Role of estrogen in the regulation of cholesteryl ester synthesis in macrophages: the interaction between native and modified low density lipoprotein and human monocyte-derived macrophages

2002 ◽  
Vol 35 (8) ◽  
pp. 597-605 ◽  
Author(s):  
Mariarosaria Napolitano ◽  
Annarica Calcabrini ◽  
Kathleen M Botham ◽  
Elena Bravo
Keyword(s):  
Cholesteryl Ester ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Low Density ◽  
Ester Synthesis

scholarly journals Human monocyte-derived macrophages bind low-density-lipoprotein-proteoglycan complexes by a receptor different from the low-density-lipoprotein receptor

1993 ◽  
Vol 289 (3) ◽  
pp. 837-844 ◽  
Author(s):  
P Vijayagopal ◽  
S R Srinivasan ◽  
B Radhakrishnamurthy ◽  
G S Berenson
Keyword(s):  
Cholesteryl Ester ◽  
Proteolytic Enzymes ◽  
Chondroitin Sulphate ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Human Aorta ◽  
Minor Role ◽  
Low Density ◽  
Ester Synthesis

We have shown recently that lipoprotein-proteoglycan complexes isolated from human atherosclerotic lesions stimulated cholesteryl ester synthesis in human monocyte-derived macrophages [Vijayagopal, Srinivasan, Radhakrishnamurthy and Berenson (1992) Arterioscler. Thromb. 12, 237-249]. The present study was conducted to determine the mechanism of cellular uptake of the complexes. A chondroitin sulphate-dermatan sulphate proteoglycan was isolated from normal human aorta and complexed to 125I-labelled human low-density lipoprotein (LDL). The binding and degradation of 125I-LDL-proteoglycan complex were then studied in human monocyte-derived macrophages. The specific binding and degradation of the complex showed saturability and concentration-dependency. The Kd for binding was 1.5 x 10(-8) M, which was greater than that reported for LDL in monocyte-derived macrophages. Binding of the complex was not subject to down-regulation. Chloroquine inhibited degradation of the complex and the resultant stimulation of cholesteryl ester synthesis. Limited treatment of macrophages with proteolytic enzymes abolished binding and degradation of the complex significantly. Macrophages bound 125I-methyl-LDL-proteoglycan complex to the same extent as 125I-LDL-proteoglycan complex. Excess LDL and proteoglycan did not compete against the binding of the complex; however, excess acetyl-LDL competed for 61% of the binding. Likewise, excess LDL-proteoglycan complex inhibited the binding of 125I-acetyl-LDL by 64%. Polyinosinic acid and cytochalasin D inhibited the binding of 125I-LDL-proteoglycan complex by 60% and 36% respectively. Compared with that of acetyl-LDL, the degradation of LDL-proteoglycan complex was retarded in human macrophages. The results indicate that the uptake of LDL-proteoglycan complex in human monocyte-derived macrophages is not mediated through binding to the LDL receptor; but occurs predominantly via the scavenger receptor, with phagocytosis playing a minor role in the process.

Glycosylation of Low-Density Lipoprotein Enhances Cholesteryl Ester Synthesis in Human Monocyte-Derived Macrophages

Diabetes ◽  
1988 ◽  
Vol 37 (5) ◽  
pp. 550-557 ◽  
Author(s):  
M. F. Lopes-Virella ◽  
R. L. Klein ◽  
T. J. Lyons ◽  
H. C. Stevenson ◽  
J. L. Witztum
Keyword(s):  
Cholesteryl Ester ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Low Density ◽  
Ester Synthesis

Glycosylation of low-density lipoprotein enhances cholesteryl ester synthesis in human monocyte-derived macrophages

Diabetes ◽  
1988 ◽  
Vol 37 (5) ◽  
pp. 550-557 ◽  
Author(s):  
M. F. Lopes-Virella ◽  
R. L. Klein ◽  
T. J. Lyons ◽  
H. C. Stevenson ◽  
J. L. Witztum
Keyword(s):  
Cholesteryl Ester ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Low Density ◽  
Ester Synthesis

scholarly journals Receptor activities for low-density lipoprotein and acetylated low-density lipoprotein in a mouse macrophage cell line (IC21) and in human monocyte-derived macrophages.

1981 ◽  
Vol 154 (6) ◽  
pp. 1852-1867 ◽  
Author(s):  
M G Traber ◽  
V Defendi ◽  
H J Kayden
Keyword(s):  
Cholesteryl Ester ◽  
Cholesterol Synthesis ◽  
Low Density Lipoprotein ◽  
Primary Cultures ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Simian Virus 40 ◽  
Human Monocyte ◽  
Peritoneal Macrophages ◽  
Low Density

IC21 macrophages, a permanent culture of a line of cells derived from a single colony of mouse peritoneal macrophages transformed with simian virus 40, demonstrate most of the characteristics of lipoprotein metabolism that have been described for primary cultures of rodent or canine peritoneal macrophages. IC21 macrophages have low but demonstrable low-density lipoprotein (LDL) receptor activity. They actively degrade acetylated LDL (AcLDL), which has a negative charge and is not recognized by the LDL receptor. Incubation of IC21 macrophages with human lipoprotein-depleted serum leads to a marked increase in cholesterol synthesis, as measured by incorporation of labeled acetate into sterols. Sterol synthesis is inhibited by further incubation with AcLDL; incubation with LDL also decreases cholesterol synthesis with an accumulation of radioactivity from acetate in sterol intermediates, which indicates that some uptake of LDL occurs. Incubation with AcLDL but not LDL leads to a marked stimulation of cholesterol esterification, as measured by labeled oleic acid incorporation into cholesteryl esters, and a concomitant increase in cellular cholesteryl ester content. IC21 macrophages as compared with human monocyte-derived macrophages are shown to have marked difference in their abilities to degrade native LDL and AcLDL. Human monocyte-derived macrophages degrade LDL at low concentrations at a rate sevenfold greater than do IC21 macrophages. The rate of cholesteryl ester synthesis after LDL receptor induction and incubation with LDL increases linearly with LDL concentration in HMD macrophages, but no increase was found in similarly incubated IC21 macrophages. IC21 macrophages degrade AcLDL at a rate two- to fourfold greater than do human monocyte-derived macrophages.

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