Sialylated Complex-type N-Glycans Enhance the Signaling Activity of Soluble Intercellular Adhesion Molecule-1 in Mouse Astrocytes (original) (raw)
Related papers
Open Glycoscience, 2008
Soluble intercellular adhesion molecule-1 (sICAM-1) is elevated in the cerebrospinal fluid of patients with severe brain trauma and mouse sICAM-1 induces the production of macrophage inflammatory protein-2 (MIP-2) in mouse astrocytes. The production of MIP-2 is greatly enhanced when sICAM-1 contains sialylated complex-type N-glycans (sICAM-1-CT) as produced by Chinese hamster ovary (CHO) cells. By contrast, sICAM-1 from the Lec1 mutant of CHO cells (sICAM-1-HM), containing only high mannose-type N-glycans, is relatively inactive. Here we show that the Nglycans of sICAM-1-CT are mostly 2,3-sialylated bi-, tri-, and tetraantennary complex-type structures with varying amounts of core fucosylation. Unexpectedly, sICAM-1-CT and sICAM-1-HM bound equivalently to mouse astrocytes. Enhanced MIP-2 induction by sICAM-1-CT was associated with a more rapid, higher level, and prolonged MIP-2 response as well as sICAM-1-CT accumulation at the plasma membranes of mouse astrocytes. These results show that glycosylation of sICAM-1 contributes to its signaling properties at the astrocyte cell surface, and suggest that altered glycosylation which might arise as a result of inflammation could regulate the bioactivity of sICAM-1.
Glycobiology, 2006
Intercellular adhesion molecule-1 (ICAM-1) is a heavily N-glycosylated transmembrane protein comprising five extracellular Ig-like domains. The soluble isoform of ICAM-1 (sICAM-1), consisting of its extracellular part, is elevated in the cerebrospinal fluid of patients with severe brain trauma. In mouse astrocytes, recombinant mouse sICAM-1 induces the production of the CXC chemokine macrophage inflammatory protein-2 (MIP-2). MIP-2 induction is glycosylation dependent, as it is strongly enhanced when sICAM-1 carries sialylated, complex-type N-glycans as synthesized by wild-type Chinese hamster ovary (CHO) cells. The present study was aimed at elucidating the N-glycosylation of mouse sICAM-1 expressed in wild-type CHO cells with regard to sialylation, N-glycan profile, and N-glycosylation sites. Ion-exchange chromatography and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) of the released N-glycans showed that sICAM-1 mostly carried di- ...
Lipopolysaccharide changes sialylation pattern in the mouse central nervous system
2012
Sialylated glycoconjugates seem to play crucial role in the mechanisms that control the most important functions of the body. Sialylation is an important mechanism for the regulation of intercellular interactions that underlie neuronal plasticity as well as immune defense in the central nervous system (CNS). In this study, we analyzed the effect of lipopolysaccharide (LPS) on sialylation pattern in several regions of CNS. Additionally, we tested the effects of inflammatory stimulation on Siglec-F expression in microglial cells. Using lectin blotting with Maackia amurensis and Sambucus nigra agglutinins and immunostaining with antibody directed against PSA-NCAM we demonstrated altered expression of sialylated glycoconjugates differentially due to LPS-induced inflammation. We found that LPS caused significant increase of α2,3and α2,6-linked sialic acids in the hippocampus and spinal cord. In the prefrontal cortex, the level of α2,3-linked sialic acids in selected glycoconjugates tended to be increased (p>0.05), while α2,6-linked sialic acids were reduced (p<0.05), while the expression of PSA-NCAM in all analyzed structures were significantly higher in comparison to the control group. The expression of Siglec-F in microglial cells stimulated with LPS remained unchanged. Given the significance of glycans in the brain biology we can conclude that sialic acids and their receptors Siglec may be crucial regulators of immune response in the CNS.
Journal of Neurochemistry, 2002
Severe traumatic brain injury stimulates the release of soluble intercellular adhesion molecule-1 (sICAM-1) into CSF. Studies in cultured mouse astrocytes suggest that sICAM-1 induces the production of macrophage inflammatory protein-2 (MIP-2). In the present study, we investigated the underlying mechanisms for MIP-2 induction. sICAM-1 induced MIP-2 in astrocytes lacking membrane-bound ICAM-1, indicating that its action is due to heterophilic binding to an undescribed receptor rather than homophilic binding to surface ICAM-1. Signal transduction may be mediated by src tyrosine kinases, as the src tyrosine kinase inhibitors herbimycin A and PP2 abolished MIP-2 induction by sICAM-1. Phosphorylation of p42/44 mitogen-activated protein kinase (MAPK), but not of p38 MAPK, occurred further downstream, as evidenced by western blot analysis combined with the use of herbimycin A and specific MAPK inhibitors. By contrast, induction of MIP-2 by tumour necrosis factor-a (TNF-a) involved both p42/44 MAPK and p38 MAPK. Following stimulation with either sICAM-1 or TNF-a, astrocyte supernatants promoted chemotaxis of human neutrophils and incubation of these supernatants with anti-MIP-2 antibodies more efficiently suppressed the migration induced by sICAM-1 than by TNF-a. These results show that sICAM-1 induces the production of biologically active MIP-2 in astrocytes by heterophilic binding to an undefined receptor and activation of src tyrosine kinases and p42/44 MAPK. Keywords: astrocytes, macrophage inflammatory protein-2, p42/44 mitogen-activated protein kinase, soluble intercellular adhesion molecule-1, src tyrosine kinases. adhesion molecule-1; ICAM-1-/-, ICAM-1 knockout; IL, interleukin; LFA-1, leucocyte function associated antigen-1; Mac-1, macrophage antigen-1; MAPK, mitogen-activated protein kinase; MIP, macrophage inflammatory protein; PMN, polymorphonuclear granulocytes; RANTES, regulated upon activation, normal T-cell expressed and secreted; sICAM-1, soluble intercellular adhesion molecule-1; TNF-a, tumour necrosis factor-a; WT, wild-type.
European Journal of Biochemistry, 2001
Polysialylation of the neural cell adhesion molecule (N-CAM) is known to destabilize cell-cell adhesion and to promote plasticity in cell-cell interactions. To gain more insights into the molecular mechanisms regulating the selective expression of polysialic acid on distinct glycan chains, the underlying core structures of polysialylated N-CAM glycans from newborn mouse brain were examined. Starting from low picomolar amounts of oligosaccharides, a multistep approach was used that was based on various mass spectrometric techniques with minimized sample consumption. Evidence could be provided that polysialylated murine N-CAM glycans comprise diantennary, triantennary and tetraantennary core structures carrying, in part, type-1 N-acetyllactosamine antennae, sulfate groups linked to terminal galactose or subterminal N-acetylglucosamine residues and, as a characteristic feature, a sulfated glucuronic acid unit which was bound exclusively to C3 of terminal galactose in Mana3-linked type-2 antennae. Hence, our results reveal that part of the murine N-CAM carbohydrates are modified within a single oligosaccharide by polysialic acid plus a HSO 3-GlcA-moiety, which is likely to represent a HNK1-epitope. As HNK1-carbohydrates are also known to modulate cell-cell interactions, the simultaneous presence of both carbohydrate epitopes may reflect a new mechanism involved in the fine-tuning of N-CAM functions.
European Journal of Biochemistry, 1998
Myelin-associated glycoprotein (MAG) and sialoadhesin (Sn) bind to sialylated glycans on cell surfaces and are thought to be involved in cell-cell interactions. In order to investigate how the interactions of these proteins are influenced by the glycan structure, we compared the inhibitory potencies of different synthetic monovalent oligosaccharides and polyvalent polyacrylamide derivatives. Using oligosaccharides with modifications in the sialic acid, galactose or N-acetylglucosamine moieties, we could demonstrate that both MAG and Sn bind with high preference to alpha2,3-linked sialic acid and interact at least with the three terminal monosaccharide units. For MAG, contacts with even more distant monosaccharides are likely, since pentasaccharides are bound better than trisaccharides. Also, an additional sialic acid at position six of the third-terminal monosaccharide unit enhances binding to MAG, whereas it does not influence binding to Sn significantly. Modifications of the sialic acid glycerol side chain demonstrated that the hydroxy groups at positions 8 and 9 are required for binding to both proteins. Surprisingly, MAG binds 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid significantly better than N-acetylneuraminic acid, whereas Sn prefers the latter structure. These results indicate that the interactions of MAG and Sn are mainly with sialic acid and that additional contacts with the subterminal galactose and N-acetylglucosamine residues also contribute to the binding strength, although to a lesser degree.
Journal of Neurochemistry, 1992
Po, the most abundant glycoprotein of PNS myelin, is a homophilic and heterophilic adhesion molecule. Po is known to contain a glycoform population that expresses the L2/HNK-1 carbohydrate epitope found on other neural adhesion molecules, and to be functionally implicated centrally in neural cell adhesion and neurite outgrowth. This carbohydrate epitope has been characterized previously from glycolipid structures and contains a sulphated glucuronic acid residue. However, the L2/HNK-1 carbohydrate epitope has not been characterized in glycoproteins. Because Po possesses only one glycosylation sequon, the number of Po glycoforms is equal to the heterogeneity of the glycan species. Here we report that the carbohydrate analysis of L2/HNK-1 -reactive Po showed the presence of anionic structures containing sialic
Soluble intercellular adhesion molecule-1 (sICAM-1): an overview
European cytokine network, 2004
Soluble intercellular adhesion molecule-1 (sICAM-1) represents a circulating form of ICAM-1 that is constitutively expressed or is inducible on the cell surface of different cell lines. It serves as a counter-receptor for the lymphocyte function-associated antigen (LFA-1). Interaction between ICAM-1, present on endothelial cells, and LFA-1 facilitates leukocyte adhesion and migration across the endothelium. ICAM-1 and its circulating form have been implicated in the development of any number of diseases.
Role of siglecs and related glycan-binding proteins in immune responses and immunoregulation
Journal of Allergy and Clinical Immunology, 2015
Eukaryotic cells and extracellular material are heavily decorated by various glycans, yet the understanding of the structure and function of these moieties lags behind our understanding of nucleic acids, lipids and proteins. Recent years have seen a tremendous acceleration of understanding in the field of glycobiology, revealing many intricacies and functional contributions that were previously poorly understood or even unrecognized. This review highlights several topics relevant to glycoimmunology, where mammalian and pathogen-derived glycans displayed on glycoproteins and other scaffolds are recognized by specific glycan-binding proteins (GBPs), leading to a variety of pro-and anti-inflammatory cellular responses. The focus for this review is mainly on two families of GBPs, siglecs and selectins, that are involved in multiple steps of the immune response, including distinguishing pathogens from self, cell trafficking to sites of inflammation, fine-tuning of immune responses leading to activation or tolerance, and regulation of cell survival. Importantly for the clinician, accelerated rates of discovery in the field of glycoimmunology are being translated into innovative medicinal approaches that harness the interaction of glycans and GBPs to the benefit of the host, and may soon lead to novel diagnostics and therapeutics.