title: Adhesion stabilizes robust lipid heterogeneity in supercritical membranes at physiological temperature.
abstract: Regions of contact between cells are frequently enriched in or depleted of certain protein or lipid species. Here, we explore a possible physical basis that could contribute to this membrane heterogeneity using a model system of a giant vesicle tethered to a planar supported bilayer. Vesicles contain coexisting liquid-ordered (L(o)) and liquid-disordered (L(d)) phases at low temperatures and are tethered using trace quantities of adhesion molecules that preferentially partition into one liquid phase. We find that the L(d) marker DiI-C(12) is enriched or depleted in the adhered region when adhesion molecules partition into L(d) or L(o) phases, respectively. Remarkably, adhesion stabilizes an extended zone enriched or depleted of DiI-C(12) even at temperatures >15°C above the miscibility phase transition when membranes have compositions that are in close proximity to a critical point. A stable adhesion zone is also observed in plasma membrane vesicles isolated from living RBL-2H3 cells, and probe partitioning at 37°C is diminished in vesicles isolated from cells with altered cholesterol levels. Probe partitioning is in good quantitative agreement with predictions of the two-dimensional Ising model with a weak applied field for both types of model membranes. These studies experimentally demonstrate that large and stable domain structure can be mediated by lipids in single-phase membranes with supercritical fluctuations.
authors: Department of Biophysics, University of Michigan, Ann Arbor, MI, USA.
authors: Jiang
authors: J
authors: Zhao
authors: Jing
authors: J
authors: Wu
authors: Sarah L
authors: SL
authors: Veatch
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002784:Cholesterol / Q000737:chemistry*; D003080:Cold Temperature; D007425:Intracellular Membranes / Q000737:chemistry / Q000502:physiology; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D044367:Phase Transition; D051381:Rats
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D002784:Cholesterol