RESUMO
Interactions between the tumor-associated carbohydrate antigens of Mucin 1 (MUC1) and the carbohydrate-binding proteins, lectins, often lead to the creation of a pro-tumor microenvironment favoring tumor initiation, progression, metastasis, and immune evasion. Macrophage galactose binding lectin (MGL) is a C-type lectin receptor found on antigen-presenting cells that facilitates the uptake of carbohydrate antigens for antigen presentation, modulating the immune response homeostasis, autoimmunity, and cancer. Considering the crucial role of tumor-associated forms of MUC1 and MGL in tumor immunology, a thorough understanding of their binding interaction is essential for it to be exploited for cancer vaccine strategies. The synthesis of MUC1 glycopeptide models carrying a single or multiple Tn and/or sialyl-Tn antigen(s) is described. A novel approach for the sialyl-Tn threonine building block suitable for the solid phase peptide synthesis was developed. The thermodynamic profile of the binding interaction between the human MGL and MUC1 glycopeptide models was analyzed using isothermal titration calorimetry. The measured dissociation constants for the sialyl-Tn-bearing peptide epitopes were consistently lower compared to the Tn antigen and ranged from 10â µM for mono- to 1â µM for triglycosylated MUC1 peptide, respectively. All studied interactions, regardless of the glycan's site of attachment or density, exhibited enthalpy-driven thermodynamics.
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The recruitment of leukocytes from blood is one of the most important cellular processes in response to tissue damage and inflammation. This multi-step process includes rolling leukocytes and their adhesion to endothelial cells (EC), culminating in crossing the EC barrier to reach the inflamed tissue. Galectin-8 and galectin-9 expressed on the immune system cells are part of this process and can induce cell adhesion via binding to oligolactosamine glycans. Similarly, these galectins have an order of magnitude higher affinity towards glycans of the ABH blood group system, widely represented on ECs. However, the roles of gal-8 and gal-9 as mediators of adhesion to endothelial ABH antigens are practically unknown. In this work, we investigated whether H antigen-gal-9-mediated adhesion occurred between Jurkat cells (of lymphocytic origin and known to have gal-9) and EA.hy 926 cells (immortalized endothelial cells and known to have blood group H antigen). Baseline experiments showed that Jurkat cells adhered to EA.hy 926 cells; however when these EA.hy 926 cells were defucosylated (despite the unmasking of lactosamine chains), adherence was abolished. Restoration of fucosylation by insertion of synthetic glycolipids in the form of H (type 2) trisaccharide Fucα1-2Galß1-4GlcNAc restored adhesion. The degree of lymphocyte adhesion to native and the "H-restored" (glycolipid-loaded) EA.hy 926 cells was comparable. If this gal-9/H (type 2) interaction is similar to processes that occur in vivo, this suggests that only the short (trisaccharide) H glycan on ECs is required.
Assuntos
Sistema ABO de Grupos Sanguíneos , Células Endoteliais , Humanos , Galectinas , Glicolipídeos , Células Jurkat , EndotélioRESUMO
Pairing glycans with tissue lectins controls multiple effector pathways in (patho)physiology. A clinically relevant example is the prodegradative activity of galectins-1 and -3 (Gal-1 and -3) in the progression of osteoarthritis (OA) via matrix metalloproteinases (MMPs), especially MMP-13. The design of heterobifunctional inhibitors that can block galectin binding and MMPs both directly and by preventing their galectin-dependent induction selectively offers a perspective to dissect the roles of lectins and proteolytic enzymes. We describe the synthesis of such a reagent with a bivalent galectin ligand connected to an MMP inhibitor and of two tetravalent glycoclusters with a subtle change in headgroup presentation for further elucidation of influence on ligand binding. Testing was performed on clinical material with mixtures of galectins as occurring in vivo, using sections of fixed tissue. Two-colour fluorescence microscopy monitored binding to the cellular glycome after optimization of experimental parameters. In the presence of the inhibitor, galectin binding to OA specimens was significantly reduced. These results open the perspective to examine the inhibitory capacity of custom-made ditopic compounds on binding of lectins in mixtures using sections of clinical material with known impact of galectins and MMPs on disease progression.
RESUMO
Tissue lectins are emerging (patho)physiological effectors with broad significance. The capacity of adhesion/growth-regulatory galectins to form functional complexes with distinct cellular glycoconjugates is based on molecular selection of matching partners. Engineering of variants by changing the topological display of carbohydrate recognition domains (CRDs) provides tools to understand the inherent specificity of the functional pairing. We here illustrate its practical implementation in the case of human tandem-repeat-type galectin-8 (Gal-8). It is termed Gal-8 (NC) due to presence of two different CRDs at the N- and C-terminal positions. Gal-8N exhibits exceptionally high affinity for 3'-sialylated/sulfated ß-galactosides. This protein is turned into a new homodimer, i.e., Gal-8 (NN), by engineering. The product maintained activity for lactose-inhibitable binding of glycans and glycoproteins. Preferential association with 3'-sialylated/sulfated (and 6-sulfated) ß-galactosides was seen by glycan-array analysis when compared to the wild-type protein, which also strongly bound to ABH-type epitopes. Agglutination of erythrocytes documented functional bivalency. This result substantiates the potential for comparative functional studies between the variant and natural Gal-8 (NC)/Gal-8N.
Assuntos
Galectinas/química , Glicoconjugados/química , Animais , Sítios de Ligação , Células CHO , Cricetulus , Galactosídeos/química , Humanos , Polissacarídeos/química , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Sequências de Repetição em Tandem , Termodinâmica , Aderências TeciduaisRESUMO
The emerging significance of recognition of cellular glycans by lectins for diverse aspects of pathophysiology is a strong incentive for considering development of bioactive and non-hydrolyzable glycoside derivatives, for example by introducing S/Se atoms and the disulfide group instead of oxygen into the glycosidic linkage. We report the synthesis of 12 bivalent thio-, disulfido- and selenoglycosides attached to benzene/naphthalene cores. They present galactose, for blocking a plant toxin, or lactose, the canonical ligand of adhesion/growth-regulatory galectins. Modeling reveals unrestrained flexibility and inter-headgroup distances too small to bridge two sites in the same lectin. Inhibitory activity was first detected by solid-phase assays using a surface-presented glycoprotein, with relative activity enhancements per sugar unit relative to free cognate sugar up to nearly 10fold. Inhibitory activity was also seen on lectin binding to surfaces of human carcinoma cells. In order to proceed to characterize this capacity in the tissue context monitoring of lectin binding in the presence of inhibitors was extended to sections of three types of murine organs as models. This procedure proved to be well-suited to determine relative activity levels of the glycocompounds to block binding of the toxin and different human galectins to natural glycoconjugates at different sites in sections. The results on most effective inhibition by two naphthalene-based disulfides and a selenide raise the perspective for broad applicability of the histochemical assay in testing glycoclusters that target biomedically relevant lectins.
Assuntos
Glicosídeos/química , Glicosídeos/farmacologia , Lectinas/antagonistas & inibidores , Animais , Derivados de Benzeno/química , Derivados de Benzeno/farmacologia , Linhagem Celular Tumoral , Dissulfetos/química , Dissulfetos/farmacologia , Humanos , Lectinas/análise , Camundongos Endogâmicos C57BL , Modelos Moleculares , Naftalenos/química , Naftalenos/farmacologia , Compostos Organosselênicos/química , Compostos Organosselênicos/farmacologiaRESUMO
The sequence of a glycan and its topology of presentation team up to determine the specificity and selectivity of recognition by saccharide receptors (lectins). Structure-activity analysis would be furthered if the glycan part of a glycocluster could be efficiently elaborated in situ while keeping all other parameters constant. By using a bacterial α2,6-sialyltransferase and a small library of bi- to tetravalent glycoclusters, we illustrate the complete conversion of scaffold-presented lactoside units into two different sialylated ligands based on N-acetyl/glycolyl-neuraminic acid incorporation. We assess the ensuing effect on their bioactivity for a plant toxin, and present an analysis of the noncovalent substrate binding contacts that the added sialic acid moiety makes to the lectin. Enzymatic diversification of a scaffold-presented glycan can thus be brought to completion in situ, offering a versatile perspective for rational glycocluster engineering.
Assuntos
Polissacarídeos/química , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Cinética , Lectinas/síntese química , Lectinas/química , Lectinas/metabolismo , Ligantes , Espectroscopia de Ressonância Magnética , Simulação de Acoplamento Molecular , Ácidos Neuramínicos/química , Ácidos Neuramínicos/metabolismo , Polissacarídeos/síntese química , Polissacarídeos/metabolismo , Estrutura Terciária de Proteína , Sialiltransferases/metabolismo , Ressonância de Plasmônio de SuperfícieRESUMO
A hallmark of endogenous lectins is their ability to select a few distinct glycoconjugates as counterreceptors for functional pairing from the natural abundance of cellular glycoproteins and glycolipids. As a consequence, assays to assess inhibition of lectin binding should necessarily come as close as possible to the physiological situation, to characterize an impact of a synthetic compound on biorelevant binding with pharmaceutical perspective. We here introduce in a proof-of-principle manner work with sections of paraffin-embedded tissue (jejunum, epididymis) and labeled adhesion/growth-regulatory galectins, harboring one (galectin-1 and galectin-3) or two (galectin-8) types of lectin domain. Six pairs of synthetic lactosides from tailoring of the headgroup (3'-O-sulfation) and the aglycone (ß-methyl to aromatic S- and O-linked extensions) as well as three bi- to tetravalent glycoclusters were used as test compounds. Varying extents of reduction in staining intensity by synthetic compounds relative to unsubstituted/free lactose proved the applicability and sensitivity of the method. Flanking cytofluorimetric assays on lectin binding to native cells gave similar grading, excluding a major impact of tissue fixation. The experiments revealed cell/tissue binding of galectin-8 preferentially via one domain, depending on the cell type so that the effect of an inhibitor in a certain context cannot be extrapolated to other cells/tissues. Moreover, the work with the other galectins attests that this assay enables comprehensive analysis of the galectin network in serial tissue sections to determine overlaps and regional differences in inhibitory profiles.
Assuntos
Galectinas/química , Galectinas/metabolismo , Citometria de Fluxo , Galectinas/classificação , Glicosídeos/síntese química , Glicosídeos/química , Glicosídeos/metabolismo , Humanos , Lectinas/química , Lectinas/metabolismo , Ligação ProteicaRESUMO
Inflammatory chemo- and cytokines and matrix-degrading proteases underlie the progression of osteoarthritis (OA). Aiming to define upstream regulators for these disease markers, we pursued initial evidence for an upregulation of members of the adhesion/growth-regulatory galectin family. Immunohistochemical localization of galectin-3 (Gal-3) in sections of human cartilage with increasing levels of degeneration revealed a linear correlation reaching a chondrocyte positivity of 60%. Presence in situ was cytoplasmic, the lectin was secreted from OA chondrocytes in culture and binding of Gal-3 yielded lactose-inhibitable surface staining. Exposure of cells to the lectin led to enhanced gene expression and secretion of functional disease markers. Genome-wide transcriptomic analysis broadened this result to reveal a pro-degradative/inflammatory gene signature under the control of NF-κB. Fittingly, targeting this route of activation by inhibitors impaired the unfavourable response to Gal-3 binding, as also seen by shortening the lectin's collagen-like repeat region. Gal-3's activation profile overlaps with that of homodimeric galectin-1 (Gal-1) and also has distinctive (supplementing) features. Tested at subsaturating concentrations in a mixture, we found cooperation between the two galectins, apparently able to team up to promote OA pathogenesis. In summary, our results suggest that a network of endogenous lectins is relevant for initiating this process cascade.
Assuntos
Condrócitos/metabolismo , Galectina 1/metabolismo , Galectina 3/metabolismo , Redes Reguladoras de Genes , Osteoartrite/patologia , Idoso , Idoso de 80 Anos ou mais , Proteínas Sanguíneas , Condrócitos/patologia , Matriz Extracelular/metabolismo , Feminino , Galectinas , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Osteoartrite/genética , Osteoartrite/imunologia , Transdução de SinaisRESUMO
Endogenous lectins have the capacity to translate glycan-encoded information on the cell surface into effects on cell growth. As test cases to examine changes in protein presence associated with tumor growth inhibition, we applied SILAC-based proteomics on human colon carcinoma cells treated with galectin-4 (Gal-4). The five tested lines-LS 180, Vaco 432, Colo 205, CX 1, and HCT 116-responded with differentiation and reduced proliferation to Gal-4 binding. In proteomic analysis (mass spectral data deposited with PRIDE, PXD003489), 2654 proteins were quantified, of which 190 were down-regulated and 115 were up-regulated (>2-fold). 1D annotation analysis of the results indicated down-regulation of DNA replication-associated processes, while protein presence for secretory and transport functions appeared increased. The strongest induction was found for CALB2 (calretinin; â¼24-fold), TGM2 (protein-glutamine γ-glutamyltransferase 2; â¼11-fold), S100A3 (â¼10-fold), and GSN (gelsolin; 9.5-fold), and the most pronounced decreases were seen for CDKN2A (tumor suppressor ARF; â¼6-fold), EPCAM (epithelial cell adhesion molecule; â¼6-fold), UBE2C (ubiquitin-conjugating enzyme E2 C; â¼5-fold), KIF2C (kinesin-like protein KIF2C; 5-fold), and LMNB1 (lamin-B1; â¼5-fold). The presence of the common proliferation marker Ki-67 was diminished about 4-fold. By tracing significant alterations of protein expression likely relevant for the observed phenotypic effects, the capacity of a galectin to affect the proteome of human colon cancer cells at multiple sites is revealed.
Assuntos
Membrana Celular/metabolismo , Neoplasias do Colo/metabolismo , Galectina 4/farmacologia , Proteoma/efeitos dos fármacos , Linhagem Celular Tumoral , Neoplasias do Colo/patologia , Galectina 4/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Espectrometria de Massas , Proteoma/análise , Proteômica/métodosRESUMO
The potent multifunctionality of human galectins is based on their modular structure in a not yet fully understood manner. A strategy to dissect the contributions of individual sequence stretches to lectin activity is based on engineering variants of the natural proteins, which are composed of novel combinations of distinct parts. On proof-of-principle level, we here describe the design of a hybrid constituted by the N-terminal tail of chimera-type galectin-3 and the Nterminal carbohydrate recognition domain of tandem-repeat-type galectin-8, its production, purification and its serine phosphorylation characteristic for galectin- 3's tail. As measured for the respective parental proteins, its binding to (neo)glycoproteins is specific for ß-galactosides and inhibitable by lactose, with KD-value closer to galectin-8 than galectin-3. Cell surface staining indicated similarity of the hybrid's reactivity to O-glycans and sensitivity for sialylation to respective properties of tandem-repeattype galectin-8 and its N-terminal domain. Applied as histochemical tool on tissue sections of murine jejunum and epididymis, intense lactose-inhibitable signals were recorded intracellularly, with a distribution profile akin to that of galectin-3. Tested as agglutinin, the hybrid was potent, excelling wild-type control galectins. The chimera-type design can thus serve as platform for tuning crosslinking activity.
Assuntos
Epididimo/metabolismo , Galactosídeos/metabolismo , Galectina 3/metabolismo , Galectinas/metabolismo , Jejuno/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Aglutininas/metabolismo , Animais , Sítios de Ligação/genética , Galectina 3/genética , Galectinas/genética , Humanos , Lactose/química , Masculino , Camundongos , Fosforilação , Ligação Proteica , Proteínas Recombinantes de Fusão/genética , Coloração e Rotulagem , Relação Estrutura-AtividadeRESUMO
BACKGROUND: Galectin-related protein (GRP), present in vertebrates, is special within this family of adhesion/growth-regulatory proteins due to its strong positive selection and loss of canonical lectin activity. METHODS: RT-PCR and Western blotting together with flow cytofluorimetry and immunocyto- and histochemistry monitor expression and localization of chicken GRP. The promoter sequence of the GRP gene is processed computationally to detect putative sites for binding transcription factors. The labeled protein is applied as probe to detect binding sites on cells and in sections, along with glycocompounds to test inhibition of the association. RESULTS: Expression of GRP in chicken is limited to bursa of Fabricius, immunohistochemically found in B cells, also in bursal epithelium and vessels. Presence in B cells is shared with only one canonical galectin, i.e. CG-8. Binding to a chicken lymphoma line was specific and saturable, not affected by lactose but completely blocked by heparin, as also seen in sections. CONCLUSIONS: Expression monitoring initiated for GRP reveals a distinct site of localization in chicken, much more restricted than for any of its canonical galectins.
Assuntos
Galinhas/genética , Galectinas/biossíntese , Regulação da Expressão Gênica/genética , Sequência de Aminoácidos/genética , Animais , Linfócitos B/imunologia , Linfócitos B/metabolismo , Sítios de Ligação , Galinhas/imunologia , Galectinas/genética , Galectinas/metabolismo , Perfilação da Expressão Gênica , Ligantes , Especificidade de Órgãos , Regiões Promotoras Genéticas , Ligação ProteicaRESUMO
Occurrence of the adhesion/growth-regulatory galectins as family sets the challenge to achieve a complete network analysis. Along this route taken for a well-suited model organism (chicken), we fill the remaining gap to characterize its seventh member known from rat as galectin-related inter-fiber protein (GRIFIN) in the lens. Its single-copy gene is common to vertebrates, with one or more deviations from the so-called signature sequence for ligand (lactose) contact. The chicken protein is a homodimeric agglutinin with capacity to bind ß-galactosides, especially the histo-blood group B tetrasaccharide, shown by solid-phase/cell assays and a glycan microarray. Mass spectrometric identification of two lactose-binding peptides after tryptic on-bead fragmentation suggests an interaction at the canonical region despite a sequence change from Arg to Val at the site, which impairs reactivity of human galectin-1. RT-PCR and Western blot analyses of specimen from adult chicken organs reveal restriction of expression to the lens, here immunohistochemically throughout its main body. This report sets the stage for detailed structure-activity studies to define factors relevant for affinity beyond the signature sequence and to perform the first complete network analysis of the galectin family in developing and adult organs of a vertebrate.
Assuntos
Proteínas Aviárias/genética , Proteínas do Olho/genética , Galectinas/genética , Perfilação da Expressão Gênica/métodos , Redes Reguladoras de Genes , Sequência de Aminoácidos , Animais , Proteínas Aviárias/química , Proteínas Aviárias/metabolismo , Sítios de Ligação/genética , Western Blotting , Galinhas , Proteínas do Olho/classificação , Proteínas do Olho/metabolismo , Galectinas/classificação , Galectinas/metabolismo , Humanos , Imuno-Histoquímica , Lactose/metabolismo , Cristalino/metabolismo , Filogenia , Ligação Proteica , Multimerização Proteica , Ratos , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de AminoácidosRESUMO
Multiple myeloma is characterized by abnormal infiltration of malignant plasma cells into bone marrow. Testing the hypothesis that bivalent galectin-8 (Gal-8) may influence homing of myeloma cells to vascular endothelium as a key prerequisite for infiltration, we analyzed the two Gal-8 splice variants (Gal-8S, Gal-8L). They differ in the length of their linker peptide connecting the two lectin domains. Both Gal-8 isoforms bind to cells of the myeloma lines Gal-8+ MOLP-8 and Gal-8- LP-1 in a glycan-inhibitable manner. Both Gal-8 isoforms led to enhanced adhesion of myeloma cells to vascular endothelium under dynamic shear stress conditions, Gal-8L (by more than 40-fold) even stronger than Gal-8S. Additional treatment of endothelial cells with tumour necrosis factor prior to the dynamic shear stress assay entailed an almost 100-fold enhanced adhesion of myeloma cells without addition of Gal-8 variants and a further 1.5-1.7-fold enhancement by addition of Gal-8 variants. We also found that elevated expression of Gal-8 in native multiple myeloma cells is an adverse prognostic factor for overall and event-free survival using patients' gene expression profile data of the total therapy 2 and 3 myeloma studies. Also, elevated concentrations of Gal-8 were detected (45%, 19/42 patients) in sera of multiple myeloma patients compared to those of healthy, age-matched donors. Both experimental and clinical data strongly point to the significance of Gal-8 for multiple myeloma development.
Assuntos
Endotélio Vascular/metabolismo , Galectinas/metabolismo , Mieloma Múltiplo/metabolismo , Adesão Celular , Células Cultivadas , Humanos , Mieloma Múltiplo/diagnóstico , Proteínas Recombinantes/metabolismoRESUMO
Galectin-3 is an adhesion/growth-regulatory protein with a modular design comprising an N-terminal tail (NT, residues 1-111) and the conserved carbohydrate recognition domain (CRD, residues 112-250). The chimera-type galectin interacts with both glycan and peptide motifs. Complete (13)C/(15)N-assignment of the human protein makes NMR-based analysis of its structure beyond the CRD possible. Using two synthetic NT polypeptides covering residues 1-50 and 51-107, evidence for transient secondary structure was found with helical conformation from residues 5 to 15 as well as proline-mediated, multi-turn structure from residues 18 to 32 and around PGAYP repeats. Intramolecular interactions occur between the CRD F-face (the 5-stranded ß-sheet behind the canonical carbohydrate-binding 6-stranded ß-sheet of the S-face) and NT in full-length galectin-3, with the sequence P(23)GAW(26) P(37)GASYPGAY(45) defining the primary binding epitope within the NT. Work with designed peptides indicates that the PGAX motif is crucial for self-interactions between NT/CRD. Phosphorylation at position Ser6 (and Ser12) (a physiological modification) and the influence of ligand binding have minimal effect on this interaction. Finally, galectin-3 molecules can interact weakly with each other via the F-faces of their CRDs, an interaction that appears to be assisted by their NTs. Overall, our results add insight to defining binding sites on galectin-3 beyond the canonical contact area for ß-galactosides.
Assuntos
Galectina 3/química , Peptídeos/química , Sequência de Aminoácidos , Sítios de Ligação , Proteínas Sanguíneas , Isótopos de Carbono/química , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Galectina 3/genética , Galectina 3/metabolismo , Galectinas , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Humanos , Modelos Moleculares , Isótopos de Nitrogênio/química , Ressonância Magnética Nuclear Biomolecular , Peptídeos/síntese química , Peptídeos/metabolismo , Fosforilação , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de SequênciaRESUMO
A library of amphiphilic Janus dendrimers including two that are fluorescent and one glycodendrimer presenting lactose were used to construct giant dendrimersomes and glycodendrimersomes. Coassembly with the components of bacterial membrane vesicles by a dehydration-rehydration process generated giant cell-like hybrid vesicles, whereas the injection of their ethanol solution into PBS produced monodisperse nanometer size assemblies. These hybrid vesicles contain transmembrane proteins including a small membrane protein, MgrB, tagged with a red fluorescent protein, lipopolysaccharides, and glycoproteins from the bacterium Escherichia coli. Incorporation of two colored fluorescent probes in each of the components allowed fluorescence microscopy to visualize and demonstrate coassembly and the incorporation of functional membrane channels. Importantly, the hybrid vesicles bind a human galectin, consistent with the display of sugar moieties from lipopolysaccharides or possibly glycosylated membrane proteins. The present coassembly method is likely to create cell-like hybrids from any biological membrane including human cells and thus may enable practical application in nanomedicine.
Assuntos
Parede Celular/metabolismo , Dendrímeros/metabolismo , Escherichia coli/metabolismoRESUMO
Osteoarthritis is a degenerative joint disease that ranks among the leading causes of adult disability. Mechanisms underlying osteoarthritis pathogenesis are not yet fully elucidated, putting limits to current disease management and treatment. Based on the phenomenological evidence for dysregulation within the glycome of chondrocytes and the network of a family of adhesion/growth-regulatory lectins, that is, galectins, we tested the hypothesis that Galectin-1 is relevant for causing degeneration. Immunohistochemical analysis substantiated that Galectin-1 upregulation is associated with osteoarthritic cartilage and subchondral bone histopathology and severity of degeneration (p < 0.0001, n = 29 patients). In vitro, the lectin was secreted and it bound to osteoarthritic chondrocytes inhibitable by cognate sugar. Glycan-dependent Galectin-1 binding induced a set of disease markers, including matrix metalloproteinases and activated NF-κB, hereby switching on an inflammatory gene signature (p < 10(-16)). Inhibition of distinct components of the NF-κB pathway using dedicated inhibitors led to dose-dependent impairment of Galectin-1-mediated transcriptional activation. Enhanced secretion of effectors of degeneration such as three matrix metalloproteinases underscores the data's pathophysiological relevance. This study thus identifies Galectin-1 as a master regulator of clinically relevant inflammatory-response genes, working via NF-κB. Because inflammation is critical to cartilage degeneration in osteoarthritis, this report reveals an intimate relation of glycobiology to osteoarthritic cartilage degeneration.
Assuntos
Galectina 1/metabolismo , Regulação da Expressão Gênica/fisiologia , Redes Reguladoras de Genes/fisiologia , NF-kappa B/metabolismo , Osteoartrite/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Western Blotting , Cartilagem Articular/metabolismo , Cartilagem Articular/patologia , Condrócitos/metabolismo , Ensaio de Imunoadsorção Enzimática , Feminino , Imunofluorescência , Glicômica , Humanos , Imuno-Histoquímica , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Osteoartrite/genética , Osteoartrite/patologia , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
A library of eight amphiphilic Janus glycodendrimers (GDs) with d-mannose (Man) headgroups, a known routing signal for lectin-mediated transport processes, was constructed via an iterative modular methodology. Sequence-defined variations of the Janus GD modulate the surface density and sequence of Man after self-assembly into multilamellar glycodendrimersomes (GDSs). The spatial mode of Man presentation is decisive for formation of either unilamellar or onion-like GDS vesicles. Man presentation and Janus GD concentration determine GDS size and number of bilayers. Beyond vesicle architecture, Man topological display affects kinetics and plateau level of GDS aggregation by a tetravalent model lectin: the leguminous agglutinin Con A, which is structurally related to endogenous cargo transporters. The agglutination process was rapid, efficient, and readily reversible for onion-like GDSs, demonstrating their value as versatile tools to explore the nature of physiologically relevant glycan/lectin pairing.
Assuntos
Carboidratos/química , Dendrímeros/química , Lectinas/química , Microscopia Eletrônica de TransmissãoRESUMO
Nonlamellar lipid arrangements, including cubosomes, appear in unhealthy cells, e.g., when they are subject to stress, starvation, or viral infection. The bioactivity of cubosomes-nanoscale particles exhibiting bicontinuous cubic structures-versus more common vesicles is an unexplored area due to lack of suitable model systems. Here, glycodendrimercubosomes (GDCs)-sugar-presenting cubosomes assembled from Janus glycodendrimers by simple injection into buffer-are proposed as mimics of biological cubic membranes. The bicontinuous cubic GDC architecture has been demonstrated by electron tomography. The stability of these GDCs in buffer enabled studies on lectin-dependent agglutination, revealing significant differences compared with the vesicular glycodendrimersome (GDS) counterpart. In particular, GDCs showed an increased activity toward concanavalin A, as well as an increased sensitivity and selectivity toward two variants of banana lectins, a wild-type and a genetically modified variant, which is not exhibited by GDSs. These results suggest that cells may adapt under unhealthy conditions by undergoing a transformation from lamellar to cubic membranes as a method of defense.
RESUMO
Estrogen deprivation is considered responsible for many age-related processes, including poor wound healing. Guided by previous observations that estradiol accelerates reepithelialization through estrogen receptor (ER)ß, in the present study, we examined whether selective ER agonists [4,4',4''-(4-propyl [1H] pyrazole-1,3,5-triyl)trisphenol (PPT), ERα agonist; 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), ERß agonist] affect the expression of basic proliferation and differentiation markers (Ki67, keratin10, 14 and 19, galectin1 and Sox2) of keratinocytes using HaCaT cells. In parallel, ovariectomized rats were treated daily with an ER modulator, and wound tissue was removed 21 days after wounding and routinely processed for basic histological analysis. Our results revealed that the HaCaT keratinocytes expressed both ERα and ß, and thus are well-suited for studying the effects of ER agonists on epidermal regeneration. The activation of ERα produced a protein expression pattern similar to that observed in the control culture, with a moderate expression of Ki67 being observed. However, the activation of ERß led to an increase in cell proliferation and keratin19 expression, as well as a decrease in galectin1 expression. Fittingly, in rat wounds treated with the ERß agonist (DPN), epidermal regeneration was accelerated. In the present study, we provide information on the mechanisms through which estrogens affect the expression patterns of selected markers, thus modulating keratinocyte proliferation and differentiation; in addition, we demonstrate that the pharmacological activation of ER-α and -ß has a direct impact on wound healing.