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 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 Surface charge distribution on the endothelial cell of liver sinusoids.

1984 ◽  
Vol 99 (2) ◽  
pp. 639-647 ◽  
Author(s):  
L Ghitescu ◽  
A Fixman
Keyword(s):  
Endothelial Cell ◽  
Cell Surface ◽  
Liver Sinusoid ◽  
Electron Microscopic ◽  
Coated Pits ◽  
Endothelial Cell Surface ◽  
Liver Sinusoids ◽  
Surface Charge Distribution ◽  
Cationic Residues

The topography of the charged residues on the endothelial cell surface of liver sinusoid capillaries was investigated by using electron microscopic tracers of different size and charge. The tracers used were native ferritin (pl 4.2-4.7) and its cationized (pl 8.4) and anionized (pl 3.7) derivatives, BSA coupled to colloidal gold (pl of the complex 5.1), hemeundecapeptide (pl 4.85), and alcian blue (pl greater than 10). The tracers were either injected in vivo or perfused in situ through the portal vein of the mouse liver. In some experiments, two tracers of opposite charge were sequentially perfused with extensive washing in between. The liver was processed for electron microscopy and the binding pattern of the injected markers was recorded. The electrostatic nature of the tracer binding was assessed by perfusion with high ionic strength solutions, by aldehyde quenching of the plasma membrane basic residues, and by substituting the cell surface acidic moieties with positively charged groups. Results indicate that the endothelial cells of the liver sinusoids expose on their surface both cationic and anionic residues. The density distribution of these charged groups on the cell surface is different. While the negative charge is randomly and patchily scattered all over the membrane, the cationic residues seem to be accumulated in coated pits. The charged groups co-exist in the same coated pit and bind the opposite charged macromolecule. It appears that the fixed positive and negative charges of the coated pit glycocalyx are mainly segregated in space. The layer of basic residues is located at 20-30-nm distance of the membrane, while most of the negative charges lie close to the external leaflet of the plasmalemma.

The ultrastructural basis of endothelial cell surface functions

Biorheology ◽  
1984 ◽  
Vol 21 (1-2) ◽  
pp. 155-170 ◽  
Author(s):  
Una S. Ryan ◽  
James W. Ryan
Keyword(s):  
Endothelial Cell ◽  
Cell Surface ◽  
Endothelial Cell Surface

scholarly journals Leukocyte adhesion is governed by endolysosomal two pore channel 2 (TPC2)

2021 ◽  
Author(s):  
Jonas Goretzko ◽  
Nicole Heitzig ◽  
Katharina Thomas ◽  
Einar Kleinhans Krogsaeter ◽  
Johannes Nass ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Cell Surface ◽  
Leukocyte Adhesion ◽  
Leukocyte Recruitment ◽  
Pore Channel ◽  
Initial Contact ◽  
Surface Receptors ◽  
Endothelial Cell Surface ◽  
Late Endosomes ◽  
Endothelial Functions

In response to pro-inflammatory challenges including pathogenic attack and tissue damage, the endothelial cell surface is rearranged to present leukocyte-engaging cell surface receptors. The initial contact needed for leukocyte tethering and rolling is mediated via adhesion demand-driven exocytosis of Weibel-Palade bodies (WPB) that contain the leukocyte receptor P-selectin together with the stabilizing co-factor CD63. We found that diminished expression of the endolysosomal non-selective cation channel TPC2 or inhibition of TPC2-mediated Ca2+-release via trans-Ned 19 led to reduced endolysosomal Ca2+ efflux, and blocked transfer of CD63 from late endosomes/lysosomes (LEL) to WPB, and a concomitant loss of P-selectin on the endothelial cell surface. Accordingly, P-selectin-mediated leukocyte recruitment to trans-Ned 19-treated HUVEC under flow was significantly reduced without disturbing VWF exocytosis. Our findings establish the endolysosome-related TPC2 Ca2+ channel as a key element in the maintenance of proper endothelial functions and a potential pharmacological target in the control of inflammatory leukocyte recruitment.

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