Stimulation of receptor-mediated low density lipoprotein endocytosis in neuraminidase-treated cultured bovine aortic endothelial cells

Eugene A Sprague, M. Moser, E. H. Edwards, C. J. Schwartz

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Sialic acids, occupying a terminal position in cell surface glycoconjugates, are major contributors to the net negative charge of the vascular endothelial cell surface. As integral membrane glycoproteins, LDL receptors also bear terminal sialic acid residues. Pretreatment of near-confluent, cultured bovine aortic endothelial cells (BAEC) with neuraminidase (50 mU/ml, 30 min, 37°C) stimulated a significant increase in receptor-mediated 125I-LDL internalization and degradation relative to PBS-treated control cells. Binding studies at 4°C revealed an increased affinity of LDL receptor sites on neuraminidase-treated cells compared to control BAEC (6.9 vs. 16.2 nM/106 BAEC) without a change in receptor site number. This enhanced LDL endocytosis in neuraminidase-treated cells was dependent upon the enzymatic activity of the neuraminidase and the removal of sialic acid from the cell surface. Furthermore, enhanced endocytosis due to enzymatic alteration of the 125I-LDL molecules was excluded. In contrast to BAEC, neuraminidase pretreatment of LDL receptor-upregulated cultured normal human fibroblast resulted in an inhibition of 125I-LDL binding, internalization, and degradation. Specifically, a significant inhibition in 125I-LDL internalization was observed at 1 hr after neuraminidase treatment, which was associated with a decrease in the number of cell surface LDL receptor sites. Like BAEC, neuraminidase pretreatment of human umbilical vein endothelial cells resulted in enhanced receptor-mediated 125I-LDL endocytosis. These results indicate that sialic acid associated with either adjacent endothelial cell surface molecules or the endothelial LDL receptor itself may modulate LDL receptor-mediated endocytosis and suggest that this regulatory mechanism may be of particular importance to endothelial cells.

Original languageEnglish (US)
Pages (from-to)251-262
Number of pages12
JournalJournal of Cellular Physiology
Volume137
Issue number2
StatePublished - 1988

Fingerprint

LDL Receptors
Endothelial cells
Neuraminidase
Endocytosis
LDL Lipoproteins
Endothelial Cells
N-Acetylneuraminic Acid
Sialic Acids
Cells
Glycoconjugates
Degradation
Membrane Glycoproteins
Human Umbilical Vein Endothelial Cells
Cell Surface Receptors
Molecules
Fibroblasts
oxidized low density lipoprotein

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

Cite this

Stimulation of receptor-mediated low density lipoprotein endocytosis in neuraminidase-treated cultured bovine aortic endothelial cells. / Sprague, Eugene A; Moser, M.; Edwards, E. H.; Schwartz, C. J.

In: Journal of Cellular Physiology, Vol. 137, No. 2, 1988, p. 251-262.

Research output: Contribution to journalArticle

Sprague, Eugene A ; Moser, M. ; Edwards, E. H. ; Schwartz, C. J. / Stimulation of receptor-mediated low density lipoprotein endocytosis in neuraminidase-treated cultured bovine aortic endothelial cells. In: Journal of Cellular Physiology. 1988 ; Vol. 137, No. 2. pp. 251-262.
@article{5905a43fa8fe4923980e5c20d7a3627d,
title = "Stimulation of receptor-mediated low density lipoprotein endocytosis in neuraminidase-treated cultured bovine aortic endothelial cells",
abstract = "Sialic acids, occupying a terminal position in cell surface glycoconjugates, are major contributors to the net negative charge of the vascular endothelial cell surface. As integral membrane glycoproteins, LDL receptors also bear terminal sialic acid residues. Pretreatment of near-confluent, cultured bovine aortic endothelial cells (BAEC) with neuraminidase (50 mU/ml, 30 min, 37°C) stimulated a significant increase in receptor-mediated 125I-LDL internalization and degradation relative to PBS-treated control cells. Binding studies at 4°C revealed an increased affinity of LDL receptor sites on neuraminidase-treated cells compared to control BAEC (6.9 vs. 16.2 nM/106 BAEC) without a change in receptor site number. This enhanced LDL endocytosis in neuraminidase-treated cells was dependent upon the enzymatic activity of the neuraminidase and the removal of sialic acid from the cell surface. Furthermore, enhanced endocytosis due to enzymatic alteration of the 125I-LDL molecules was excluded. In contrast to BAEC, neuraminidase pretreatment of LDL receptor-upregulated cultured normal human fibroblast resulted in an inhibition of 125I-LDL binding, internalization, and degradation. Specifically, a significant inhibition in 125I-LDL internalization was observed at 1 hr after neuraminidase treatment, which was associated with a decrease in the number of cell surface LDL receptor sites. Like BAEC, neuraminidase pretreatment of human umbilical vein endothelial cells resulted in enhanced receptor-mediated 125I-LDL endocytosis. These results indicate that sialic acid associated with either adjacent endothelial cell surface molecules or the endothelial LDL receptor itself may modulate LDL receptor-mediated endocytosis and suggest that this regulatory mechanism may be of particular importance to endothelial cells.",
author = "Sprague, {Eugene A} and M. Moser and Edwards, {E. H.} and Schwartz, {C. J.}",
year = "1988",
language = "English (US)",
volume = "137",
pages = "251--262",
journal = "Journal of Cellular Physiology",
issn = "0021-9541",
publisher = "Wiley-Liss Inc.",
number = "2",

}

TY - JOUR

T1 - Stimulation of receptor-mediated low density lipoprotein endocytosis in neuraminidase-treated cultured bovine aortic endothelial cells

AU - Sprague, Eugene A

AU - Moser, M.

AU - Edwards, E. H.

AU - Schwartz, C. J.

PY - 1988

Y1 - 1988

N2 - Sialic acids, occupying a terminal position in cell surface glycoconjugates, are major contributors to the net negative charge of the vascular endothelial cell surface. As integral membrane glycoproteins, LDL receptors also bear terminal sialic acid residues. Pretreatment of near-confluent, cultured bovine aortic endothelial cells (BAEC) with neuraminidase (50 mU/ml, 30 min, 37°C) stimulated a significant increase in receptor-mediated 125I-LDL internalization and degradation relative to PBS-treated control cells. Binding studies at 4°C revealed an increased affinity of LDL receptor sites on neuraminidase-treated cells compared to control BAEC (6.9 vs. 16.2 nM/106 BAEC) without a change in receptor site number. This enhanced LDL endocytosis in neuraminidase-treated cells was dependent upon the enzymatic activity of the neuraminidase and the removal of sialic acid from the cell surface. Furthermore, enhanced endocytosis due to enzymatic alteration of the 125I-LDL molecules was excluded. In contrast to BAEC, neuraminidase pretreatment of LDL receptor-upregulated cultured normal human fibroblast resulted in an inhibition of 125I-LDL binding, internalization, and degradation. Specifically, a significant inhibition in 125I-LDL internalization was observed at 1 hr after neuraminidase treatment, which was associated with a decrease in the number of cell surface LDL receptor sites. Like BAEC, neuraminidase pretreatment of human umbilical vein endothelial cells resulted in enhanced receptor-mediated 125I-LDL endocytosis. These results indicate that sialic acid associated with either adjacent endothelial cell surface molecules or the endothelial LDL receptor itself may modulate LDL receptor-mediated endocytosis and suggest that this regulatory mechanism may be of particular importance to endothelial cells.

AB - Sialic acids, occupying a terminal position in cell surface glycoconjugates, are major contributors to the net negative charge of the vascular endothelial cell surface. As integral membrane glycoproteins, LDL receptors also bear terminal sialic acid residues. Pretreatment of near-confluent, cultured bovine aortic endothelial cells (BAEC) with neuraminidase (50 mU/ml, 30 min, 37°C) stimulated a significant increase in receptor-mediated 125I-LDL internalization and degradation relative to PBS-treated control cells. Binding studies at 4°C revealed an increased affinity of LDL receptor sites on neuraminidase-treated cells compared to control BAEC (6.9 vs. 16.2 nM/106 BAEC) without a change in receptor site number. This enhanced LDL endocytosis in neuraminidase-treated cells was dependent upon the enzymatic activity of the neuraminidase and the removal of sialic acid from the cell surface. Furthermore, enhanced endocytosis due to enzymatic alteration of the 125I-LDL molecules was excluded. In contrast to BAEC, neuraminidase pretreatment of LDL receptor-upregulated cultured normal human fibroblast resulted in an inhibition of 125I-LDL binding, internalization, and degradation. Specifically, a significant inhibition in 125I-LDL internalization was observed at 1 hr after neuraminidase treatment, which was associated with a decrease in the number of cell surface LDL receptor sites. Like BAEC, neuraminidase pretreatment of human umbilical vein endothelial cells resulted in enhanced receptor-mediated 125I-LDL endocytosis. These results indicate that sialic acid associated with either adjacent endothelial cell surface molecules or the endothelial LDL receptor itself may modulate LDL receptor-mediated endocytosis and suggest that this regulatory mechanism may be of particular importance to endothelial cells.

UR - http://www.scopus.com/inward/record.url?scp=0024241415&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0024241415&partnerID=8YFLogxK

M3 - Article

C2 - 3192617

AN - SCOPUS:0024241415

VL - 137

SP - 251

EP - 262

JO - Journal of Cellular Physiology

JF - Journal of Cellular Physiology

SN - 0021-9541

IS - 2

ER -