scholarly journals Expression of sialic acid on the alveolar surface of adult and fetal human lungs.

1986 ◽  
Vol 34 (6) ◽  
pp. 811-816 ◽  
Author(s):  
T Faraggiana ◽  
D Villari ◽  
J Jagirdar ◽  
J Patil
Keyword(s):  
Sialic Acid ◽  
Light And Electron Microscopy ◽  
Fetal Lung ◽  
Peanut Lectin ◽  
Neuraminidase Treatment ◽  
Human Lungs ◽  
Type Ii Pneumocytes ◽  
Respiratory Tree ◽  
Binding Lectin ◽  
Alveolar Surface

Lung alveoli are coated by a thin layer of extracellular material rich in anionic charges. The nature of this acid layer and its relationship to the phospholipid surfactant are not known. We investigated the possible presence of sialic acid groups by light and electron microscopy in tissues from normal fetal and adult lungs, using neuraminidase treatment followed by staining with the galactose-binding lectin from peanut, labeled with peroxidase. Our results showed that adult lung does not bear peanut lectin-reactive sites but that a very thin and distinct reactive layer becomes evident after neuraminidase treatment, especially on type II pneumocytes. In fetal lung, the entire surface of the developing respiratory tree is outlined by a strongly peanut lectin-reactive layer even if neuraminidase digestion is not performed. We conclude that the acid coat of the alveolar lining is in part composed of sialic acid residues and that sialic acid is added to the fetal lung as the alveoli mature.

scholarly journals Porcine Arterivirus Infection of Alveolar Macrophages Is Mediated by Sialic Acid on the Virus

2004 ◽  
Vol 78 (15) ◽  
pp. 8094-8101 ◽  
Author(s):  
Peter L. Delputte ◽  
Hans J. Nauwynck
Keyword(s):  
Sialic Acid ◽  
Alveolar Macrophages ◽  
Sialic Acids ◽  
Respiratory Syndrome Virus ◽  
Specific Monoclonal Antibody ◽  
Neuraminidase Treatment ◽  
Acid Binding Protein ◽  
Sialic Acid Binding ◽  
High Mannose ◽  
Binding Lectin

ABSTRACT Recently, we showed that porcine sialoadhesin (pSn) mediates internalization of the arterivirus porcine reproductive and respiratory syndrome virus (PRRSV) in alveolar macrophages (Vanderheijden et al., J. Virol. 77:8207-8215, 2003). In rodents and humans, sialoadhesin, or Siglec-1, has been described as a macrophage-restricted molecule and to specifically bind sialic acid moieties. In the current study, we investigated whether pSn is a sialic acid binding protein and, whether so, whether this property is important for its function as a PRRSV receptor. Using untreated and neuraminidase-treated sheep erythrocytes, we showed that pSn binds sialic acid. Furthermore, pSn-specific monoclonal antibody 41D3, which blocks PRRSV infection, inhibited this interaction. PRRSV attachment to and infection of porcine alveolar macrophages (PAM) were both shown to be dependent on the presence of sialic acid on the virus: neuraminidase treatment of virus but not of PAM blocked infection and reduced attachment. Enzymatic removal of all N-linked glycans on the virus with N-glycosidase F reduced PRRSV infection, while exclusive removal of nonsialylated N-linked glycans of the high-mannose type with endoglycosidase H had no significant effect. Free sialyllactose and sialic acid containing (neo)glycoproteins reduced infection, while lactose and (neo)glycoproteins devoid of sialic acids had no significant effect. Studies with linkage-specific neuraminidases and lectins indicated that α2-3- and α2-6-linked sialic acids on the virion are important for PRRSV infection of PAM. From these results, we conclude that pSn is a sialic acid binding lectin and that interactions between sialic acid on the PRRS virion and pSn are essential for PRRSV infection of PAM.

scholarly journals Purification and use of limulin: a sialic acid-specific lectin.

1982 ◽  
Vol 30 (9) ◽  
pp. 938-946 ◽  
Author(s):  
V Muresan ◽  
V Iwanij ◽  
Z D Smith ◽  
J D Jamieson
Keyword(s):  
Sialic Acid ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Light And Electron Microscopy ◽  
Sodium Dodecyl ◽  
Limulus Polyphemus ◽  
Pancreatic Acinar Cells ◽  
Renal Tubules ◽  
Neuraminidase Treatment ◽  
Horse Red Blood Cells

A simple and rapid method for the isolation of the sialic acid-specific lectin, Limulus polyphemus hemagglutinin (LPA), from the hemolymph of Limulus polyphemus is described. Declotted hemolymph is adsorbed to an affinity chromatographic column consisting of hog gastric mucin glycopeptides coupled to agarose and LPA is eluted in a single step with a Ca2+-free buffer, giving an apparent purification of approximately 25,000-fold. The eluted material is homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing and consists of identical subunits each of 29,000 daltons. Hemagglutination inhibition studies with horse red blood cells indicate specificity of LPA for N-acetyl- and N-glycolylneuraminic acid; binding is Ca2+ -dependent and abolished by neuraminidase treatment. LPA was covalently coupled to rhodamine and to horseradish peroxidase for use in detection of sialoglycoconjugates on cells and tissues by light and electron microscopy. Examples of the use of LPA for detection of sialoglycoconjugates in rat renal tubules and glomeruli, blood vessels in rat pancreas, and on horse red blood cells are shown. The procedures described here should prove useful as a cytochemical probe for detection of sialoglycoconjugates in a variety of systems. An accompanying article utilizes these probes for the detection of sialoglycoconjugates on the plasmalemma of adult and differentiating rat pancreatic acinar cells.

scholarly journals The Importance of Platelet Glycoside Residues in the Haemostasis of Patients with Immune Thrombocytopaenia

2021 ◽  
Vol 10 (8) ◽  
pp. 1661
Author(s):  
Andrés Ramírez-López ◽  
María Teresa Álvarez Román ◽  
Elena Monzón Manzano ◽  
Paula Acuña ◽  
Elena G. Arias-Salgado ◽  
...  
Keyword(s):  
Platelet Count ◽  
Sialic Acid ◽  
Healthy Controls ◽  
Caspase Activity ◽  
Antibody Dependent Cellular Cytotoxicity ◽  
Activation Markers ◽  
Platelet Surface ◽  
Mannose Binding ◽  
Transversal Study ◽  
Binding Lectin

Loss of sialic acid from the carbohydrate side chains of platelet glycoproteins can affect platelet clearance, a proposed mechanism involved in the etiopathogenesis of immune thrombocytopaenia (ITP). We aimed to assess whether changes in platelet glycosylation in patients with ITP affected platelet counts, function, and apoptosis. This observational, prospective, and transversal study included 82 patients with chronic primary ITP and 115 healthy controls. We measured platelet activation markers and assayed platelet glycosylation and caspase activity, analysing samples using flow cytometry. Platelets from patients with ITP with a platelet count <30 × 103/µL presented less sialic acid. Levels of α1,6-fucose (a glycan residue that can directly regulate antibody-dependent cellular cytotoxicity) and α-mannose (which can be recognised by mannose-binding-lectin and activate the complement pathway) were increased in the platelets from these patients. Platelet surface exposure of other glycoside residues due to sialic acid loss inversely correlated with platelet count and the ability to be activated. Moreover, loss of sialic acid induced the ingestion of platelets by human hepatome HepG2 cells. Changes in glycoside composition of glycoproteins on the platelets’ surface impaired their functional capacity and increased their apoptosis. These changes in platelet glycoside residues appeared to be related to ITP severity.

scholarly journals Effects of pronase and neuraminidase treatment on a myelin-associated glycoprotein in developing brain

1976 ◽  
Vol 156 (1) ◽  
pp. 143-150 ◽  
Author(s):  
R H Quarles
Keyword(s):  
Molecular Weight ◽  
Sialic Acid ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Apparent Molecular Weight ◽  
Weight Class ◽  
Developmental Difference ◽  
Adult Rats ◽  
Neuraminidase Treatment

Rats (14 days old) were injected with [14c]fucose and young adult rats with [3H]fucose in order to label the myelin-associated glycoproteins. As previously reported, the major [14C]fucose-labelled glycoprotein in the immature myelin had a higher apparent molecular weight on sodium dodecyl sulphate/polyacrylamide gels that the [3H]fucose-labelled glycoprotein in mature myelin. This predominant doubly labelled glycoprotein component was partially purified by preparative gel electrophoresis and converted to glycopeptides by extensive Pronase digestion. Gel filtration on Sephadex G-50 separated the glycopeptides into several clases, which were designted A,B, C AND D, from high to low molecular weight. The 14C-labelled glycopeptides from immature myeline were enriched in the highest-molecular-weight class A relative to the 3H-labelled glycopeptides from mature myelin. Neuraminidase treatment of the glycoprotein before Pronase digestion greatly decreased the proportion of glycopeptides fractionating in the higher-molecular-weight classes and largely eliminated the developmental differences that were apparent by gel filtration. However, neuraminidase treatment did not decrease the magnitude of the developmental difference revealed by electrophoresing the intact glycoprotein on sodium dodecyl sulphate gels, although it did decrease the apparent molecular weight of the glycoprotein from both the 15-day-old and adult rats by an amount comparable in magnitude to that developmental difference. The results from gel filtration of glycopeptides indicate that there is a higher content of large molecular weight, sialic acid-rich oligosaccharide units in the glycoprotein of immature myelin. However, the higher apparent molecular weight for the glycoprotein from 15-day-old rats on sodium dodcyl sulphate gels is not due primarily to its higher sialic acid content.

scholarly journals Sialic acid-Dependent Binding and Viral Entry of SARS-CoV-2

2021 ◽  
Author(s):  
Linh Nguyen ◽  
Kelli McCord ◽  
Duong Bui ◽  
Kim Bouwman ◽  
Elena Kitova ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Receptor Binding ◽  
Viral Entry ◽  
Receptor Binding Domain ◽  
Artificial Membrane ◽  
Neuraminidase Treatment ◽  
S Protein ◽  
Knock Out

Abstract Emerging evidence suggests that host glycans influence infection by SARS-CoV-2. Here, we reveal that the receptor-binding domain (RBD) of the spike (S)-protein on SARS-CoV-2 recognizes oligosaccharides containing sialic acid (SA), with preference for the oligosaccharide of monosialylated gangliosides. Gangliosides embedded within an artificial membrane also bind the RBD. The monomeric affinities (Kd = 100-200 μM) of gangliosides for the RBD are similar to heparan sulfate, another negatively charged glycan ligand of the RBD proposed as a viral co-receptor. RBD binding and infection of SARS-CoV-2 pseudotyped lentivirus to ACE2-expressing cells is decreased upon depleting cell surface SA level using three approaches: sialyltransferase inhibition, genetic knock-out of SA biosynthesis, or neuraminidase treatment. These effects on RBD binding and pseudotyped viral entry are recapitulated with pharmacological or genetic disruption of glycolipid biosynthesis. Together, these results suggest that sialylated glycans, specifically glycolipids, facilitate viral entry of SARS-CoV-2.

Neuraminidase selectively enhances transient Ca2+ current in cardiac myocytes

1989 ◽  
Vol 256 (6) ◽  
pp. C1267-C1272 ◽  
Author(s):  
H. F. Yee ◽  
J. N. Weiss ◽  
G. A. Langer
Keyword(s):  
Sialic Acid ◽  
Ventricular Myocytes ◽  
Calcium Content ◽  
Selective Inhibition ◽  
Myocardial Cell ◽  
Ca Channel ◽  
Neuraminidase Treatment ◽  
Membrane Function ◽  
Channel Current ◽  
Current Exposure

Sialic acid, an anionic sugar moiety found peripherally on membrane glycoconjugates, is specifically hydrolyzed from the cell surface by neuraminidase. Because neuraminidase has previously been demonstrated to augment myocardial cell calcium content, the effects of neuraminidase on Ca channel function were studied on voltage-clamped guinea pig ventricular myocytes. In 25-50% of cells, neuraminidase treatment (0.12 U/ml for 20 min) enhanced current through the transient (T) Ca channel by 304 +/- 35% without significantly altering the magnitude of the long-lasting (L) Ca channel current. Exposure to neuraminidase did not affect the voltage dependence of activation or inactivation, nor did it affect the selective inhibition of the T-channel current by amiloride or the L-channel current by nifedipine. After neuraminidase treatment, the T-channel current inactivated more rapidly (time constant decreasing from 8.9 +/- 0.9 to 7.7 +/- 0.6 ms), whereas there was no change in the rate of inactivation of the L-channel current. Neuraminidase treatment removed approximately 20% of the total cellular sialic acid. These results indicate that neuraminidase treatment selectively modulates the function of the T Ca channel in ventricular myocytes, possibly through removal of sarcolemmal sialic acid, suggesting that glycosylation of membrane macromolecules may influence membrane function.

Electrophoretic and Chemical Characterization of the Charged Groups at the Surface of Murine CL3 Ascites Leukaemia Cells

1969 ◽  
Vol 4 (2) ◽  
pp. 289-298
Author(s):  
P. D. WARD ◽  
E. J. AMBROSE
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Chemical Characterization ◽  
Surface Protein ◽  
Subsequent Treatment ◽  
Surface Proteins ◽  
Carboxyl Groups ◽  
Neuraminidase Treatment ◽  
Ionic Nature ◽  
Ph Range

The electrophoretic characteristics of the murine CL3 ascites tumour were investigated. Treatment of the cells with formaldehyde raised the electrophoretic mobility (E.P.M.) from - 1.06 to - 1.28 µ/sec/V/cm; subsequent treatment with diazomethane reduced their mobility to zero. The E.P.M. of the diazomethane-treated cells did not alter over the pH range 3.0-8.0. This proved that the only ionic groups at this cell surface were amino and carboxyl groups. The absence of phosphate groups, another possibility, was confirmed by the lack of calcium-ion binding from 10 mM Ca2+ solutions. Neuraminidase treatment reduced the E.P.M. from -1.06 to -0.55 µ/sec/V/cm and free sialic acid was identified in the enzyme supernatant. Subsequent treatment of the cells with formaldehyde raised the mobility to -1.22 µ/sec/V/cm indicating that the change in E.P.M. on neuraminidase treatment was not due solely to the removal of the carboxyl groups of sialic acid but also to a change in the ionic nature of the surface. This change is ascribed to a change in the conformation of the surface protein. The reason for this change and a suggestion for the possible role of sialic acid at the cell surface are mentioned. Treatment of the cells with trypsin did not affect the viable cells in any way, suggesting that the surface proteins lack the basic amino acids lysine and arginine. Pronase treatment served only to show that much of the sialic acid was bound to protein; the total amount was not determined.

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