scholarly journals Direct observation of lipoprotein cholesterol ester degradation in lysosomes

1998 ◽  
Vol 332 (2) ◽  
pp. 451-457 ◽  
Author(s):  
Sari LUSA ◽  
Kimmo TANHUANPÄÄ ◽  
Titta EZRA ◽  
Pentti SOMERHARJU
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Living Cells ◽  
Cholesterol Esters ◽  
Lysosomal Degradation ◽  
Phospholipid Micelles ◽  
Imaging Results ◽  
Arterial Intima ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

We have investigated whether pyrene-labelled cholesterol esters (PyrnCEs) (n indicates the number of aliphatic carbons in the pyrene-chain) can be used to observe the degradation of low-density lipoprotein (LDL)-derived cholesterol esters (CEs) in the lysosomes of living cells. To select the optimal substrates, hydrolysis of the PyrnCE species by lysosomal acid lipase (LAL) in detergent/phospholipid micelles was compared. The rate of hydrolysis varied markedly depending on the length of the pyrenyl chain. Pyr10CE was clearly the best substrate, while Pyr4CE was practically unhydrolysed. Pyr10CE and [3H]cholesteryl linoleate, the major CE species in LDL, were hydrolysed equally by LAL when incorporated together into reconstituted LDL (rLDL) particles, thus indicating that Pyr10CE is a reliable reporter of the lysosomal degradation of native CEs. When rLDL particles containing Pyr4CE or Pyr10CE were incubated with fibroblasts, the accumulation of bright intracellular vesicular fluorescence was observed with the former fluorescent derivative, but not with the latter. However, when the cells were treated with chloroquine, an inhibitor of lysosomal hydrolysis, or when cells with defective LAL were employed, Pyr10CE also accumulated in vesicular structures. HPLC analysis of cellular lipid extracts fully supported these imaging results. It is concluded that PyrnCEs can be used to observe degradation of CEs directly in living cells. This should be particularly useful when exploring the mechanisms responsible for the accumulation of lipoprotein-derived CEs in complex systems such as the arterial intima.

Intralysosomal Accumulation of Colloidal Gold-Low Density Lipoprotein Conjugates in Chloroquine-Treated Fibroblasts

1985 ◽  
Vol 43 ◽  
pp. 546-547 ◽  
Author(s):  
Dean A. Handley ◽  
Cynthia M. Arbeeny ◽  
Larry D. Witte
Keyword(s):  
Colloidal Gold ◽  
Cultured Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Coated Vesicle ◽  
Low Density ◽  
Cholesterol Esters ◽  
Cultured Fibroblasts ◽  
Surface Receptors ◽  
Ldl Particles

Low density lipoproteins (LDL) are the major cholesterol carrying particles in the blood. Using cultured cells, it has been shown that LDL particles interact with specific surface receptors and are internalized via a coated pit-coated vesicle pathway for lysosomal catabolism. This (Pathway has been visualized using LDL labeled to ferritin or colloidal gold. It is now recognized that certain lysomotropic agents, such as chloroquine, inhibit lysosomal enzymes that degrade protein and cholesterol esters. By interrupting cholesterol ester hydrolysis, chloroquine treatment results in lysosomal accumulation of cholesterol esters from internalized LDL. Using LDL conjugated to colloidal gold, we have examined the ultrastructural effects of chloroquine on lipoprotein uptake by normal cultured fibroblasts.

scholarly journals Hydrolysis of cholesteryl ester in low density lipoprotein converts this lipoprotein to a liposome.

1992 ◽  
Vol 267 (7) ◽  
pp. 4992-4998
Author(s):  
F.F. Chao ◽  
E.J. Blanchette-Mackie ◽  
V.V. Tertov ◽  
S.I. Skarlatos ◽  
Y.J. Chen ◽  
...  
Keyword(s):  
Cholesteryl Ester ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Hydrolysis Of

scholarly journals Aggregation Susceptibility of Low-Density Lipoproteins—A Novel Modifiable Biomarker of Cardiovascular Risk

2021 ◽  
Vol 10 (8) ◽  
pp. 1769
Author(s):  
Katariina Öörni ◽  
Petri T. Kovanen
Keyword(s):  
Ex Vivo ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Atherosclerotic Cardiovascular Disease ◽  
Low Density ◽  
Cholesterol Crystals ◽  
Ldl Particles ◽  
Arterial Intima ◽  
Matrix Bound ◽  
Atherosclerotic Cardiovascular Diseases

Circulating low-density lipoprotein (LDL) particles enter the arterial intima where they bind to the extracellular matrix and become modified by lipases, proteases, and oxidizing enzymes and agents. The modified LDL particles aggregate and fuse into larger matrix-bound lipid droplets and, upon generation of unesterified cholesterol, cholesterol crystals are also formed. Uptake of the aggregated/fused particles and cholesterol crystals by macrophages and smooth muscle cells induces their inflammatory activation and conversion into foam cells. In this review, we summarize the causes and consequences of LDL aggregation and describe the development and applications of an assay capable of determining the susceptibility of isolated LDL particles to aggregate when exposed to human recombinant sphingomyelinase enzyme ex vivo. Significant person-to-person differences in the aggregation susceptibility of LDL particles were observed, and such individual differences largely depended on particle lipid composition. The presence of aggregation-prone LDL in the circulation predicted future cardiovascular events in patients with atherosclerotic cardiovascular disease. We also discuss means capable of reducing LDL particles’ aggregation susceptibility that could potentially inhibit LDL aggregation in the arterial wall. Whether reductions in LDL aggregation susceptibility are associated with attenuated atherogenesis and a reduced risk of atherosclerotic cardiovascular diseases remains to be studied.

scholarly journals Oxidized-low density lipoprotein accumulates cholesterol esters via the PKCα-adipophilin-ACAT1 pathway in RAW264.7 cells

2015 ◽  
Vol 12 (3) ◽  
pp. 3599-3606 ◽  
Author(s):  
YUNCHENG QIAO ◽  
DONGMING GUO ◽  
LEI MENG ◽  
QINGNAN LIU ◽  
XIAOHUI LIU ◽  
...  
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Raw264.7 Cells ◽  
Low Density ◽  
Cholesterol Esters ◽  
Oxidized Low Density Lipoprotein

Nascent and remnant lipoprotein turnover in rats: experimental design and simulation

1983 ◽  
Vol 245 (3) ◽  
pp. R386-R395
Author(s):  
N. Baker ◽  
H. J. Rostami ◽  
J. Elovson
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Simulation Analysis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Kinetic Behavior ◽  
Turnover Rates ◽  
Apoprotein B ◽  
Hydrolysis Of

We have attempted to predict the kinetic behavior of the complex very low-density lipoprotein (VLDL; d less than 1.006) fraction in blood plasma of rats in the steady state. Specifically we proposed a simple model with two different kinds of nascent VLDL particles derived from the liver, one containing apoprotein B (PI/II) [apoB(PI/II)], the high-molecular-weight apoB, and the other, apoprotein B (PIII) [apoB(PIII)], the low-molecular-weight apoB. Two other particles, the corresponding remnants derived from the nascent VLDL particles were also included. Then a number of feasible in vivo tracer experiments were considered in which VLDL labeled in the apoB and/or triglyceride (TG) moieties would be injected into recipient rats and the kinetic behavior of the various compartments predicted by simulation analysis. In addition the kinetic behavior of products such as free fatty acids formed during hydrolysis of labeled TG fatty acids and liver TG derived from labeled circulating remnants was considered. Both the relative sizes of nascent and remnant particles and the extent of average hydrolysis of nascent VLDL-TG (before formation of a remnant particle) were considered in our analysis. On the basis of these predictions we have suggested a number of experimental approaches that should be helpful in defining the relative pool sizes and the turnover rates of each kind of particle in vivo.

scholarly journals Binding, internalization, and hydrolysis of low density lipoprotein in long-term lymphoid cell lines from a normal subject and a patient with homozygous familial hypercholesterolemia.

1976 ◽  
Vol 144 (2) ◽  
pp. 444-455 ◽  
Author(s):  
Y K Ho ◽  
M S Brown ◽  
H J Kayden ◽  
J L Goldstein
Keyword(s):  
Cell Surface ◽  
Familial Hypercholesterolemia ◽  
Human Lymphocytes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lymphoid Cells ◽  
Low Density ◽  
High Affinity ◽  
Hydrolysis Of

Long-term established human lymphoid cells were shown to possess high affinity cell surface receptors for low density lipoprotein (LDL), the major cholesterol-carrying protein in human plasma. Binding of LDL to these receptors was followed by internalization of the lipoprotein and hydrolysis of its protein and cholesteryl ester components. Cultured lymphocytes from a patient with the homozygous form of familial hypercholesterolemia lacked cell surface LDL receptors and therefore failed to take up and degrade the lipoprotein with high affinity. Cultured human lymphocytes should prove useful for further studies of: (a) the relation between cholesterol metabolism and cellular function and (b) the mechanism by which LDL binding at the cell surface leads to internalization of the lipoprotein.

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