title: The effect of cellular cholesterol on membrane-cytoskeleton adhesion.
abstract: Whereas recent studies suggest that cholesterol plays important role in the regulation of membrane proteins, its effect on the interaction of the cell membrane with the underlying cytoskeleton is not well understood. Here, we investigated this by measuring the forces needed to extract nanotubes (tethers) from the plasma membrane, using atomic force microscopy. The magnitude of these forces provided a direct measure of cell stiffness, cell membrane effective surface viscosity and association with the underlying cytoskeleton. Furthermore, we measured the lateral diffusion constant of a lipid analog DiIC12, using fluorescence recovery after photobleaching, which offers additional information on the organization of the membrane. We found that cholesterol depletion significantly increased the adhesion energy between the membrane and the cytoskeleton and decreased the membrane diffusion constant. An increase in cellular cholesterol to a level higher than that in control cells led to a decrease in the adhesion energy and the membrane surface viscosity. Disassembly of the actin network abrogated all the observed effects, suggesting that cholesterol affects the mechanical properties of a cell through the underlying cytoskeleton. The results of these quantitative studies may help to better understand the biomechanical processes accompanying the development of atherosclerosis.
authors.affiliation: Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO 65211, USA.
authors.forename: Mingzhai
authors.initials: M
authors.lastname: Sun
authors.forename: Nathan
authors.initials: N
authors.lastname: Northup
authors.forename: Francoise
authors.initials: F
authors.lastname: Marga
authors.forename: Tamas
authors.initials: T
authors.lastname: Huber
authors.forename: Fitzroy J
authors.initials: FJ
authors.lastname: Byfield
authors.forename: Irena
authors.initials: I
authors.lastname: Levitan
authors.forename: Gabor
authors.initials: G
authors.lastname: Forgacs
mesh_terms: D000818:Animals; D050197:Atherosclerosis; D001696:Biomechanical Phenomena; D002232:Carbocyanines / Q000737:chemistry; D002417:Cattle; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D003599:Cytoskeleton / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D042783:Endothelial Cells / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D043942:Nanotubes / Q000737:chemistry; D038761:Photobleaching
chemical_list: D002232:Carbocyanines; C097511:didodecylindocarbocyanine; D002784:Cholesterol