Cellular cholesterol efflux

CJ Fielding, PE Fielding - Biochimica et Biophysica Acta (BBA)-Molecular …, 2001 - Elsevier
CJ Fielding, PE Fielding
Biochimica et Biophysica Acta (BBA)-Molecular and Cell Biology of Lipids, 2001Elsevier
Efflux of free cholesterol (FC) continues even when cellular FC mass is unchanged. This
reflects a recirculation of preformed FC between cells and extracellular fluids which has
multiple functions in cell biology including receptor recycling and signaling as well as
cellular FC homeostasis. Total FC efflux is heterogenous. Simple diffusion to mature high
density lipoprotein (HDL), mainly via albumin as intermediate, initiates FC net transport
driven by plasma lecithin: cholesterol acyltransferase activity. A second major efflux …
Efflux of free cholesterol (FC) continues even when cellular FC mass is unchanged. This reflects a recirculation of preformed FC between cells and extracellular fluids which has multiple functions in cell biology including receptor recycling and signaling as well as cellular FC homeostasis. Total FC efflux is heterogenous. Simple diffusion to mature high density lipoprotein (HDL), mainly via albumin as intermediate, initiates FC net transport driven by plasma lecithin:cholesterol acyltransferase activity. A second major efflux component reflects protein-facilitated transport from cell surface domains (caveolae, rafts) driven by FC binding to lipid-poor, pre-β-migrating HDL (pre-β-HDL). Facilitated efflux from caveolae, unlike simple diffusion, is highly regulated. Neither ABC1 (the protein defective in Tangier disease) nor other ATP-dependent transporters now appear likely to contribute directly to FC efflux. Their role is limited to the initial formation of a particle precursor to circulating pre-β-HDL, which recycles without further lipid input from ATP-dependent transporter proteins. Lipid-free apolipoprotein A-I, previously considered a surrogate for pre-β-HDL, has a reactivity much lower than that of native lipoprotein FC acceptors.
Elsevier