Apo E-mediated uptake and degradation of normal very low density lipoproteins by human monocyte/macrophages: A saturable pathway distinct from the LDL receptor

1985 ◽  
Vol 126 (1) ◽  
pp. 578-586 ◽  
Author(s):  
Patsy Wang-Iverson ◽  
Henry N. Ginsberg ◽  
Linda A. Peteanu ◽  
Ngoc-Anh Le ◽  
W.Virgil Brown
Keyword(s):  
Ldl Receptor ◽  
Human Monocyte ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Apo E

scholarly journals Degradation of lipoproteins by human monocyte-derived macrophages. Evidence for two distinct processes for the degradation of abnormal very-low-density lipoprotein from subjects with type III hyperlipidaemia

1984 ◽  
Vol 218 (1) ◽  
pp. 101-111 ◽  
Author(s):  
A K Soutar ◽  
B L Knight
Keyword(s):  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Normal Subjects ◽  
Peritoneal Macrophages ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Free Medium ◽  
Very Low Density Lipoproteins ◽  
Type Iii

Human blood monocyte-derived macrophages that had been cultured in medium containing human serum for 7 days degraded the abnormal very-low-density lipoproteins (VLDL) from the plasma of subjects with type III hyperlipoproteinaemia by two distinct saturable processes. One process was stimulated when cells from normal subjects were preincubated with lipoprotein-free medium, was inhibited by excess unlabelled low-density lipoproteins (LDL) and was absent from cells from subjects with homozygous familial hypercholesterolaemia; on these criteria it was identified as an LDL-receptor-dependent process. Degradation by the second process was of equal magnitude in both cell types and was unaffected by excess unlabelled LDL or acetylated LDL. The activity of this process was reduced when the cells were preincubated in lipoprotein-free medium. The abnormal VLDL from the plasma of cholesterol-fed rabbits were also degraded by this process, which was similar to that in mouse peritoneal macrophages mediated by the receptor for VLDL of beta-electrophoretic mobility [Goldstein, Ho, Brown, Innerarity & Mahley (1980) J. Biol. Chem. 255, 1839-1848].

Selective uptake of cholesteryl esters from various classes of lipoproteins by HepG2 cells

1999 ◽  
Vol 77 (2) ◽  
pp. 157-163 ◽  
Author(s):  
Louise Brissette ◽  
Marie-Claude Charest ◽  
Louise Falstrault ◽  
Julie Lafond ◽  
David Rhainds ◽  
...  
Keyword(s):  
Total Lipid ◽  
Hepg2 Cells ◽  
Ldl Receptor ◽  
Inverse Correlation ◽  
Low Density Lipoproteins ◽  
High Density Lipoproteins ◽  
Low Density ◽  
Cholesteryl Esters ◽  
Very Low Density Lipoproteins ◽  
Selective Uptake

Selective uptake of cholesteryl esters (CE) from lipoproteins by cells has been extensively studied with high density lipoproteins (HDL). It is only recently that such a mechanism has been attributed to intermediate and low density lipoproteins (IDL and LDL). Here, we compare the association of proteins and CE from very low density lipoproteins (VLDL), IDL, LDL and HDL3 to HepG2 cells. These lipoproteins were either labelled in proteins with 125I or in CE with 3H-cholesteryl oleate. We show that, at any lipoprotein concentration, protein association to the cells is significantly smaller for IDL, LDL, and HDL3 than CE association, but not for VLDL. At a concentration of 20 µg lipoprotein/mL, these associations reveal CE-selective uptake in the order of 2-, 4-, and 11-fold for IDL, LDL, and HDL3, respectively. These studies reveal that LDL and HDL3 are good selective donors of CE to HepG2 cells, while IDL is a poor donor and VLDL is not a donor. A significant inverse correlation (r2 = 0.973) was found between the total lipid/protein ratios of the four classes of lipoproteins and the extent of CE-selective uptake by HepG2 cells. The fate of 3H-CE of the two best CE donors (LDL and HDL3) was followed in HepG2 cells after 3 h of incubation. Cells were shown to hydrolyze approximately 25% of the 3H-CE of both lipoproteins. However, when the cells were treated with 100 µM of chloroquine, a lysosomotropic agent, 85 and 40% of 3H-CE hydrolysis was lost for LDL and HDL3, respectively. The fate of LDL and HDL3-CE in HepG2 cells deficient in LDL-receptor was found to be the same, indicating that the portion of CE hydrolysis sensitive to chloroquine is not significantly linked to LDL-receptor activity. Thus, in HepG2 cells, the magnitude of CE-selective uptake is inversely correlated with the total lipid/protein ratios of the lipoproteins and CE-selective uptake from the two best CE donors (LDL and HDL3) appears to follow different pathways.Key words: lipoprotein, receptor, HepG2 cell, selective uptake, lipid, cholesterol, binding.

scholarly journals Effect of Exposure of Human Monocyte-Derived Macrophages to High, versus Normal, Glucose on Subsequent Lipid Accumulation from Glycated and Acetylated Low-Density Lipoproteins

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Fatemeh Moheimani ◽  
Joanne T. M. Tan ◽  
Bronwyn E. Brown ◽  
Alison K. Heather ◽  
David M. van Reyk ◽  
...  
Keyword(s):  
High Glucose ◽  
Lipid Accumulation ◽  
Scavenger Receptor ◽  
Ldl Receptor ◽  
Human Monocyte ◽  
Low Density Lipoproteins ◽  
Receptor Expression ◽  
Low Density ◽  
Cholesteryl Esters ◽  
Protein Levels

During atherosclerosis monocyte-derived macrophages accumulate cholesteryl esters from low-density lipoproteins (LDLs) via lectin-like oxidised LDL receptor-1 (LOX-1) and class AI and AII (SR-AI, SR-AII) and class B (SR-BI, CD36) scavenger receptors. Here we examined the hypothesis that hyperglycaemia may modulate receptor expression and hence lipid accumulation in macrophages. Human monocytes were matured into macrophages in 30 versus 5 mM glucose and receptor expression and lipid accumulation quantified. High glucose elevated LOX1 mRNA, but decreased SR-AI, SR-BI, LDLR, and CD36 mRNA. SR-BI and CD36 protein levels were decreased. Normo- and hyperglycaemic cells accumulated cholesteryl esters from modified LDL to a greater extent than control LDL, but total and individual cholesteryl ester accumulation was not affected by glucose levels. It is concluded that, whilst macrophage scavenger receptor mRNA and protein levels can be modulated by high glucose, these are not key factors in lipid accumulation by human macrophages under the conditions examined.

Aggregation of Human Blood Platelets by Remnant Like Lipoprotein Particles of Plasma Chylomicrons and Very Low Density Lipoproteins

1997 ◽  
Vol 77 (05) ◽  
pp. 0996-1001 ◽  
Author(s):  
Abby R Saniabadi ◽  
Kazou Umemura ◽  
Makiko Shimoyama ◽  
Masakazu Adachi ◽  
Minoru Nakano ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Blood Platelets ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Red Cell ◽  
Very Low Density Lipoproteins ◽  
Apo B ◽  
Unbound Fraction ◽  
Lipoprotein Particles ◽  
Apo E

SummaryRemnant like lipoprotein particles (RLP) of partially catabolised human plasma chylomicrons (CM) and very low density lipoproteins (VLDL) were separated from CM and VLDL using two monoclonal antibodies, anti apo B-100 (JI-H) and anti apo A-I (H-12) coupled to Sepharose 4B gel to form an immunoaffinity column. Lipoproteins containing apo B-100 or apo E, including VLDL and LDL adsorb to (JI-H)-gel, while CM and HDL with apo A-I adsorb to (H-12)-gel. The unbound fraction (RLP) is rich in apo B-48, apo E and apo E rich apo B-100 which has not been recognized by JI-H. The RLP fraction with a total triglyceride of 12.35 ± 6.22 mg/ml; total cholesterol, 0.32 ± 0.08 mg/ml and total protein, 0.72 ± 0.12 mg/ml (mean ± S.E.M, n = 9) was added to blood from healthy persons at 2.5-200 |xl/ml and agitated gently at 37° C for 40 s. Platelet aggregation was assessed by measuring the loss of single platelets. At 2.5-10 μl, RLP induced platelet aggegation increased with the dose of RLP, but decreased at 25-200 julL Scanning electron microscopy revealed that within 20 s of agitation in the presence of RLP, activated platelets had appeared on the red cell membrane and within 40 s of agitation, platelet aggregates had formed on the red cells. The platelet responses were unaffected by aspirin (10 or 20 μg/ml) but were inhibited by cilostazol, a phosphodiesterase type III inhibitor (0.4 to 1.6 μg/ml). It is likely that the platelet effect of RLP is a consequence of RLP dependent red cell-platelet interaction. This is the first report of platelet aggregation induced by RLP without an added platelet agonist.

The levels of apolipoprotein-E in hypercholesteroiemic rat serum

1978 ◽  
Vol 56 (3) ◽  
pp. 161-166 ◽  
Author(s):  
Laurence Wong ◽  
David Rubinstein
Keyword(s):  
Golgi Apparatus ◽  
Apolipoprotein E ◽  
Fold Increase ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Rat Serum ◽  
Apo E ◽  
Control Serum ◽  
Lipoprotein Complex

The levels of apolipoprotein-E (apo-E) in serum and isolated lipoproteins from diet-induced hypercholesterolemic, and to some extent, hypertriglycerdemic rats were measured by electroimmunoassay. The hypocholesterolemia was accompanied by a mild hypertriglyceridemia. The apo-E was increased by 60% in the hypercholesterolemic serum with a 5- and 50-fold increase in very low density lipoproteins (VLDL) and low density lipoproteins (LDL) respectively. However, the proportion of apo-E in nascent VLDL isolated from the hepatic Golgi apparatus of hypercholesterolemic rats was significantly decreased. In control serum, 40–50% of the apo-E is found in the density >1.21 g/ml fraction, although this is at least partially due to ultracentrifugation. The aproprotein is absent from the density >1.21 g/ml fraction from hypercholesterolemic serum, suggesting that it is bound more firmly to the lipoprotein complex. It is concluded that the large increases in apo-E in the VLDL and LDL density ranges of serum from hypercholesterolemic rats may in part be accounted for by the utilization of apo-E normally found at higher densities.

A comparison of some immunological characteristics of very low density lipoproteins of normal and hypercholesterolemic rat sera

1978 ◽  
Vol 56 (6) ◽  
pp. 673-683 ◽  
Author(s):  
Peter J. Dolphin ◽  
Laurence Wong ◽  
David Rubinstein
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
Normal Serum ◽  
Low Density Lipoproteins ◽  
High Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Rat Serum ◽  
Apo B ◽  
Apo E

The immunological characteristics of very low density lipoproteins (VLDL) from normal and hypercholesterolemic rat sera were compared using polyspecific antisera to VLDL and high density lipoproteins (HDL) and monospecific antisera to apo-B, apo-C, apo-A-I, and apo-E. Ultracentrifugally isolated VLDL from normal serum were studied by immunodiffusion and found to contain both discrete and associated (with apo-B) apo-C and apo-E, probably in the form of lipid-containing lipoproteins. However, immunoelectrophoresis of whole serum revealed only an associated form of the lipoprotein having pre-β mobility (i.e., VLDL), suggesting that the presence of discrete lipoproteins in isolated VLDL, each containing a single apoprotein family, may represent ultracentrifugal artifacts. Ultracentrifugally isolated VLDL from diet-induced hypercholesterolemic rat serum contained only trace amounts of apo-C and large quantities of apo-E, both of which were totally associated with apo-B. VLDL isolated by ultracentrifugation from perfusate of normal and hypercholesterolemic livers contained only associated lipoprotein complexes made up of apo-B, apo-C, and apo-E in the former but only apo-B and apo-E in the latter. These data suggest that normal VLDL are secreted as lipoprotein complexes containing apo-B, apo-C, and apo-E which may become destabilized in the circulation. However, VLDL from hypercholesterolemic serum show a marked diminution in the quantity of apo-C as indicated by the relative incorporation of [3H]leucine in vivo and by polyacrylamide gel electrophoresis of apo-VLDL.

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