Methyl-β-Cyclodextrins Preferentially Remove Cholesterol from the Liquid Disordered Phase in Giant Unilamellar Vesicles

Abstract

Methyl-β-cyclodextrins (MβCDs) are molecules that are extensively used to remove and to load cholesterol (Chol) from artificial and natural membranes; however, the mechanism of Chol extraction by MβCD from pure lipids or from complex mixtures is not fully understood. One of the outstanding questions in this field is the capability of MβCD to remove Chol from lipid domains having different packing. Here, we investigated the specificity of MβCD to remove Chol from coexisting macrodomains with different lipid packing. We used giant unilamellar vesicles (GUVs) made of 1,2-dioleoylphosphatidylcholine:1,2-dipalmitoylphatidylcholine:free cholesterol, 1:1:1 molar ratio at 27°C. Under these conditions, individual GUVs present Chol distributed into lo and ld phases. The two phases can be distinguished and visualized using Laurdan generalized polarization and two-photon excitation fluorescence microscopy. Our data indicate that MβCD removes Chol preferentially from the more disordered phase. The process of selective Chol removal is dependent on the MβCD concentration. At high concentrations, MβCD also removes phospholipids.

The mystery of membrane organization: composition, regulation and roles of lipid rafts

“…For example, it increases membrane permeability to ions and thereby disrupts membrane potential 102 , and potentially is cytotoxic 103 . Moreover, this reagent appears to preferentially remove cholesterol from liquid-disordered (non-raft) domains in model membranes 104 , which can induce unexpected and inconsistent 21,67 effects on lipid packing in more complex membranes. Drugs targeting cholesterol synthesis (statins 105 and zaragozic acid 106 ) or cholesterol-modifying enzymes (e.g.…”

Imaging lipid lateral organization in membranes with C-laurdan in a confocal microscope

“…Cyclodextrins are extensively used to remove cholesterol from artifi cial and natural membranes (see Ref. 42 ), and their effects on membrane properties have been explored using laurdan GP analysis. It has been shown that MbCD increases the fl uidity of biological membranes as assessed by a signifi cant reduction of laurdan GP ( 43 ).…”

Cholesterol Depletion from a Ceramide/Cholesterol Mixed Monolayer: A Brewster Angle Microscope Study

“…It is known that for a phospholipid/Chol mixed membrane, cholesterol is preferentially removed by MβCD from a liquid disordered (L d )-phase749. In an L o phase, because of the close proximity of the phospholipids to the cholesterol molecules, the MβCD will have difficulty to reach the cholesterol molecules.…”