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Sialic acid is a unique sugar moiety that resides in the distal and most accessible position of the glycans on mammalian cell surface and extracellular glycoproteins and glycolipids. The potential for sialic acid to obscure underlying structures has long been postulated, but the means by which such structural changes directly affect biological processes continues to be elucidated. Here, we appraise the growing body of literature detailing the importance of sialic acid for the generation, differentiation, function and death of haematopoietic cells. We conclude that sialylation is a critical post‐translational modification utilized in haematopoiesis to meet the dynamic needs of the organism by enforcing rapid changes in availability of lineage‐specific cell types. Though long thought to be generated only cell‐autonomously within the intracellular ER‐Golgi secretory apparatus, emerging data also demonstrate previously unexpected diversity in the mechanisms of sialylation. Emphasis is afforded to the mechanism of extrinsic sialylation, whereby extracellular enzymes remodel cell surface and extracellular glycans, supported by charged sugar donor molecules from activated platelets. [ABSTRACT FROM AUTHOR]

BACKGROUND: Galectins (GALs) are a family of mammalian sugar‐binding proteins specific for β‐galactosides. Our previous studies have shown that the larval development of the diamondback moth (Plutella xylostella) is significantly disturbed when fed with recombinant mammalian galectin 1 (GAL1) derived from Escherichia coli. To further explore its applicability, two GAL1‐overexpressed Arabidopsis [GAL1‐Arabidopsis (whole plant) and GAL1‐Arabidopsis‐vas (vascular bundle‐specific)] lines were established for insecticidal activity and mechanism studies. RESULTS: The expression level of GAL1 in transgenic Arabidopsis is 1–0.5% (GAL1‐Arabidopsis) and 0.08–0.01% (GAL1‐Arabidopsis‐vas) of total leaf soluble protein. Survival, body weight, and food consumption significantly decreased in a time‐dependent manner in P. xylostella larvae (with chewing mouthparts) fed on GAL1‐Arabidopsis. The mortality of Kolla paulula (with piercing‐sucking mouthparts and xylem feeder) fed on GAL1‐Arabidopsis‐vas was also significantly higher than that fed on wild‐type Arabidopsis (WT‐Arabidopsis), but was lower than that fed on GAL1‐Arabidopsis. The histochemical structure and results of immunostaining suggested that the binding of GAL1 to the midgut epithelium of P. xylostella fed on GAL1‐Arabidopsis was dose‐ and time‐dependent. Ultrastructural studies further showed the disruption of microvilli, abnormalities in epithelial cells, and fragments of the peritrophic membrane (PM) in P. xylostella larvae fed on GAL1‐Arabidopsis. CONCLUSION: The insecticidal mechanism of GAL1 involves interference with PM integrity and suggests that GAL1 is a potential candidate for bioinsecticide development. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Recent advances in the field demonstrate the high diversity and complexity of endocytic pathways. In the current study, we focus on the endocytosis of L1CAM. This glycoprotein plays a major role in the development of the nervous system, and is involved in cancer development and is associated with metastases and poor prognosis. Two L1CAM isoforms are subject to endocytosis: isoform 1, described as a clathrin‐mediated cargo; isoform 2, whose endocytosis has never been studied. Deciphering the molecular machinery of isoform 2 internalisation should contribute to a better understanding of its pathophysiological role. First, we demonstrated in our cellular context that both isoforms of L1CAM are mainly a clathrin‐independent cargo, which was not expected for isoform 1. Second, the mechanism of L1CAM endocytosis is specifically mediated by the N‐BAR domain protein endophilin‐A3. Third, we discovered PSTPIP1, an F‐BAR domain protein, as a novel actor in this endocytic process. Finally, we identified galectins as endocytic partners and negative regulators of L1CAM endocytosis. In summary, the interplay of the BAR proteins endophilin‐A3 and PSTPIP1, and galectins fine tune the clathrin‐independent endocytosis of L1CAM. [ABSTRACT FROM AUTHOR]

Aims: Low cardiorespiratory fitness (CRF) is associated with greater mortality and morbidity. Galectin‐3 (Gal‐3) is a prognostic biomarker for fibrosis and heart failure. Gal‐3 is also associated with a greater risk for cardiovascular mortality. Whether CRF is related with Gal‐3 is unclear. The objective of this study was to assess the sex‐specific associations of CRF and Gal‐3 levels in the general population. Methods: Gal‐3 concentrations were determined using a sandwich enzyme immunoassay in the population‐based Study of Health in Pomerania (SHIP‐TREND‐0). Sex‐stratified linear regression models adjusted for age, current smoking status, and renal function were used. Individuals with left ventricular ejection fraction (LVEF) <40%, previous myocardial infarction, atrial fibrillation, chronic lung disease, severe renal disease (estimated glomerular filtration rate <30 mL/min/mm2), a history of cancer, and extreme values for Gal‐3 (<1st percentile; >99th percentile) were excluded. Results: A total of n = 1515 participants with a median age of 49 (IQR: 39–60 years, 48% males) were included. In men, a 1 L/min greater VO2peak was significantly related to 0.50 ng/mL (95% CI −0.8068 to −0.1938, P < 0.01) less Gal‐3. In males, a 1 mL/min/kg higher VO2peak adjusted for body weight was associated with −0.0286 ng/mL (95% CI −0.0052 to −0.0005, P = 0.02) less Gal‐3. When VO2peak was adjusted for lean mass 1 mL/kg/min more was correlated with a −0.0022 ng/mL (95% CI −0.0043 to ‐0.0007, P = 0.04) less Gal‐3. In women, VO2peak (β −0.2046 95% CI −0.6541 to 0.2449, P = 0.37) and VO2peak adjusted for lean mass (β −0.0019 95% CI −0.0421 to –0.0050, P = 0.12) were not related with Gal‐3, whereas a 1 mL/min/kg higher VO2peak adjusted for body weight was significantly associated with a −0.0064 ng/mL lower Gal‐3 (95% CI −0.0092 to ‐0.0035, P < 0.01). There were no differences between pre‐menopausal and post‐menopausal women. Conclusions: VO2peak was associated with Gal‐3 only in men, but VO2peak adjusted for body weight in women and men. Our results suggest that the adverse consequences of low CRF may be mediated by Gal‐3. Further research is needed to understand the sex‐specific association between CRF and Gal‐3 and whether they are clinically relevant. [ABSTRACT FROM AUTHOR]

We previously observed that genomic loss of galectin‐3 (Gal‐3; encoded by Lgals3) in mice has a significant protective effect on age‐related bone loss. Gal‐3 has both intracellular and extracellular functionality, and we wanted to assess whether the affect we observed in the Lgals3 knockout (KO) mice could be attributed to the ability of Gal‐3 to bind glycoproteins. Mutation of a highly conserved arginine to a serine in human Gal‐3 (LGALS3‐R186S) blocks glycan binding and secretion. We generated mice with the equivalent mutation (Lgals3‐R200S) and observed a subsequent reduction in Gal‐3 secretion from mouse embryonic fibroblasts and in circulating blood. When examining bone structure in aged mice, we noticed some similarities to the Lgals3‐KO mice and some differences. First, we observed greater bone mass in Lgals3‐R200S mutant mice, as was previously observed in Lgals3‐KO mice. Like Lgals3‐KO mice, significantly increased trabecular bone mass was only observed in female Lgals3‐R200S mice. These results suggest that the greater bone mass observed is driven by the loss of extracellular Gal‐3 functionality. However, the results from our cortical bone expansion data showed a sex‐dependent difference, with only male Lgals3‐KO mice having an increased response, contrasting with our earlier study. These notable sex differences suggest a potential role for sex hormones, most likely androgen signaling, being involved. In summary, our results suggest that targeting extracellular Gal‐3 function may be a suitable treatment for age‐related loss of bone mass. [ABSTRACT FROM AUTHOR]

Breast cancer cells release a large quantity of biocargo‐bearing extracellular vesicles (EVs), which mediate intercellular communication within the tumour microenvironment and promote metastasis. To identify EV‐bound proteins related to metastasis, we used mass spectrometry to profile EVs from highly and poorly metastatic breast cancer lines of human and mouse origins. Comparative mass spectrometry indicated that integrins, including αv and β1 subunits, are preferentially enriched in EVs of highly metastatic origin over those of poorly metastatic origin. These results are consistent with our histopathological findings, which show that integrin αv is associated with disease progression in breast cancer patients. Integrin αv colocalizes with the multivesicular‐body marker CD63 at a higher frequency in the tumour and is enriched in circulating EVs of breast cancer patients at late stages when compared with circulating EVs from early‐stage patients. With a magnetic bead‐based flow cytometry assay, we confirmed that integrins αv and β1 are enriched in the CD63+ subsets of EVs from both human and mouse highly metastatic cells. By analysing the level of integrin αv on circulating EVs, this assay could predict the metastatic potential of a xenografted mouse model. To explore the export mechanism of integrins into EVs, we performed immunoprecipitation mass spectrometry and identified members of the galectin family as potential shuttlers of integrin αvβ1 into EVs. In particular, knockdown of galectin‐3, but not galectin‐1, causes a reduction in the levels of cell surface integrins β1 and αv, and decreases the colocalization of these integrins with CD63. Importantly, knockdown of galectin‐3 leads to a decrease of integrin αvβ1 export into the EVs concomitant with a decrease in the metastatic potential of breast cancer cells. Moreover, inhibition of the integrin αvβ1 complex leads to a reduction in the binding of EVs to fibronectin, suggesting that integrin αvβ1 is important for EV retention in the extracellular matrix. EVs retained in the extracellular matrix are taken up by fibroblasts, which differentiate into cancer associated fibroblasts. In summary, our data indicate an important link between EV‐bound integrin αvβ1 with breast cancer metastasis and provide additional insights into the export of integrin αvβ1 into EVs in the context of metastasis. [ABSTRACT FROM AUTHOR]

Symbiotic microbes play a crucial role in regulating parasite–host interactions; however, the role of bacterial associates in parasite–host interactions requires elucidation. In this study, we showed that, instead of introducing numerous symbiotic bacteria, dispersal of 4th‐stage juvenile (JIV) pinewood nematodes (PWNs), Bursaphelenchus xylophilus, only introduced few bacteria to its vector beetle, Monochamus alternatus (Ma). JIV showed weak binding ability to five dominant bacteria species isolated from the beetles' pupal chamber. This was especially the case for binding to the opportunistic pathogenic species Serratia marcescens; the nematodes' bacteria binding ability at this critical stage when it infiltrates Ma for dispersal was much weaker compared with Caenorhabditis elegans, Diplogasteroides asiaticus, and propagative‐stage PWN. The associated bacterium S. marcescens, which was isolated from the beetles' pupal chambers, was unfavorable to Ma, because it caused a higher mortality rate upon injection into tracheae. In addition, S. marcescens in the tracheae caused more immune effector disorders compared with PWN alone. Ma_Galectin2 (MaGal2), a pattern‐recognition receptor, was up‐regulated following PWN loading. Recombinant MaGal2 protein formed aggregates with five dominant associated bacteria in vitro. Moreover, MaGal2 knockdown beetles had up‐regulated prophenoloxidase gene expression, increased phenoloxidase activity, and decreased PWN loading. Our study revealed a previously unknown strategy for immune evasion of this plant pathogen inside its vector, and provides novel insights into the role of bacteria in parasite–host interactions. [ABSTRACT FROM AUTHOR]

The interaction of human galectin‐1 with a variety of oligosaccharides, from di‐(N‐acetyllactosamine) to tetra‐saccharides (blood B type‐II antigen) has been scrutinized by using a combined approach of different NMR experiments, molecular dynamics (MD) simulations, and isothermal titration calorimetry. Ligand‐ and receptor‐based NMR experiments assisted by computational methods allowed proposing three‐dimensional structures for the different complexes, which explained the lack of enthalpy gain when increasing the chemical complexity of the glycan. Interestingly, and independently of the glycan ligand, the entropy term does not oppose the binding event, a rather unusual feature for protein‐sugar interactions. CLEANEX‐PM and relaxation dispersion experiments revealed that sugar binding affected residues far from the binding site and described significant changes in the dynamics of the protein. In particular, motions in the microsecond‐millisecond timescale in residues at the protein dimer interface were identified in the presence of high affinity ligands. The dynamic process was further explored by extensive MD simulations, which provided additional support for the existence of allostery in glycan recognition by human galectin‐1. [ABSTRACT FROM AUTHOR]

Human γδ T lymphocytes are predominated by two major subsets, defined by the variable domain of the δ chain. Both, Vδ1 and Vδ2 T cells infiltrate in tumors and have been implicated in cancer immunosurveillance. Since the localization and distribution of tumor‐infiltrating γδ T cell subsets and their impact on survival of cancer patients are not completely defined, this review summarizes the current knowledge about this issue. Different intrinsic tumor resistance mechanisms and immunosuppressive molecules of immune cells in the tumor microenvironment have been reported to negatively influence functional properties of γδ T cell subsets. Here, we focus on selected tumor resistance mechanisms including overexpression of cyclooxygenase (COX)‐2 and indolamine‐2,3‐dioxygenase (IDO)‐1/2, regulation by tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL)/TRAIL‐R4 pathway and the release of galectins. These inhibitory mechanisms play important roles in the cross‐talk of γδ T cell subsets and tumor cells, thereby influencing cytotoxicity or proliferation of γδ T cells and limiting a successful γδ T cell‐based immunotherapy. Possible future directions of a combined therapy of adoptively transferred γδ T cells together with γδ‐targeting bispecific T cell engagers and COX‐2 or IDO‐1/2 inhibitors or targeting sialoglycan‐Siglec pathways will be discussed and considered as attractive therapeutic options to overcome the immunosuppressive tumor microenvironment. [ABSTRACT FROM AUTHOR]

Galectins play key roles in numerous biological processes. Their mode of action depends on their localization which can be extracellular, cytoplasmic, or nuclear and is partly mediated through interactions with β‐galactose containing glycans. Galectins have emerged as novel therapeutic targets notably for the treatment of inflammatory disorders and cancers. This has stimulated the design of carbohydrate‐based inhibitors targeting the carbohydrate recognition domains (CRDs) of the galectins. Pursuing this approach, we reasoned that linear oligogalactosides obtained by straightforward iterative click chemistry could mimic poly‐lactosamine motifs expressed at eukaryote cell surfaces which the extracellular form of galectin‐3, a prominent member of the galectin family, specifically recognizes. Affinities toward galectin‐3 consistently increased with the length of the representative oligogalactosides but without reaching that of oligo‐lactosamines. Elucidation of the X‐ray crystal structures of the galectin‐3 CRD in complex with a synthesized di‐ and tri‐galactoside confirmed that the compounds bind within the carbohydrate‐binding site. The atomic structures revealed that binding interactions mainly occur with the galactose moiety at the non‐reducing end, primarily with subsites C and D of the CRD, differing from oligo‐lactosamine which bind more consistently across the whole groove formed by the five subsites (A‐E) of the galectin‐3 CRD. [ABSTRACT FROM AUTHOR]

We review the current state of mathematical modeling of cartilage pattern formation in vertebrate limbs. We place emphasis on several reaction–diffusion type models that have been proposed in the last few years. These models are grounded in more detailed knowledge of the relevant regulatory processes than previous ones but generally refer to different molecular aspects of these processes. Considering these models in light of comparative phylogenomics permits framing of hypotheses on the evolutionary order of appearance of the respective mechanisms and their roles in the fin‐to‐limb transition. This article is categorized under:Analytical and Computational Methods > Computational MethodsModels of Systems Properties and Processes > Mechanistic ModelsDevelopmental Biology > Developmental Processes in Health and DiseaseAnalytical and Computational Methods > Analytical Methods [ABSTRACT FROM AUTHOR]

Heart failure (HF) is a serious disease syndrome characterized by elevated pro‐inflammatory cytokines and inflammatory mediators presume to have significant contribution on disease progression. Galectins are carbohydrate‐binding proteins responsible of various physiological functions. Role of galectins in heart failure has been ill‐defined. In the present case‐controls study, 136 patients clinically diagnosed with heart failure and 125 healthy Chinese controls were recruited. Levels of galectins (Gal‐1, 3 and 9) and cytokines (IFN‐γ, IL‐17A, IL‐4 and TGF‐β) were quantified by ELISA. Increased levels of galectin‐1 and 3 was observed in HF patients and associated with clinical severity. In addition, pro‐inflammatory cytokines such as IFN‐γ and IL‐17A were increased in patients whereas, anti‐inflammatory TGFβ was decreased. Galectin‐3 was positively correlated with IFN‐γ, IL‐17A and inversely with TGF‐β. Furthermore, ROC curve analysis suggested galectin‐3 as a promising biomarker for diagnosis and HF and clinical severity. Interestingly, a two‐year follow‐up indicated significant association of elevated galectin‐3 with mortality due to HF. In conclusion, galectin‐3 associated with HF and clinical manifestations possibly by inducing pro‐inflammatory cytokines and could be a possible biomarker of HF and severe clinical conditions. [ABSTRACT FROM AUTHOR]

In contrast to clathrin‐mediated endocytosis (CME) which is well characterized and understood, little is known about the regulation and machinery underlying clathrin‐independent endocytosis (CIE). There is also a wide variation in the requirements each individual CIE cargo has for its internalization. Recent studies have shown that CIE is affected by glycosylation and glycan interactions. We briefly review these studies and explore how these studies mesh with one another. We then discuss what this sensitivity to glycan interactions could indicate for the regulation of CIE. We address the spectrum of responses CIE has been shown to have with respect to changes in glycan interactions and attempt to reconcile disparate observations onto a shared conceptual landscape. We focus on the mechanisms by which cells can alter the glycan interactions at the plasma membrane and propose that glycosylation and glycan interactions could provide cells with a tool box with which cells can manipulate CIE. Altered glycosylation is often associated with a number of diseases and we discuss how under different disease settings, glycosylation‐based modulation of CIE could play a role in disease progression. Glycosylation and glycan interactions have been shown to affect clathrin‐independent endocytosis (CIE). We explore the implications of these findings and discuss how galectins and glycans can serve as extracellular machinery and may play a role in facilitating and modulating CIE. [ABSTRACT FROM AUTHOR]

In this study, we determined the genomic DNA sequences of the mucosal galectin‐encoding genes from all 19 species and subspecies of the genus Anguilla. The nucleotide sequences of the galectin genes were c. 2.3–2.5 kb long and the organisation of their four exons and three introns was conserved in all species. An unusual sequence was found in the fourth exon of Anguilla reinhardtii, resulting in a unique deduced amino‐acid sequence at the C‐terminus. All six amino‐acid residues important for β‐galactoside binding were conserved in three species, while one residue (R73) was substituted to K73 in the other 16 species–subspecies, including Anguilla marmorata. However, this substitution did not appear to affect the sugar‐binding ability of galectins because the galectin of A. marmorata was previously shown to bind to lactose. We also discuss the molecular evolution of galectins among Anguilla spp. and the homologues previously identified in Conger myriaster. [ABSTRACT FROM AUTHOR]

Galectin‐2 (Gal‐2) is a lectin thought to play protective roles in the gastrointestinal tract. Oxidation of mouse Gal‐2 (mGal‐2) by hydrogen peroxide (H2O2) results in the loss of sugar‐binding activity, whereas S‐nitrosylation of mGal‐2, which does not change its sugar‐binding profile, has been shown to protect the protein from H2O2‐induced inactivation. One of the two cysteine residues, C57, has been identified as being responsible for controlling H2O2‐induced inactivation; however, the underlying molecular mechanism has not been elucidated. We performed structural analyses of mGal‐2 using nuclear magnetic resonance (NMR) and found that residues near C57 experienced significant chemical shift changes following S‐nitrosylation, and that S‐nitrosylation slowed the H2O2‐induced aggregation of mGal‐2. We also revealed that S‐nitrosylation improves the thermal stability of mGal‐2 and that the solvent accessibility and/or local dynamics of residues near C57 and the local dynamics of the core‐forming residues in mGal‐2 are reduced by S‐nitrosylation. Structural models of Gal‐2 indicated that C57 is located in a hydrophobic pocket that can be plugged by S‐nitrosylation, which was supported by the NMR experiments. Based on these results, we propose two structural mechanisms by which S‐nitrosylation protects mGal‐2 from H2O2‐induced aggregation without changing its sugar‐binding profile: (a) stabilization of the hydrophobic pocket around C57 that prevents oxidation‐induced destabilization of the pocket, and (b) prevention of oxidation of C57 during the transiently unfolded state of the protein, in which the residue is exposed to H2O2. Database: Nuclear magnetic resonance assignments for non‐S‐nitrosylated mGal‐2 and S‐nitrosylated mGal‐2 have been deposited in the BioMagResBank ( http://www.bmrb.wisc.edu/) under ID code 27237 for non‐S‐nitrosylated mGal‐2 and ID code 27238 for S‐nitrosylated mGal‐2. [ABSTRACT FROM AUTHOR]

The galectin family comprises β-galactoside-binding proteins widely expressed in many organisms. There are at least 16 family members, which can be classified into three groups based on their carbohydrate-recognition domains. Pleiotropic functions of different galectins in physiological and pathological processes through extracellular or intracellular actions have been revealed. In the skin, galectins are expressed in a variety of cells, including keratinocytes, melanocytes, fibroblasts, dendritic cells, lymphocytes, macrophages and endothelial cells. Expression of specific galectins is reported to affect cell status, such as activation or death, and regulate the interaction between different cell types or between cells and the extracellular matrix. In vitro cellular studies, in vivo animal studies and studies of human clinical material have revealed the pathophysiologic roles of galectins in the skin. The pathogenesis of diverse non-malignant skin disorders, such as atopic dermatitis, psoriasis, contact dermatitis and wound healing, as well as skin cancers, such as melanoma, squamous cell carcinoma, basal cell carcinoma and cutaneous haematologic malignancy can be regulated by different galectins. Revelation of biological roles of galectins in skin may pave the way to future development of galectin-based therapeutic strategies for skin diseases. [ABSTRACT FROM AUTHOR]

A glyco-array platform has been developed, in which glycans are attached to plasmonic nanoparticles through strain-promoted azide-alkyne cycloaddition. Glycan-protein binding events can then be detected in a label-free manner employing surface-enhanced Raman spectroscopy (SERS). As proof of concept, we have analyzed the binding of Gal1, Gal3, and influenza hemagglutinins (HAs) to various glycans and demonstrated that binding partners can be identified with high confidence. The attraction of SERS for optical sensing is that it can provide unique spectral signatures for glycan-protein complexes, confirm identity through statistical validation, and minimizes false positive results common to indirect methods. Furthermore, SERS is very sensitive and has multiplexing capabilities thereby allowing the simultaneous detection of multiple analytes. [ABSTRACT FROM AUTHOR]

Background: Plasma galectin-3 (Gal-3) is elevated in, and drives, diverse systemic inflammatory disorders, including cancer, cardiovascular diseases, and diabetes. Circulating Gal-3 promotes tumorigenesis and metastasis, as well as fibrotic remodeling, and is a promising therapeutic target. Apheresis has proven utility in reducing circulating disease-promoting substances, exemplified by the success of lipoprotein apheresis (LA) in abrogating cardiovascular disease progression in drug-refractory hypercholesterolemia patients. We compared the clinical utility of two FDA-approved LA systems in reducing plasma Gal-3 in humans. Methods: Plasma Gal-3 levels were assessed by ELISA in blinded samples drawn pre- and post-apheresis from hypercholesterolemia patients ( n = 10/group) undergoing therapeutic LA using either a heparin-induced extracorporeal LDL precipitation (HELP) or dextran sulfate- adsorption (DSA) system. Results: Mean baseline plasma Gal-3 concentrations (±SD) were 14.3 ± 5.1 (range 6.6-22.8) and 14.5 ± 2.8 (range 10.6-19.8) ng/mL in the HELP and DSA groups, respectively. Post-apheresis Gal-3 levels were respectively reduced by 19.4% and 22.7% in the HELP ( P = 0.0094) and DSA ( P = 0.0027) systems (paired t-tests); the difference between devices was insignificant ( P = 0.5288; Mann-Whitney). Post-treatment Gal-3 levels were 11.3 ± 3.7 (HELP; range 4.5-16.3) and 11.3 ± 3.8 (DSA; range 7.5-20.7) ng/mL. Conclusions: Circulating Gal-3 levels showed a statistically significant decrease in humans undergoing therapeutic LA. Although absolute Gal-3 reduction was ≈19-23%, this effect, combined with reducing atherogenic LDL and other inflammation mediators (e.g., CRP, fibrinogen, Lp-PLA2), may enhance apheresis clinical benefits. Applying new Gal-3-specific extraction technologies to apheresis may be advantageous in treating diverse pathologies that are promoted by elevated plasma Gal-3. J. Clin. Apheresis 31:388-392, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Programs that control immune cell homeostasis are orchestrated through the coordinated action of a number of regulatory cell populations, including regulatory T cells, regulatory B cells, myeloid-derived suppressor cells, alternatively-activated macrophages and tolerogenic dendritic cells. These regulatory cell populations can prevent harmful inflammation following completion of protective responses and thwart the development of autoimmune pathology. However, they also have a detrimental role in cancer by favoring escape from immune surveillance. One of the hallmarks of regulatory cells is their remarkable plasticity as they can be positively or negatively modulated by a plethora of cytokines, growth factors and co-stimulatory signals that tailor their differentiation, stability and survival. Here we focus on the emerging roles of galectins, a family of highly conserved glycan-binding proteins in regulating the fate and function of regulatory immune cell populations, both of lymphoid and myeloid origins. Given the broad distribution of circulating and tissue-specific galectins, understanding the relevance of lectin–glycan interactions in shaping regulatory cell compartments will contribute to the design of novel therapeutic strategies aimed at modulating their function in a broad range of immunological disorders. [ABSTRACT FROM AUTHOR]

Galectins are an evolutionarily conserved family of proteins that translate glycan recognition into cellular effects. Galectin-11 is a unique member of the galectin family that is only expressed in ruminants such as sheep, goat and cattle and that plays a critical role in several important biological processes, such as reproduction and parasite-mediated innate immune responses. Currently, these two areas are of major importance for the sustainability of ruminant livestock production. Despite the emerging biological significance of galectin-11, no structural information is available. It is expected that structural studies will unravel the functional mechanisms of galectin-11 activity. Here, the expression, purification and crystallization of the ruminant-specific galectin-11 from domestic sheep and the collection of X-ray data to 2.0 Å resolution are reported. [ABSTRACT FROM AUTHOR]

CD6 is a lymphocyte glycoprotein receptor that physically associates with the antigen‐specific receptor complex at the center of the immunological synapse, where it interacts with its ligand CD166/ALCAM. The present work reports the carbohydrate‐dependent interaction of CD6 and CD166/ALCAM with Galectin‐1 and ‐3, two well‐known soluble mammalian lectins. Both galectins interfered with superantigen‐induced T cell proliferation and cell adhesion phenomena mediated by the CD6‐CD166/ALCAM pair, while CD6 expression protected cells from galectin‐induced apoptosis. The results suggest that interaction of Galectin‐1 and ‐3 with CD6 and CD166/ALCAM might modulate some relevant aspects of T cell physiology.Galectin‐1 and ‐3 are two new interacting proteins for CD6 and its ligand CD166/ALCAM. Galectin‐1 and ‐3 modulate T cell proliferation and adhesion involving CD6‐CD166/ALCAM. The intracellular region of CD6 has protective effects against galectin‐induced T cell apoptosis. The interaction of Galectin‐1 and ‐3 with CD6 has a modulatory effect on T cell physiology. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pro45 of ACG undergoes cis–trans isomerization upon ligand binding. [•] First report of the unique flexibility of the ligand-binding site of a galectin. [•] An induced-fit mechanism is responsible for the broad specificity of ACG. [Copyright &y& Elsevier]

We have developed an expeditious procedure to yield large amounts of orthogonally protected Gal- β1,3/4-GlcNAc, which allowed for the systematic introduction of a sulfate group onto the C3/C6 positions of Gal and/or the C6 position of GlcNAc. In particular, the disaccharide precursors were prepared in five or six steps and high overall yield from para-tolyl-6- O- tert-butyldiphenylsilyl-1-thio- β- D-galactopyranoside. After and steps, the final products were characterized by using several NMR methods to unambiguously confirm the location of each introduced sulfate group and they were examined for their binding specificity of human galectin-1 and galectin-8. [ABSTRACT FROM AUTHOR]

Axon membrane glycoproteins are essential for neuronal differentiation, although the mechanisms underlying their polarized sorting and organization are poorly understood. We describe here that galectin-4 (Gal-4), a lectin highly expressed in gastrointestinal tissues and involved in epithelial glycoprotein transport, is expressed by hippocampal and cortical neurons where it is sorted to discrete segments of the axonal membrane in a microtubule- and sulfatide-dependent manner. Gal-4 knockdown retards axon growth, an effect that can be rescued by recombinant Gal-4 addition. This Gal-4 reduction, as inhibition of sulfatide synthesis does, lowers the presence and clustered organization of axon growth-promoting molecule NCAM L1 at the axon membrane. Furthermore, we find that Gal-4 interacts with L1 by specifically binding to Lac NAc branch ends of L1 N-glycans. Impairing the maturation of these N-glycans precludes Gal-4/L1 association resulting in a failure of L1 membrane cluster organization. In all, Gal-4 sorts to axon plasma membrane segments by binding to sulfatide-containing microtubule-associated carriers and being bivalent, it organizes the transport of L1, and likely other axonal glycoproteins, by attaching them to the carriers through their Lac NAc termini. This mechanism would underlie L1 functional organization on the plasma membrane, required for proper axon growth. [ABSTRACT FROM AUTHOR]

We have investigated the expression and role of galectin-1 and other galectins in psoriasis and in the Th1/Th17 effector and dendritic cell responses associated with this chronic inflammatory skin condition. To determine differences between psoriasis patients and healthy donors, expression of galectins was analysed by RT-PCR in skin samples and on epidermal and peripheral blood dendritic cells by immunofluorescence and flow cytometry. In the skin of healthy donors, galectin-1, -3 and -9 were expressed in a high proportion of Langerhans cells. Also, galectins were differentially expressed in peripheral blood dendritic cell subsets; galectin-1 and galectin-9 were highly expressed in peripheral myeloid dendritic cells compared with plasmacytoid dendritic cells. We found that non-lesional as well as lesional skin samples from psoriasis patients had low levels of galectin-1 at the mRNA and protein levels, in parallel with low levels of IL-10 mRNA compared with skin from healthy patients. However, only lesional skin samples expressed high levels of Th1/Th17 cytokines. The analysis of galectin-1 expression showed that this protein was down-regulated in Langerhans cells and dermal dendritic cells as well as in peripheral blood CD11c+ DCs from psoriasis patients. Expression of galectin-1 correlated with IL-17 and IL-10 expression and with the psoriasis area and index activity. Addition of galectin-1 to co-cultures of human monocyte-derived dendritic cells with autologous T lymphocytes from psoriasis patients attenuated the Th1 response. Conversely, blockade of galectin binding increased IFNγ production and inhibited IL-10 secretion in co-cultures of monocyte-derived dendritic cells with CD4+ T cells. Our results suggest a model in which galectin-1 down-regulation contributes to the exacerbation of the Th1/Th17 effector response in psoriasis patients. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bivalves are employed widely as biomonitors of metal pollution and proteomics has increasingly been applied to solve ecotoxicological issues. This study aimed to investigate the effects of Cd exposure on the bioaccumulation of other trace elements and reveal the molecular mechanisms using proteomics technologies. The results showed that Cd exposure resulted in remarkable changes in body concentrations of Zn, Cu, Ag, Co, Ni, Pb, and Se in four marine bivalves (scallop Chlamys nobilis, clam Ruditapes philippinarum, mussel Perna viridis, and oyster Saccostrea cucullata). Generally, the bivalves exposed to higher Cd concentration accumulated higher concentrations of Zn, Cu, and Se, but a lower concentration of Co. The accumulation of Ag, Ni, and Pb was specific for different species. The data strongly suggest that the influences of one metal exposure on the bioaccumulation of other metals/metalloids need to be considered in interpreting body concentrations of the elements in the biomonitors. Cd exposure had little effect on bivalve proteomes, and the identified proteins were insufficient to explain the observed disruption of trace element metabolism. However, protein expression signatures composed of the altered proteins could distinguish the clams and the mussels with different body Cd levels. The strong up-regulation of galectin in Cd-exposed oysters indicated the protein as a novel biomarker in environmental monitoring. Environ. Toxicol. Chem. 2012;31:1292-1300. © 2012 SETAC [ABSTRACT FROM AUTHOR]

Although lectins are “hard-wired” in the germline, the presence of tandemly arrayed carbohydrate recognition domains (CRDs), of chimeric structures displaying distinct CRDs, of polymorphic genes resulting in multiple isoforms, and in some cases, of a considerable recognition plasticity of their carbohydrate binding sites, significantly expand the lectin ligand-recognition spectrum and lectin functional diversification. Analysis of structural/functional aspects of galectins and F-lectins—the most recently identified lectin family characterized by a unique CRD sequence motif (a distinctive structural fold) and nominal specificity for l-Fuc-has led to a greater understanding of self/nonself recognition by proteins with tandemly arrayed CRDs. For lectins with a single CRD, however, recognition of self and nonself glycans can only be rationalized in terms of protein oligomerization and ligand clustering and presentation. Spatial and temporal changes in lectin expression, secretion, and local concentrations in extracellular microenvironments, as well as structural diversity and spatial display of their carbohydrate ligands on the host or microbial cell surface, are suggestive of a dynamic interplay of their recognition and effector functions in development and immunity. [ABSTRACT FROM AUTHOR]

During sexual transmission, HIV-1 must overcome physiological barriers to establish a founder cell population. Viral adhesion represents a bottleneck for HIV-1 propagation that the virus widens by exploiting some specific host factors. Recognition of oligomannosyl glycans of gp120 by C-type lectins is one such example. Recent works suggest that complex glycans of gp120 are recognized by another host lectin, galectin-1. This interaction results in rapid association of HIV-1 to susceptible cells and facilitates infection. The peculiar presentation of complex glycans on gp120 seems to impart specificity for galectin-1, as another member of the same family, galectin-3, is unable to bind gp120 or enhance HIV-1 infection. Other studies have shown that galectin-9 could also increase HIV-1 infectivity but via an indirect mechanism. Thus, current research suggests that galectins play various roles in HIV-1 pathogenesis. Drug discovery approaches targeting host lectins at early steps could benefit the current arsenal of antiretrovirals. [ABSTRACT FROM AUTHOR]

The trafficking of leukocytes from the blood stream to the surrounding tissue is a fundamental feature of an inflammatory response. Although many of the adhesion molecules and chemokines that direct leukocyte trafficking have been identified, there is still much to be discovered, particularly with regard to the persistence of leukocyte infiltrates in chronic inflammation. Elucidating the molecular mechanisms involved in this process is critical to understanding and treating inflammatory pathologies. Recent studies have identified members of the galectin family as immunoregulatory proteins. Included among the actions of galectins are modulatory effects, both positive and negative, on leukocyte recruitment. The focus of this review is to summarize current knowledge on the role of galectins in leukocyte trafficking during inflammation. A better understanding of the function of this family of endogenous lectins will open new avenues for innovative drug discovery. [ABSTRACT FROM AUTHOR]

M. Stancic, J. van Horssen, V. L. Thijssen, H.-J. Gabius, P. van der Valk, D. Hoekstra and W. Baron (2011) Neuropathology and Applied Neurobiology 37, 654-671 Increased expression of distinct galectins in multiple sclerosis lesions Aims: Multiple sclerosis (MS) is a chronic progressive degenerative disorder of the central nervous system, characterized by inflammation, demyelination, ultimate failure of remyelination and axonal loss. Current research identifies galectins, adhesion/growth-regulatory effectors binding β-galactosides, peptide motifs and lipids, as important immunomodulators in diverse inflammatory diseases. However, little is known about their expression, cellular localization and role in human central nervous system tissue. To identify a potential role of galectins in MS, their expression and localization in control white matter (CWM) and demyelinated MS lesions were examined. Methods: qPCR, Western blot and immunohistochemical analyses were performed on human post mortem CWM and MS lesions at different stages. Cultured astrocytes, derived from healthy subjects and MS patients, were analysed similarly. Results: Among 11 different galectins tested, galectins-1, -3, -8 and -9 were present at detectable levels in CWM, and, interestingly, significantly enhanced in active MS lesions. On the cellular level, galectins localized to microglia/macrophages, astrocytes and endothelial cells. Intriguingly, galectin-9 displayed a distinctly different intracellular localization in microglia/macrophages when comparing active and inactive MS lesions, being restricted to the nuclei in active lesions, and primarily localizing in the cytoplasm in inactive lesions. Furthermore, enhanced levels of galectin-1, detected as dimers in Western blot analysis, were released by cultured astrocytes from MS patients. Conclusions: This study provides a detailed analysis of galectins in MS lesions and assigns distinct galectins to different aspects of the disease. Thus, besides being known as modulators of inflammatory processes, our findings suggest additional association of distinct galectins with MS pathology. [ABSTRACT FROM AUTHOR]

Platelet activation at sites of vascular injury leads to the formation of a hemostatic plug. Activation of platelets is therefore crucial for normal hemostasis. However, uncontrolled platelet activation may also lead to the formation of occlusive thrombi that can cause ischemic events. Platelets can be activated by soluble molecules including thrombin, TXA [ABSTRACT FROM AUTHOR]

Remmelink M, de Leval L, Decaestecker C, Duray A, Crompot E, Sirtaine N, André S, Kaltner H, Leroy X, Gabius H-J & Saussez S (2011) Histopathology 543-556 This study tests the hypothesis that histopathological fingerprinting of galectins, which are emerging multifunctional effectors in cell sociology, could refine the differential diagnosis of salivary tumours. We applied non-crossreactive polyclonal antibodies against galectin-1 (Gal-1), galectin-3 (Gal-3), galectin-7 (Gal-7) and galectin-8 (Gal-8) for immunohistochemical analysis of salivary gland tumours (72 cases with benign disease and 39 cases with malignancy) and 29 control specimens. The principal positivity of cases, the site of signal presence and the quantitative parameters concerning percentage of positive cells and labelling intensity were determined. Acinic cell and adenoid cystic carcinomas (specifically tubular and cribriform types) shared the expression signature of Gal-1, Gal-3 and Gal-8 presence combined with Gal-7 absence. Mucoepidermoid carcinomas presented a unique profile based on cytoplasmic Gal-1, Gal-3, Gal-7 and Gal-8 localization in the intermediate cells. Adenomas were separable from malignancy by a consistent decrease in the labelling index (LI) for Gal-7 and Gal-8 (LI Gal-7, P < 10; LI Gal-8, P = 0.001). When present, staining for the tumour suppressor p16 coincided with Gal-1 presence. Expression profiling of the four tested galectins in salivary gland tumours revealed non-uniform staining patterns with discriminatory potential based on intracellular localization and quantitative aspects. [ABSTRACT FROM AUTHOR]

Zebrafish ( Danio rerio) are an important developmental and embryological model given the optical clarity of the embryos and larvae, which permits real-time viewing of developing pathologies. More recently, a broader scope for these vertebrates to model a range of human diseases, including some cancers, has been indicated. Zebrafish Drgal1-L2 has been identified as an orthologue of mammalian galectin-1, which is is a carbohydrate-binding protein that exhibits β-galactoside-binding specificity and which is overexpressed by many aggressive human cancers. This study describes the cloning, expression in Escherichia coli, purification and crystallization of recombinant Drgal1-L2 protein in the presence of lactose (ligand). X-ray diffraction data from these novel crystals of zebrafish Drgal1-L2 were collected to a resolution of 1.5 Å using a synchrotron-radiation source, enabling their characterization. [ABSTRACT FROM AUTHOR]

The tumor suppressor p16INK4a has functions beyond cell-cycle control via cyclin-dependent kinases. A coordinated remodeling of N- and O-glycosylation, and an increase in the presentation of the endogenous lectin galectin-1 sensing these changes on the surface of p16INK4a-expressing pancreatic carcinoma cells (Capan-1), lead to potent pro-anoikis signals. We show that the p16INK4a-dependent impact on growth-regulatory lectins is not limited to galectin-1, but also concerns galectin-3. By monitoring its expression in relation to p16INK4a status, as well as running anoikis assays with galectin-3 and cell transfectants with up- or downregulated lectin expression, a negative correlation between anoikis and the presence of this lectin was established. Nuclear run-off and northern blotting experiments revealed an effect of the presence of p16INK4a on steady-state levels of galectin-3-specific mRNA that differed from decreasing the transcriptional rate. On the cell surface, galectin-3 interferes with galectin-1, which initiates signaling toward its pro-anoikis activity via caspase-8 activation. The detected opposite effects of p16INK4a at the levels of growth-regulatory galectins-1 and -3 shift the status markedly towards the galectin-1-dependent pro-anoikis activity. A previously undescribed orchestrated fine-tuning of this effector system by a tumor suppressor is discovered. [ABSTRACT FROM AUTHOR]

The molecular mechanics/generalized Born surface area (MM/GBSA) method has been investigated with the aim of achieving a statistical precision of 1 kJ/mol for the results. We studied the binding of seven biotin analogues to avidin, taking advantage of the fact that the protein is a tetramer with four independent binding sites, which should give the same estimated binding affinities. We show that it is not enough to use a single long simulation (10 ns), because the standard error of such a calculation underestimates the difference between the four binding sites. Instead, it is better to run several independent simulations and average the results. With such an approach, we obtain the same results for the four binding sites, and any desired precision can be obtained by running a proper number of simulations. We discuss how the simulations should be performed to optimize the use of computer time. The correlation time between the MM/GBSA energies is ∼5 ps and an equilibration time of 100 ps is needed. For MM/GBSA, we recommend a sampling time of 20–200 ps for each separate simulation, depending on the protein. With 200 ps production time, 5–50 separate simulations are required to reach a statistical precision of 1 kJ/mol (800–8000 energy calculations or 1.5–15 ns total simulation time per ligand) for the seven avidin ligands. This is an order of magnitude more than what is normally used, but such a number of simulations is needed to obtain statistically valid results for the MM/GBSA method. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 [ABSTRACT FROM AUTHOR]

Malignant gliomas, especially glioblastomas, are associated with a dismal prognosis. Despite advances in diagnosis and treatment, glioblastoma patients still have a median survival expectancy of only 14 months. This poor prognosis can be at least partly explained by the fact that glioma cells diffusely infiltrate the brain parenchyma and exhibit decreased levels of apoptosis, and thus resistance to cytotoxic drugs. Galectins are a family of mammalian beta-galactoside-binding proteins characterized by a shared characteristic amino acid sequence. They are expressed differentially in normal vs. neoplastic tissues and are known to play important roles in several biological processes such as cell proliferation, death and migration. This review focuses on the role played by galectins, especially galectin-1 and galectin-3, in glioma biology. The involvement of these galectins in different steps of glioma malignant progression such as migration, angiogenesis or chemoresistance makes them potentially good targets for the development of new drugs to combat these malignant tumors. [ABSTRACT FROM AUTHOR]

Galectins, β-galactoside-binding animal lectins, are differentially expressed by various immune cells as well as a wide range of other cell types. Extracellularly, galectins are able to exhibit bivalent or multivalent interactions with cell-surface glycans on various immune cells and exert various effects. These include cytokine and mediator production, cell adhesion, apoptosis, and chemoattraction. In addition, they can form lattices with cell-surface glycoprotein receptors, resulting in modulation of receptor functions, including clustering and endocytosis. Intracellularly, galectins can participate in signaling pathways and modulate biologic responses. These include apoptosis, cell differentiation, and cell migration. Thus, a large body of literature indicates that galectins play important roles in the immune and inflammatory responses through regulating the homeostasis and functions of immune cells. The use of mice deficient in individual galectins has provided additional evidence for the contributions of these proteins to these responses. Current research indicates that galectins play important roles in the development of acute inflammation as well as chronic inflammation associated with allergies, autoimmune diseases, atherosclerosis, infectious processes, and cancer. Thus, recombinant proteins or specific galectin inhibitors may be used as therapeutic agents for inflammatory diseases. [ABSTRACT FROM AUTHOR]

The galectins, a family of lectins, modulate distinct cellular processes, such as cancer progression, immune response and cellular development, through their specific binding to extracellular or intracellular ligands. In the past few years, research has unravelled interactions of different galectins with lipids and glycoproteins in the outer milieu or in the secretory pathway of cells. Interestingly, these lectins do not possess a signalling sequence to enter the endoplasmic reticulum as a starting point for the classical secretory pathway. Instead they use a so-called non-classical mechanism for translocation across the plasma membrane and/or into the lumen of transport vesicles. Here, they stabilize transport platforms for apical trafficking or sort apical glycoproteins into specific vesicle populations. Modes of ligand interaction as well as the modulation of binding activities and trafficking pathways are discussed in this review. [ABSTRACT FROM AUTHOR]

Galectin1, the prototype member of a family of carbohydrate binding proteins, is involved in muscle stem cell behavior and in tissue regeneration after muscle injury in adult mice. Here, we addressed the question of when this gene is first acting in the muscle lineage. We found that Galectin1 is an early marker of myogenesis as the transcripts and protein are initially confined to the somites, starting from day 9.0 of embryogenesis. We next investigated its relationship with the muscle determination factors, Myf5 and Myod. By comparing the spatio-temporal distribution of Galectin1 transcripts in control and Myf5 null mutant embryos, we were able to establish that it acts downstream of Myf5. However, early myogenesis does not seem affected in Galectin1 null mutant embryos indicating that, unlike in the adult, Galectin1 does not play a role in muscle fate acquisition during development. [ABSTRACT FROM AUTHOR]

The article presents a research study which examines the insecticidal actions of mammalian galectin-1 against diamondback moth. According to the article, the development of diamondback moth or Plutella xylostella larvae was disturbed after they were fed with recombinant GAL 1. It highlights that the carbohydrate recognition of GAL 1 recognizes the structural motif N-acetyl lactosamine

Basal, activation, and arrest signaling in T cells determines survival, coordinates responses to pathogens, and, when dysregulated, leads to loss of self-tolerance and autoimmunity. At the T-cell surface, transmembrane glycoproteins interact with galectins via their N-glycans, forming a molecular lattice that regulates membrane localization, clustering, and endocytosis of surface receptors. Galectin–T-cell receptor (TCR) binding prevents ligand-independent TCR signaling via Lck by blocking spontaneous clustering and CD4-Lck recruitment to TCR, and in turn F-actin transfer of TCR/CD4-Lck complexes to membrane microdomains. Peptide–major histocompatibility complexes overcome galectin–TCR binding to promote TCR clustering and signaling by Lck at the immune synapse. Galectin also localizes the tyrosine phosphatase CD45 to microdomains and the immune synapse, suppressing basal and activation signaling by Lck. Following activation, membrane turnover increases and galectin binding to cytotoxic T-lymphocyte antigen-4 (CTLA-4) enhances surface expression by inhibiting endocytosis, thereby promoting growth arrest. Galectins bind surface glycoproteins in proportion to the branching and number of N-glycans per protein, the latter an encoded feature of protein sequence. N-glycan branching is conditional to the activity of Golgi N-acetylglucosaminyl transferases I, II, IV and V (Mgat1, 2, 4, and 5) and metabolic supply of their donor substrate UDP-GlcNAc. Genetic and metabolic control of N-glycan branching co-regulate homeostatic set-points for basal, activation, and arrest signaling in T cells and, when disturbed, result in T-cell hyperactivity and autoimmunity. [ABSTRACT FROM AUTHOR]

Dirofilaria immitis is the agent of the heartworm disease in canids and felids, and of pulmonary dirofilariosis in man. Like other filariae, D. immitis harbours endosymbion Wolbachia bacteriae. In this work we analyse the response of specific IgE antibodies against both D. immitis antigens and the Wolbachia surface protein (WSP) in two groups of persons living in an area of canine endemia, one presenting high levels of total IgE (group 1) and other with normal levels (group 2). Infections with D. immitis were demonstrated by the presence of specific IgG in 228 individuals(48·8%) of the group 1 and only in one of the group 2. Specific IgE antibody response against D. immitis antigens was detected only in individuals of the group 1. IgE response against WSP was not detected in any group. The IgE response was directed mainly against two molecules of 33 and 42 kDa of the antigenic extract of D. immitis . These molecules were identified by mass spectrometry as a galectin and an aldolase, respectively. Their possible role in the survival mechanisms of the parasite and their contribution to development of allergic reactions in individuals resident in areas with heartworm disease are discussed. [ABSTRACT FROM AUTHOR]

CD45, an abundant and highly glycosylated cell-surface protein, is a critical regulator of T-cell development. CD45 is differentially glycosylated throughout the life of a T cell, and the glycosylation state of CD45 controls recognition by various binding partners, affects intracellular signaling by the cytoplasmic tyrosine phosphatase domain and modulates the response of the T cell to antigen. Although the importance of CD45 during T-cell development has been established, it is becoming increasingly clear that glycosylation of CD45 is a dynamic process that modifies T-cell survival, activation and immune function. In this review, we address changes that occur in CD45 glycosylation during T-cell development and differentiation, describe carbohydrate-binding proteins that recognize differentially glycosylated forms of CD45, and discuss how differential glycosylation alters the T-cell response to a variety of signals involved in selection, activation and apoptosis.Immunology and Cell Biology (2008) 86, 608–615; doi:10.1038/icb.2008.46; published online 8 July 2008 [ABSTRACT FROM AUTHOR]

Abstract: We isolated mouse embryo fibroblasts (MEFs) from N-acetylglucosaminyltransferase Va (GnT-Va) knockout mice and studied the effects of loss of expression of GnT-Va on asparagine-linked glycans (N-glycan) synthesis and the gene expression of groups of glycosyltransferases and galectins. Loss of GnT-Va expression caused aberrant expression of several N-glycan structures, including N-linked β(1,6) branching, poly-N-lactosamine, bisecting N-acetylglucosamine (GlcNAc) and sialic acid. Using quantitative reverse transcriptase-PCR (qRT-PCR), altered gene expression of several groups of glycosyltransferases and galectins was observed in GnT-Va null MEFs, supporting the observed changes in N-glycan structures. These results suggest that genetic disruption of GnT-Va ultimately resulted in altered MEFs gene expression and decreased tumor progression associated with loss of GnT-Va observed may result in part from a combination of effects from these altered gene expressions. [Copyright &y& Elsevier]

Recently, considerable attention has been focused on the identification of clinically relevant prognostic markers for primary central nervous system lymphomas (PCNSL). The present study investigated whether three morphological features, i.e. necrosis, reactive perivascular T-cell infiltrate and endothelial hyperplasia, and galectin-1 and galectin-3 immunohistochemical expression have prognostic roles in a series of 58 PCNSL samples from 44 immunocompetent and 14 immunocompromised patients. The presence of endothelial hyperplasia (identified in 21% of the assessable cases) was identified as a bad prognostic factor for immunocompetent PCNSL patients, whereas the other morphological features were not associated with any prognostic value. Lymphomatous cells of eight PCNSL cases expressed galectin-3 without any prognostic value, and lymphomatous cells did not express galectin-1. In contrast, endothelial expression of galectin-3 was identified (by means of uni- and multi-variate analyses) as a bad prognostic factor for immunocompetent PCNSL patients. In addition, a combination of endothelial hyperplasia and/or endothelial galectin-3 expression was shown to be an independent prognostic factor for immunocompetent PCNSL patients treated with methotrexate-based chemotherapy. In summary, this study suggests that endothelial-related markers can identify risk groups of PCNSL patients and indicates that galectin-3 could be involved in PCNSL angiogenesis. [ABSTRACT FROM AUTHOR]

Head and neck squamous cell carcinomas (HNSCCs) remain a significant cause of morbidity worldwide. Biological therapies able to induce and/or upregulate antitumor immune responses could represent a complementary approach to conventional treatments for patients with HNSCC because, despite advances in surgery, radiotherapy, and chemotherapy, the overall survival rates for these patients have not changed over recent decades. Galectins are involved in the control of cell proliferation, cell death, and cell migration and in the modulation of various functions of the immune system. In this context, galectin-1 is known to protect HNSCCs from the immune system. The present review details the involvement of galectins in HNSCC biology and suggests a number of approaches to reduce the levels of expression of galectin-1 in HNSCCs, with the aim of improving the efficiency of HNSCC immunotherapy. © 2007 Wiley Periodicals, Inc. Head Neck, 2007 [ABSTRACT FROM AUTHOR]

Expression of the tumor suppressor p16INK4a after stable transfection can restore the susceptibility of epithelial tumor cells to anoikis. This property is linked to increases in the expression and cell-surface presence of the fibronectin receptor. Considering its glycan chains as pivotal signals, we assumed an effect of p16INK4a on glycosylation. To test this hypothesis for human Capan-1 pancreatic carcinoma cells, we combined microarray for selected glycosyltransferase genes with 2D chromatographic glycan profiling and plant lectin binding. Major differences between p16-positive and control cells were detected. They concerned expression of β1,4-galactosyltransferases (down-regulation of β1,4-galactosyltransferases-I/V and up-regulation of β1,4-galactosyltransferase-IV) as well as decreased α2,3-sialylation of O-glycans and α2,6-sialylation of N-glycans. The changes are compatible with increased β1-integrin maturation, subunit assembly and binding activity of the α5β1-integrin. Of further functional relevance in line with our hypothesis, we revealed differential reactivity towards endogenous lectins, especially galectin-1. As a result of reduced sialylation, the cells' capacity to bind galectin-1 was enhanced. In parallel, the level of transcription of the galectin-1 gene increased conspicuously in p16INK4a-positive cells, and even figured prominently in a microarray on 1996 tumor-associated genes and in proteomic analysis. The cells therefore gain optimal responsiveness. The correlation between genetically modulated galectin-1 levels and anoikis rates in engineered transfectants inferred functional significance. To connect these findings to the fibronectin receptor, galectin-1 was shown to be co-immunoprecipitated. We conclude that p16INK4a orchestrates distinct aspects of glycosylation that are relevant for integrin maturation and reactivity to an endogenous effector as well as the effector's expression. This mechanism establishes a new aspect of p16INK4a functionality. [ABSTRACT FROM AUTHOR]

The efficacy of vaccination against Haemonchus contortus infection with two recombinant proteins, rHco-gal-m and rHco-gal-f, was studied in 9–10-month-old goats. Vaccination with 100 µg protein reduced faecal egg output and worm burdens by 37·25% and 41·1%, respectively. Corresponding reductions with 200 µg protein were 48·03% and 46·19%. Vaccinated groups had significantly higher IgG levels than the negative and positive controls. Significant negative correlations were detected between IgG level, mucosal homogenate IgA concentration, haemoglobin and abomasal worm burden at necropsy. By contrast a positive correlation was found between the percentage of B cells, monocytes and abomasal worm burden. These findings suggested that vaccination with a combination of recombinant rHco-gal-m/f proteins had a role in protecting goats against H. contortus infection. [ABSTRACT FROM AUTHOR]

Our previous studies have found that expression of p27 in oligodendrocytes enhances myelin basic protein (MBP) gene expression through a mechanism that involves the transcription factor Sp1. In this study we show that this activation only requires the N-terminal 45 amino acids of p27 containing a functional cyclin-binding motif. In an effort to identify other cofactors that are involved in the p27-mediated activation of MBP gene expression, a yeast two-hybrid assay was performed using an N-terminal truncated p27 and a mouse embryo cDNA library. Galectin-4 was found to interact with p27 in the yeast two-hybrid assay. This novel interaction was also confirmed using a glutathione-S-transferase interaction assay and immunoprecipitation assays. Expression of galectin-4 in primary oligodendrocytes was confirmed by western blot. Additionally, the MBP promoter could be activated by expression of galectin-4 in CG4 oligodendrocytes, similar to the effects of increased p27 levels. We also show that Sp1 and galectin-4 interact in cells, while a complex of all three proteins could not be found. We conclude that galectin-4 is involved in the p27-mediated activation of the MBP gene, possibly through modulation of the glycosylation status of the transcription factor Sp1. [ABSTRACT FROM AUTHOR]