Biomaterial Database

Physicochemical transfer of [3H]cholesterol from plasma lipoproteins to cultured human fibroblasts. 1985

B B Lundberg, and L A Suominen

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.

UI	MeSH Term	Description	Entries
D008074	Lipoproteins	Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.	Circulating Lipoproteins,Lipoprotein,Lipoproteins, Circulating
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D002784	Cholesterol	The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.	Epicholesterol
D005347	Fibroblasts	Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.	Fibroblast
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012710	Serum Albumin, Bovine	Serum albumin from cows, commonly used in in vitro biological studies. (From Stedman, 25th ed)	Fetal Bovine Serum,Fetal Calf Serum,Albumin Bovine,Bovine Albumin,Bovine Serum Albumin,Albumin, Bovine,Albumin, Bovine Serum,Bovine Serum, Fetal,Bovine, Albumin,Calf Serum, Fetal,Serum, Fetal Bovine,Serum, Fetal Calf
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D018110	Receptors, Lipoprotein	Cell surface proteins that bind lipoproteins with high affinity. Lipoprotein receptors in the liver and peripheral tissues mediate the regulation of plasma and cellular cholesterol metabolism and concentration. The receptors generally recognize the apolipoproteins of the lipoprotein complex, and binding is often a trigger for endocytosis.	Lipoprotein Receptors,Lipoprotein Receptor,Receptors, Lipoproteins,Lipoproteins Receptors,Receptor, Lipoprotein