. The 50% effective concentration (EC50) of CA and EHA for HIV ranged from 0.04 to 0.08 micrograms/ml, that is about 3 orders of magnitude below their toxicity threshold (50% inhibitory concentration for MT-4 cell growth: 54 to 60 micrograms/ml). Also, the (GlcNAc)n-specific lectin from Urtica dioica (UDA) was inhibitory to HIV-1-, HIV-2-, CMV-, RSV- and influenza A virus-induced cytopathicity at an EC50 ranging from 0.3 to 9 micrograms/ml. The GalNAc/Gal-, alpha-2,3-Gal/GalNAc- or alpha-2,6-Gal/GalNAc-specific lectins were not inhibitory to HIV or CMV at non-toxic concentrations. CA, EHA and UDA proved to be potent inhibitors of syncytium formation between persistently HIV-1- and HIV-2-infected HUT-78 cells and CD4+ Molt/4 (clone 8) cells (EC50: 0.2-2 micrograms/ml). Unlike dextran sulfate, the plant lectins CA, EHA and UDA did not interfere with HIV-1 adsorption to MT-4 cells and RSV- and influenza A virus adsorption to HeLa and MDCK cells, respectively. They presumably interact at the level of virion fusion with the target cell.

Acetylglucosamine↗
PubMed1995

Differences of phenotype and gene frequency by C system in canine species.

The canine C blood group was determined by an agglutination reaction with a plant agglutinin extracted from the seeds of Clerodendron trichotomum (CTL). A positive agglutination reaction was classified as type C and a negative reaction as type c. In this study, the C phenotype and the gene frequency of C were examined in 377 dogs (224 purebred dogs of 29 breeds and 153 mongrel dogs) that were bred in Utsunomiya-city, Tochigi Prefecture. Phenotype C was less frequent than phenotype c in every purebred dog. A variation in C gene frequency was observed among the purebred dogs. The highest frequency of C allele was in the Yorkshire Terrier (0.202), followed by Beagle, Shiba (0.091), Maltese (0.085), Shi Tzu (0.051) and Shetland Sheepdog (0.036). The C blood group system as a genetic marker may provide useful information for bleed identification, genetic studies between breeds, and pedigree certification.

Animals↗
PubMed2000

Identification of distant homologues of fibroblast growth factors suggests a common ancestor for all beta-trefoil proteins.

Determination of the structures of fibroblast growth factors and interleukin-1s has previously revealed that they both adopt a beta-trefoil fold, similar to those found in Kunitz soybean trypsin inhibitors, ricin-like toxins, plant agglutinins and hisactophilin. These families possess distinct functions and occur in different subcellular localisations, and they appear to lack significant similarities in their sequences, ligands and modes of ligand binding. We have analysed the significance of sequence identities observed after structure alignment and provide statistical evidence that these beta-trefoil proteins are all homologues, having arisen from a common ancestor. In addition, we have explored the sequence space of all beta-trefoil proteins and have determined that the actin-binding proteins fascins, and other proteins of unknown function, are beta-trefoil family homologues. Unlike other beta-trefoil proteins, the triplicated repeats in each of the four beta-trefoil domains of fascins are significantly similar in sequence. This hints at how the beta-trefoil fold arose from the duplication of an ancestral gene encoding a homotrimeric single-repeat protein. The combined analysis of structure and sequence databases for detecting significant similarities is suggested as a highly sensitive approach to determining the common ancestry of extremely divergent homologues.

Amino Acid Sequence↗
PubMed2006

Glycosyldisulfides from dynamic combinatorial libraries as O-glycoside mimetics for plant and endogenous lectins: their reactivities in solid-phase and cell assays and conformational analysis by molecular dynamics simulations.

Dynamic combinatorial library design exploiting the thiol-disulfide exchange readily affords access to glycosyldisulfides. In order to reveal lectin-binding properties of this type of non-hydrolyzable sugar derivative, libraries originating from a mixture of common building blocks of natural glycans and thiocompounds were tested against three plant agglutinins with specificity to galactose, fucose or N-acetylgalactosamine, respectively, in a solid-phase assay. Extent of lectin binding to matrix-immobilized neoglycoprotein presenting the cognate sugar could be reduced, and evidence for dependence on type of carbohydrate was provided by dynamic deconvolution. Glycosyldisulfides also maintained activity in assays of increased physiological relevance, that is, using native tumor cells and also adding to the test panel an endogenous lectin (galectin-3) involved in tumor spread and cardiac dysfunction. N-Acetylgalactosamine was pinpointed as the most important building block of libraries for the human lectin and the digalactoside as most potent compound acting on the toxic mistletoe agglutinin which is closely related to the biohazard ricin. Because this glycosyldisulfide, which even surpasses lactose in inhibitory capacity, rivals thiodigalactoside as inhibitor, their degrees of intramolecular flexibility were comparatively analyzed by computational calculations. Molecular dynamics runs with explicit consideration of water molecules revealed a conspicuously high degree of potential for shape alterations by the disulfide's three-bond system at the interglycosidic linkage. The presented evidence defines glycosyldisulfides as biologically active ligands for lectins.

Binding Sites↗
PubMed1975

Immunologic evidence for addition of oviductal components to the hamster zona pellucida.

An indirect immunofluorescent procedure was used to determine whether zonae of unfertilized and fertilized eggs would bind antibodies specific for hamster reproductive tract antigens. Appropriate controls indicated that the fluorescent staining was probably due to antigen-antibody interactions. Antigens were not detected in zonae of ovarian eggs. However, components in zonae of unfertilized eggs collected from the oviduct at metestrus, mid-diestrus, and late diestrus bound antibodies specific for oviductal and uterine antigens. The antigens appeared to be concentrated in a peripheral band within the zona. An outer area of the zona around the eggs obtained from the uterus at proestrus also bound the antibodies, although the fluorescent staining was relatively faint. Antigens were observed in the peripheral area of zonae of fertilized eggs collected from oviducts on days 1 and 2 postcoitum. However, the antibody-binding component of the zona was noticeably reduced in embryos taken from the uterus on day 3 of pregnancy. The results are consistent with the idea that the zonae of both unfertilized and fertilized hamster eggs are composed of layers and that the outer region contains specific antigens which are dereived from the oviduct. Furthermore, loss or alteration of these components in the zona of an embryo (but not of an unfertilized egg of the same postovulation age) may reflect some chemical or structural change which is a prerequisite for zona shedding. Anti-uterus sera (unabsorbed and absorbed) did not interfere with zona removal by trypsin, indicating that the antigens detected in the present study are different from the receptor sites which bind anti-ovary antibodies and certain plant agglutinins (as reported by other workers).

Animals↗
PubMed2001

Glycohistochemistry: the why and how of detection and localization of endogenous lectins.

The central dogma of molecular biology limits the downstream flow of genetic information to proteins. Progress from the last two decades of research on cellular glycoconjugates justifies adding the enzymatic production of glycan antennae with information-bearing determinants to this famous and basic pathway. An impressive variety of regulatory processes including cell growth and apoptosis, folding and routing of glycoproteins and cell adhesion/migration have been unravelled and found to be mediated or modulated by specific protein (lectin)-carbohydrate interactions. The conclusion has emerged that it would have meant missing manifold opportunities not to recruit the sugar code to cellular information transfer. Currently, the potential for medical applications in anti-adhesion therapy or drug targeting is one of the major driving forces fuelling progress in glycosciences. In histochemistry, this concept has prompted the introduction of carrier-immobilized carbohydrate ligands (neoglycoconjugates) to visualize the cells' capacity to be engaged in oligosaccharide recognition. After their isolation these tissue lectins will be tested for ligand analysis. Since fine specificities of different lectins can differ despite identical monosaccharide binding, the tissue lectins will eventually replace plant agglutinins to move from glycan profiling and localization to functional considerations. Namely, these two marker types, i.e. neoglycoconjugates and tissue lectins, track down accessible binding sites with relevance for involvement in interactions in situ. The documented interplay of synthetic organic chemistry and biochemistry with cyto- and histochemistry nourishes the optimism that the application of this set of innovative custom-prepared tools will provide important insights into the ways in which glycans can act as hardware in transmitting information during normal tissue development and pathological situations.

Apoptosis↗
PubMed1971

Further changes in differentiation state accompanying the conversion of Chinese hamster cells of fibroblastic form by dibutyryl adenosine cyclic 3':5'-monophosphate and hormones.

The morphological conversion in vitro of Chinese hamster ovary cells to a fibroblast form by a relatively large amount of dibutyryl adenosine cyclic 3':5'-monophosphate, or by a combination of small amounts of this compound and testosterone, is attended by appearance of the following additional properties: acquisition of strict contact inhibition of growth; reorientation of the random growth pattern into one in which cells grow parallel to their long dimension; disappearance of the randomly distributed, knob-like, pseudopodal structures around the cell periphery; induction of collagen synthesis; and decrease in the ability to be agglutinated and rounded up by plant agglutinins and specific cell antibodies. The changes in these characteristics are consistent with the conversion from a malignant to a normal fibroblastic state. This conversion is under genetic control, as demonstrated by the production of specific mutants with altered characteristics. The response to testosterone is specific since steroids like estradiol and hydrocortisone are inactive, and others have limited activity. Some prostaglandins are equal in activity to testosterone and 5alpha-dihydrotestosterone. This system appears useful in study of the regulation of phenotypic expression in mammalian cells.

17-Ketosteroids↗
PubMed1972

Distribution of saccharide residues on membrane fragments from a myeloma-cell homogenate: its implications for membrane biogenesis.

Ferritin conjugates of two plant agglutinins, concanavalin A and ricin, have been used as specific electron microscopic stains for covalently-bound saccharide residues on membrane fragments from a myeloma-cell homogenate. The results indicate that different saccharide residues are uniformly localized to a single surface of each membrane fragment. In particular, the ferritin-concanavalin A conjugate binds exclusively to the cisternal side of membrane fragments of the rough endoplasmic reticulum. If it is postulated that the biogenesis of eukaryotic plasma membranes involves an assembly-line process from precursor intracellular membranes, these observed asymmetric distributions of saccharides on cell membranes can be explained.

Animals↗