scholarly journals Apolipoprotein (apo) E genotype and apoE concentration determine binding of normal very low density lipoproteins to HepG2 cell surface receptors.

1996 ◽  
Vol 37 (6) ◽  
pp. 1316-1324
Author(s):  
K Bohnet ◽  
T Pillot ◽  
S Visvikis ◽  
N Sabolovic ◽  
G Siest
Keyword(s):  
Cell Surface ◽  
Hepg2 Cell ◽  
Low Density Lipoproteins ◽  
Cell Surface Receptors ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Surface Receptors ◽  
Apo E ◽  
Apo E Genotype

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.

The catabolism of very low density lipoproteins

1985 ◽  
Vol 63 (8) ◽  
pp. 890-897 ◽  
Author(s):  
W. Carl Breckenridge
Keyword(s):  
Surface Composition ◽  
Hepatic Lipase ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Core Particle ◽  
Mechanism Of Formation ◽  
Very Low Density Lipoproteins ◽  
Apo E

The lipolysis of very low density lipoproteins (VLDL) in vitro is a useful model for the study of the process of conversion of this triacylglycerol rich lipoprotein into low (LDL) and high (HDL) density lipoproteins. Data is reviewed to show that a portion of surface cholesterol and phospholipid which becomes redundant during lipolysis is lost from the lipoprotein. In the absence of HDL, the material forms lipoprotein-X (LpX) like vesicles which are not readily disrupted by HDL once they are formed. In the presence of HDL during lipolysis, the material is largely incorporated into HDL. The data is used to suggest a mechanism of formation of LpX-like vesicles in conditions where the production of surface remnants exceeds the capacity of HDL to disrupt them. Evidence is also provided to show that apolipoproteins (apo) C-II, C-III, and E are lost from VLDL and that this loss is primarily in association with a neutral core particle of HDL size which can subsequently exchange lipids and apolipoproteins with plasma HDL. Such a mechanism could account for the removal of apo E and excess cholesteryl ester which is necessary for conversion of VLDL to LDL. The role of hepatic lipase in this process remains speculative. Recent evidence is reviewed and used to propose that the enzyme may serve to rearrange the neutral core and surface composition of LDL and HDL subfractions to allow for the packaging of cholesteryl esters and the cycling of apolipoproteins.

The Influence of Apolipoprotein E on the Interactions between Normal Human Very Low Density Lipoproteins and U937 Human Macrophages: Heterogeneity among Persons

1996 ◽  
Vol 1 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Frank M Sacks ◽  
Gregory P Krukonis
Keyword(s):  
Apolipoprotein E ◽  
Binding Activity ◽  
Low Density Lipoproteins ◽  
Similar Proportion ◽  
Low Density ◽  
U937 Cells ◽  
Cell Binding ◽  
Very Low Density Lipoproteins ◽  
Apo E ◽  
Normal Human

Apolipoprotein E (apo E) can mediate the cell binding of normal human very low density lipoproteins (VLDL). However, the extent to which apo E is involved in the cell binding and uptake of VLDL from different normolipidemic persons is not well defined. The VLDL ( d< 1.006 g/I) of eight subjects were fractionated into VLDL with apo E and without apo E using a monoclonal antibody that binds to the LDL receptor recognition region of apo E. VLDL particles that expressed the 1D7 binding region of apo E comprised an average of 34% (range 7–51%) of the VLDL particles. Anti-apo E blocked an average of 43% (range 8–63%) of the binding of unfractionated VLDL to U937 cells. Anti-apo E blocked a similar proportion of binding to U937 cells of three VLDL subfractions of different density ranges (Sf20–60, Sf60–100, Sf100–400). The proportion of the VLDL particles that contained apo E correlated with the extent of uptake of the total VLDL by U937 cells, but not with stimulation by total VLDL of cholesterol ester formation. The binding to cells of VLDL without apo E varied by six-fold among persons, and caused most of the binding of the total VLDL of some subjects. Therefore, normolipidemic VLDL contains particles across its density range that use apo E to bind to U937 macrophages. In some VLDL samples, apo E provides most of the cell binding activity, whereas in others the binding activity occurs by other means.

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