scholarly journals The role of sialated glycoproteins in endocytosis, permeability and transmural passage in the myeloid endothelium.

1979 ◽  
Vol 27 (8) ◽  
pp. 1174-1176 ◽  
Author(s):  
P P De Bruyn
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Charge Distribution ◽  
Surface Modifications ◽  
Low Ph ◽  
Cell Passage ◽  
Colloidal Iron ◽  
Endothelial Cell Surface ◽  
Anionic Charge

Changes in the anionic charge distribution at the luminal face of the endothelium of the sinusoids of the bone marrow have been studied at sites of endocytosis by large bristle coated vesicles and at the sites of molecular permeability through diaphragmed fenestrae. The anionic charge distribution has also been studied at the abluminal aspect of these vessels at sites of transmural blood cell passage. Cationic surface markers such as colloidal iron, native ferritin and polycationic ferritin used at low pH, 1.8, and the use of neuraminidase show that the nonmodified endothelial cell surface has exposed sialic acid groups, which are absent at the sites of these functional specializations. Polycationic ferritin binding over a range of pH levels indicates the prsence of another species of anionic materials present at both the nonmodified cell surface and at the sites of the cell surface modifications. This second group of anionic compounds is neuraminidase resistant and has a pKa higher than that of sialic acid (pKa:2.6).

scholarly journals Nonrandom distribution of sialic acid over the cell surface of bristle-coated endocytic vesicles of the sinusoidal endothelium cells.

1978 ◽  
Vol 78 (2) ◽  
pp. 379-389 ◽  
Author(s):  
P P De Bruyn ◽  
S Michelson ◽  
R P Becker
Keyword(s):  
Endothelial Cell ◽  
Sialic Acid ◽  
Cell Surface ◽  
Free Cell ◽  
Luminal Surface ◽  
Colloidal Iron ◽  
Endothelial Cell Surface ◽  
Protein Tracers ◽  
Anionic Charge ◽  
Ph Range

Previous studies with protein tracers have shown that the luminal surface of the vascular endothelium of the bone marrow is endocytic. The endocytosis occurs through the formation of large bristle-coated vesicles (LCV). The anionic charge distribution in this process was examined at the luminal surface of the endothelial cell, At pH 1.8, colloidal iron (CI), native ferritin, and polycationic ferritin (PCF) are bound by the luminal surface of the endothelial cell, but not at the sites of LCV formation. PCF used over a pH range of 1.8--7.2 (CI is unstable at higher pH levels) revealed LCV binding of this agent in increasing manner from pH 3.5 upwards. PCF binding at low pH (1.8) at the endothelial cell surface was markedly reduced by neuraminidase. Neuraminidase did not reduce PCF binding by the endothelial cell surface nor by the LCV at higher pH levels. It is concluded that the luminal surface of the endothelial cell has exposed sialic acid groups which are absent or significantly diminished at endocytic sites. The free surface of the endothelial cells as well as the sites of endocytosis have, in addition, anionic material with a pKa higher than that of sialic acid (pKa 2.6). These anionic materials may be different at the sites of endocytosis as compared to those present at the free cell surface.

scholarly journals Changes in the random distribution of sialic acid at the surface of the myeloid sinusoidal endothelium resulting from the presence of diaphragmed fenestrae.

1979 ◽  
Vol 82 (3) ◽  
pp. 708-714 ◽  
Author(s):  
P P De Bruyn ◽  
S Michelson
Keyword(s):  
Endothelial Cell ◽  
Sialic Acid ◽  
Cell Surface ◽  
Random Distribution ◽  
Colloidal Iron ◽  
Neuraminidase Treatment ◽  
Endothelial Cell Surface ◽  
Anionic Charge ◽  
Sinusoidal Endothelium ◽  
Ph Range

Diaphragmed fenestrae (DF) are sites of increased vascular permeability. The anionic charge distribution at the luminal aspect of the DF of the endothelium of the bone marrow vessels has been studied after aldehyde fixation by means of colloidal iron (CI), native ferritin (NF), and polycationic ferritin (PCF). At pH 1.8, these cationic agents are bound by the nonmodified luminal endothelial cell surface but not at the sites of the DF. PCF was used over a pH range of 1.8--7.2 (CI is unstable at higher pH levels, whereas NF which has a pI of 4.5 is anionic above this point). PCF shows increased binding at the DF from pH 3.5 upwards. PCF binding at pH 1.8 at the nonmodified luminal cell surface is significantly diminished by neuraminidase treatment which, however, does not perceptibly reduce PCF binding at the higher pH levels. It is concluded that there are exposed sialic acid groups at the lunimal cell surface which are absent or significantly fewer at the sites of the DF, whereas other anionic materials possibly with a pKa higher than that of sialic acid (pKa 2.6) are present both at the DF and at the nonmodified endothelial cell surface.

scholarly journals The Role of Sialic Acids in the Establishment of Infections by Pathogens, With Special Focus on Leishmania

2021 ◽  
Vol 11 ◽  
Author(s):  
Tainá Cavalcante ◽  
Mariana Medina Medeiros ◽  
Simon Ngao Mule ◽  
Giuseppe Palmisano ◽  
Beatriz Simonsen Stolf
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Host Cell ◽  
Functional Diversity ◽  
Sialic Acids ◽  
Cellular Communication ◽  
Special Focus ◽  
Functional Studies ◽  
Sialic Acid Binding

Carbohydrates or glycans are ubiquitous components of the cell surface which play crucial biological and structural roles. Sialic acids (Sias) are nine-carbon atoms sugars usually present as terminal residues of glycoproteins and glycolipids on the cell surface or secreted. They have important roles in cellular communication and also in infection and survival of pathogens. More than 20 pathogens can synthesize or capture Sias from their hosts and incorporate them into their own glycoconjugates and derivatives. Sialylation of pathogens’ glycoconjugates may be crucial for survival inside the host for numerous reasons. The role of Sias in protozoa such as Trypanosoma and Leishmania was demonstrated in previous studies. This review highlights the importance of Sias in several pathogenic infections, focusing on Leishmania. We describe in detail the contributions of Sias, Siglecs (sialic acid binding Ig-like lectins) and Neuraminidase 1 (NEU 1) in the course of Leishmania infection. A detailed view on the structural and functional diversity of Leishmania-related Sias and host-cell receptors will be provided, as well as the results of functional studies performed with different Leishmania species.

On the ultrastructural localization of cell surface sialyl residues versus anionic sites

1978 ◽  
Vol 36 (2) ◽  
pp. 294-295
Author(s):  
E. Skutelsky ◽  
S. Hoglund ◽  
B. Morein ◽  
E.A. Bayer
Keyword(s):  
Cell Surface ◽  
Ferric Hydroxide ◽  
Ultrastructural Localization ◽  
Anionic Sites ◽  
Successive Treatment ◽  
Coulombic Interaction ◽  
Thin Sections ◽  
Anionic Charge ◽  
Specific Localization

Membrane-associated sialic acids(SA) are considered to have an important role in a variety of cell sur ace interactions. Visualization of SA sites and their ultrastructural quantitative evaluation have heverally been based on the coulombic interaction between anionic sites of sialyl carboxyl groups with polycationic,electron dense markers, e.g. colloidal ferric hydroxide or cationized ferritin(CF). We have recently demonstrated an alternative method, whereby periodate-induced biotinylation (PIB) of unfixed cells can be used for specific localization of SA in thin sections by ferritin-conjugated avidin (FAv). It was further shown that PIB does not affect the surface anionic charge, since the latter is still available to CF-staining. In order to determine the role of anionic sites on the distribution and configuration of cell surface sialoglycoproteins and or sialoglycolipids, we have compared the topographic distribution of attached FAv or CF particles on normal and pathological blood cells,following successive treatment with sodium periodate and biotin hydrazide.

Role of sialic acid in the maintenance of cell surface rigidity

1975 ◽  
Vol 31 (9) ◽  
pp. 1075-1077 ◽  
Author(s):  
P. K. Ray ◽  
S. Chatterjee
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Surface Rigidity

Role of Endothelial Cell Surface Heparin-like Polysaccharides

1989 ◽  
Vol 556 (1 Heparin and R) ◽  
pp. 81-94 ◽  
Author(s):  
JAMES A. MARCUM ◽  
ROBERT D. ROSENBERG
Keyword(s):  
Endothelial Cell ◽  
Cell Surface ◽  
Endothelial Cell Surface
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