Galectins are carbohydrate-binding lectins that modulate the proliferation, apoptosis, adhesion, or migration of cells by cross-linking glycans on cell membranes or extracellular matrix components. Galectin-4 (Gal-4) is a tandem-repeat-type galectin expressed mainly in the epithelial cells of the gastrointestinal tract. It consists of an N- and a C-terminal carbohydrate-binding domain (CRD), each with distinct binding affinities, interconnected with a peptide linker. Compared to other more abundant galectins, the knowledge of the pathophysiology of Gal-4 is sparse. Its altered expression in tumor tissue is associated with, for example, colon, colorectal, and liver cancers, and it increases in tumor progression, and metastasis. There is also very limited information on the preferences of Gal-4 for its carbohydrate ligands, particularly with respect to Gal-4 subunits. Similarly, there is virtually no information on the interaction of Gal-4 with multivalent ligands. This work shows the expression and purification of Gal-4 and its subunits and presents a structure-affinity relationship study with a library of oligosaccharide ligands. Furthermore, the influence of multivalency is demonstrated in the interaction with a model lactosyl-decorated synthetic glycoconjugate. The present data may be used in biomedical research for the design of efficient ligands of Gal-4 with diagnostic or therapeutic potential.
Galectins are lectins that bind β-galactosides. They are involved in important extra- and intracellular biological processes such as apoptosis, and regulation of the immune system or the cell cycle. High-affinity ligands of galectins may introduce new therapeutic approaches or become new tools for biomedical research. One way of increasing the low affinity of β-galactoside ligands to galectins is their multivalent presentation, e.g., using calixarenes. We report on the synthesis of glycocalix[4]arenes in cone, partial cone, 1,2-alternate, and 1,3-alternate conformations carrying a lactosyl ligand on three different linkers. The affinity of the prepared compounds to a library of human galectins was determined using competitive ELISA assay and biolayer interferometry. Structure-affinity relationships regarding the influence of the linker and the core structure were formulated. Substantial differences were found between various linker lengths and the position of the triazole unit. The formation of supramolecular clusters was detected by atomic force microscopy. The present work gives a systematic insight into prospective galectin ligands based on the calix[4]arene core.
- MeSH
- galektiny * chemie MeSH
- glykokalyx * MeSH
- lidé MeSH
- ligandy MeSH
- molekulární konformace MeSH
- prospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Lectins, a distinct group of glycan-binding proteins, play a prominent role in the immune system ranging from pathogen recognition and tuning of inflammation to cell adhesion or cellular signalling. The possibilities of their detailed study expanded along with the rapid development of biomaterials in the last decade. The immense knowledge of all aspects of glycan-lectin interactions both in vitro and in vivo may be efficiently used in bioimaging, targeted drug delivery, diagnostic and analytic biological methods. Practically applicable examples comprise photoluminescence and optical biosensors, ingenious three-dimensional carbohydrate microarrays for high-throughput screening, matrices for magnetic resonance imaging, targeted hyperthermal treatment of cancer tissues, selective inhibitors of bacterial toxins and pathogen-recognising lectin receptors, and many others. This review aims to present an up-to-date systematic overview of glycan-decorated biomaterials promising for interactions with lectins, especially those applicable in biology, biotechnology or medicine. The lectins of interest include galectin-1, -3 and -7 participating in tumour progression, bacterial lectins from Pseudomonas aeruginosa (PA-IL), E. coli (Fim-H) and Clostridium botulinum (HA33) or DC-SIGN, receptors of macrophages and dendritic cells. The spectrum of lectin-binding biomaterials covered herein ranges from glycosylated organic structures, calixarene and fullerene cores over glycopeptides and glycoproteins, functionalised carbohydrate scaffolds of cyclodextrin or chitin to self-assembling glycopolymer clusters, gels, micelles and liposomes. Glyconanoparticles, glycan arrays, and other biomaterials with a solid core are described in detail, including inorganic matrices like hydroxyapatite or stainless steel for bioimplants.
- MeSH
- Bacteria chemie MeSH
- biokompatibilní materiály chemie normy MeSH
- cukry chemie MeSH
- galektiny chemie metabolismus MeSH
- lektiny typu C chemie metabolismus MeSH
- lektiny chemie metabolismus MeSH
- molekuly buněčné adheze metabolismus MeSH
- receptory buněčného povrchu metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Carbohydrates represent a fundamental building unit of living organisms. Many contemporary results introduce these substances as medium with remarkable data storage capacity (glycocode) that is decoded by special receptor counterpartners, lectins. Animal so-called endogenous lectins are presented here as the biotinylated tools for normal lectin histochemistry in accompany with biotinylated (neo)glycoconjugates employed in reverse lectin histochemistry. Practical lesson how to employ these probes in cell/tissue labeling including multiple cell labeling at the single-cell level is also included. Position of glycocode and endogenous lectins in squamous epithelium biology under physiological condition and after the malignant transformation is shown as example of the employment of mentioned probes in research and diagnostics.
Following the detection of individual members of the family of galectins it is an obvious challenge to define the extent of functional overlap/divergence among these proteins. As a step to address this issue a comparative profiling has been started in the mouse as a model organism, combining sequence analysis, expression patterns and structural features in the cases of the homodimeric galectins-1, -2 and -7. Close relationship was apparent at the level of global gene organization. Scrutiny of the proximal promoter regions for putative transcription-factor-binding sites by two search algorithms uncovered qualitative and quantitative differences with potential to influence the combinatorial functionality of regulatory sequences. RT-PCR mapping with samples from an array of 17 organs revealed significant differences, separating rather ubiquitous gene expression of galectin-1 from the more restricted individual patterns of galectins-2 and -7. Using specific antisera obtained by affinity depletion including stringent controls to ascertain lack of cross-reactivity these results were corroborated at the level of galectin localization in fixed tissue sections. Nuclear presence was seen in the case of galectin-1. In addition to nonidentical expression profiles the mapping of the carbohydrate recognition domains of galectins-1 and -7 by homology modelling and docking of naturally occurring complex tetra- and pentasaccharides disclosed a series of sequence deviations which may underlie disparate affinities for cell surface glycans/glycomimetic peptides. In view of applicability the presented data can serve as useful reference to delineate changes with respect to disease and in genetically engineered models. To enable more general conclusions on the galectin network it is warranted to further pursue this combined approach within this lectin family.
- MeSH
- databáze nukleových kyselin MeSH
- dimerizace MeSH
- finanční podpora výzkumu jako téma MeSH
- galektiny genetika chemie metabolismus MeSH
- imunohistochemie MeSH
- konformace sacharidů MeSH
- ligandy MeSH
- myši MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- regulace genové exprese MeSH
- sacharidy chemie MeSH
- sekvence aminokyselin MeSH
- transkripční faktory metabolismus MeSH
- vazebná místa MeSH
- výpočetní biologie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
Galectin-4 and its homologue galectin-6 are members of the tandem-repeat subfamily of monomer divalent galectins. Expression of mouse galectin-4 and galectin-6 by RT-PCR using primers designed to distinguish both galectin transcripts indicates that both are expressed in the small intestine, colon, liver, kidney, spleen and heart and P19X1 cells while only galectin-4 is expressed in BW-5147 and 3T3 cell lines. In situ hybridization confirmed the presence of galectin-4/-6 transcripts in the liver and small intestine. Galectin-4 is expressed in spermatozoons and oocytes and its expression during early mouse emryogenesis appears in 8-cell embryos and remains in later stages, as tested by RT-PCR. To study the role of carbohydrate recognition domains (CRDs) in oligosaccharide binding and epitope recognition, we cloned mouse full-length galectin-4 and galectin-6 cDNA and constructed bacterial expression vectors producing histidin-tagged recombinant galectin-4 and its truncated CRD1 and CRD2 forms. Oligosaccharide binding profile for all recombinant forms was assessed using Glycan Array available through the Consortium for Functional Glycomics. Acquired data indicate that mGalectin-4 binds to alpha-GalNAc and alpha-Gal A and B type structures with or without fucose. While the CRD2 domain has a high specificity and affinity for A type-2 alpha-GalNAc structures, the CRD1 domain has a broader specificity in correlation to the total binding profile. These data suggest that CRD2 might be the dominant binding domain of mouse galectin-4. Mapping of epitopes reactive for biotinylated his-tagged CRD1, CRD2 and mGalectin-4 performed on mouse cryosections showed that all three forms bind to alveolar macrophages, macrophages of red pulp of the spleen and proximal tubuli of the kidney and this binding was inhibited by 5 mM lactose. Interestingly, mGalectin-4, but not CRD forms, binds to the suprabasal layer of squamous epithelium of the tongue, suggesting that the link region also plays an important role in ligand recognition.
- MeSH
- buňky 3T3 MeSH
- epitopy chemie metabolismus MeSH
- financování organizované MeSH
- galektin 4 genetika chemie MeSH
- galektiny genetika chemie MeSH
- hybridizace in situ metody MeSH
- imunohistochemie MeSH
- komplementární DNA genetika MeSH
- molekulární sekvence - údaje MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nádorové buněčné linie MeSH
- oligosacharidy chemie metabolismus MeSH
- rekombinantní proteiny biosyntéza chemie MeSH
- sacharidové sekvence MeSH
- stanovení celkové genové exprese MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
