scholarly journals Inhibition of proteolytic degradation of low density lipoprotein in human fibroblasts by chloroquine, concanavalin A, and Triton WR 1339.

1975 ◽  
Vol 250 (19) ◽  
pp. 7854-7862 ◽  
Author(s):  
JL Goldstein ◽  
GY Brunschede ◽  
MS Brown
Keyword(s):  
Concanavalin A ◽  
Low Density Lipoprotein ◽  
Human Fibroblasts ◽  
Density Lipoprotein ◽  
Proteolytic Degradation ◽  
Low Density ◽  
Triton Wr 1339

scholarly journals Effect of cell density on binding and uptake of low density lipoprotein by human fibroblasts.

1979 ◽  
Vol 83 (3) ◽  
pp. 588-594 ◽  
Author(s):  
H S Kruth ◽  
J Avigan ◽  
W Gamble ◽  
M Vaughan
Keyword(s):  
Cell Density ◽  
Low Density Lipoprotein ◽  
Human Fibroblasts ◽  
Density Lipoprotein ◽  
Low Density ◽  
Cellular Lipid ◽  
Cholesterol Accumulation ◽  
Ldl Receptors ◽  
Ldl Binding ◽  
In Cells

The effect of cell density on low density lipoprotein (LDL) binding by cultured human skin fibroblasts was investigated. Bound LDL was visualized by indirect immunofluorescence. Cellular lipid and cholesterol were monitored by fluorescence in cells stained with phosphine 3R and filipin, respectively. LDL binding and lipid accumulation were compared in cells in stationary and exponentially growing cultures, in sparsely and densely plated cultures, in wounded and non-wounded areas of stationary cultures, and in stationary cultures with and without the addition of lipoprotein-deficient serum. We conclude that LDL binding and cholesterol accumulation induced by LDL are influenced by cell density. It appears that, compared to rapidly growing cells, quiescent (noncycling) human fibroblasts exhibit fewer functional LDL receptors.

scholarly journals Physicochemical transfer of [3H]cholesterol from plasma lipoproteins to cultured human fibroblasts

1985 ◽  
Vol 228 (1) ◽  
pp. 219-225 ◽  
Author(s):  
B B Lundberg ◽  
L A Suominen
Keyword(s):  
Free Cholesterol ◽  
Water Solubility ◽  
Low Density Lipoprotein ◽  
Human Fibroblasts ◽  
Density Lipoprotein ◽  
Plasma Lipoproteins ◽  
Lung Fibroblasts ◽  
Cell Protein ◽  
Low Density ◽  
Free System

The transfer of free cholesterol from [3H]cholesterol-labelled plasma lipoproteins to cultured human lung fibroblasts was studied in a serum-free medium. The uptake of [3H]cholesterol depended upon time of incubation, concentration of lipoprotein in the medium, and temperature. Modified (reduced and methylated) low-density lipoprotein (LDL), which did not enter the cells by the receptor pathway, gave a somewhat lower transfer rate than unmodified LDL, but if the transfer values for native LDL were corrected for the receptor-mediated uptake of cholesterol the difference was eliminated. The initial rates of transfer of [3H]cholesterol from LDL and high-density lipoprotein (HDL) were of the same order of magnitude (0.67 +/- 0.05 and 0.75 +/- 0.06 nmol of cholesterol/h per mg of cell protein, respectively) while that from very-low-density lipoprotein (VLDL) was much lower (0.23 +/- 0.02 nmol of cholesterol/h per mg) (means +/- S.D., n = 5). The activation energy for transfer of cholesterol from reduced, methylated LDL to fibroblasts was determined to be 57.5 kJ/mol. If albumin was added to the incubation medium the transfer of [3H]cholesterol was enhanced, while that of [14C]dipalmitoyl phosphatidylcholine was decreased compared with the protein-free system. The results demonstrate that, in spite of its low water solubility, free cholesterol can move from lipoproteins to cellular membranes, probably by aqueous diffusion. We propose that physicochemical transfer of free cholesterol may be a significant mechanism for net uptake of the sterol into the artery during atherogenesis.

Processing and characterization of the low density lipoprotein receptor in the human colonic carcinoma cell subclone HT29-18: A potential pathway for delivering therapeutic drugs and genes

1992 ◽  
Vol 12 (6) ◽  
pp. 483-494 ◽  
Author(s):  
J. C. Mazière ◽  
C. Mazière ◽  
S. Emami ◽  
B. Noel ◽  
Y. Poumay ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Carcinoma Cell ◽  
Low Density Lipoprotein ◽  
Human Fibroblasts ◽  
Density Lipoprotein ◽  
Apparent Molecular Weight ◽  
Colonic Carcinoma ◽  
Sterol Synthesis ◽  
Low Density ◽  
Ldl Binding

Low density lipoprotein (LDL) processing has been investigated in the subcloned human colonic carcinoma cell line HT29-18. LDL binding at 4°C was a saturable process in relation to time and LDL concentration. The Kd for LDL binding was 11 μg/ml. ApoE-free HDL3 or acetylated LDL did not significantly compete with125I-LDL binding, up to 500 μg/ml.125I-LDL binding was decreased by 70% in HT29-18 cells preincubated for 24 hours in culture medium containing 100 μg/ml unlabelled LDL. Ligand blotting studies performed on HT29-18 homogenates using colloidal gold labelled LDL indicated the presence of one autoradiographic band corresponding to an apparent molecular weight of 130 kDa, which is consistent with the previously reported molecular weight of the LDL receptor in human fibroblasts. At 37°C,125I-LDL was actively internalized by HT29-18 cells and lysosomal degradation occurred as demonstrated by the inhibitory effect of chloroquine. LDL uptake and degradation by HT29-18 cells also resulted in a marked decrease in endogenous sterol synthesis. These data demonstrate that the HT29-18 human cancerous intestinal cells are able to specifically bind and internalize LDL, and that LDL processing results in down-regulation of sterol biosynthesis. Thus, intestinal epithelial cells possess specific LDL receptors that can be exploited to accomplish drug delivery and gene transfer via the receptor-mediated endocytosis pathway.

Proteolytic degradation of low-density lipoprotein by lipoprotein(a) and by recombinant apo(a)

1994 ◽  
Vol 67-68 ◽  
pp. 25-33 ◽  
Author(s):  
Mari Pursiainen ◽  
Matti Jauhiainen ◽  
Petri T. Kovanen ◽  
Christian Ehnholm
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Proteolytic Degradation ◽  
Low Density ◽  
Lipoprotein A
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