Intracellular transport of low density lipoprotein derived free cholesterol begins at clathrin-coated pits and terminates at cell surface caveolae.
Free cholesterol (FC) is selectively internalized from low-density lipoprotein (LDL) by confluent fibroblast monolayers (Fielding & Fielding (1995) Biochemistry 34, 14237-14244). The kinetics of transport of LDL-derived 3H-FC within the cell were studied by density-gradient ultracentrifugal fractionation and in terms of the effects of inhibitors of endocytosis and intracellular transport. By these criteria, the initial uptake of LDL-FC was mediated by the cell-surface clathrin-coated pits. FC label then appeared in clathrin-coated dense vesicles. Uncoating of clathrin from these vesicles led to the appearance of label in a light density fraction and, subsequently, in an intermediate density fraction coincident with protein markers of the trans-Golgi network in these cells. 3H-FC was finally transported to the plasma membrane via a temperature-sensitive, probably microtubule-dependent pathway. These data are consistent with a role for the trans-Golgi network as an intermediate compartment in intracellular FC transport. They provide further evidence of a role for cell-surface caveolae in FC efflux.
Fielding
P E
PE
Department of Medicine, University of California, San Francisco 94143-0130, USA.
Fielding
C J
CJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D008078:Cholesterol, LDL / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism*; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism*; D015638:Cytochalasin D / Q000494:pharmacology; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism; D018942:Macrolides; D008985:Monensin / Q000494:pharmacology; D015739:Nocodazole / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism
D000900:Anti-Bacterial Agents; D008078:Cholesterol, LDL; D002966:Clathrin; D008074:Lipoproteins; D018942:Macrolides; C057620:bafilomycin A; D015638:Cytochalasin D; D008985:Monensin; D015739:Nocodazole