Intracellular transport and esterification of exchangeable cholesterol in cultured human lung fibroblasts.
We have studied the intracellular fate of exchangeable cholesterol in a model system with lipid vesicles (cholesterol/phospholipid mole ratio 1:1) and cultured human lung fibroblasts. Exchangeable [3H]cholesterol in lipid vesicles was readily incorporated into cellular plasma membranes and transported to intracellular esterification sites. The formation of [3H]cholesteryl esters was not affected by cytoskeleton-disrupting drugs. A reduction of cellular pinocytosis by 75% did not reduce the formation of tracer-labelled esters, suggesting that membrane flow due to the energy-dependent pinocytosis is no major contributor to the intracellular transport of molecular cholesterol between plasma membranes and esterification sites. The formation of [3H]cholesteryl esters was not significantly affected by energy poisons (NaF and KCN) but was inhibited (to 50%) by chloroquine at 50 microM. This may indicate that membrane-derived cholesterol passes through the lysosomal compartment on its way to intracellular esterification sites.
D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D002788:Cholesterol Esters / Q000378:metabolism*; D003078:Colchicine / Q000494:pharmacology; D003486:Cyanides / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D005459:Fluorides / Q000494:pharmacology; D006801:Humans; D008168:Lung / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D010873:Pinocytosis / Q000187:drug effects
D002788:Cholesterol Esters; D003486:Cyanides; D010743:Phospholipids; D003571:Cytochalasin B; D002784:Cholesterol; D005459:Fluorides; D003078:Colchicine