Critical shape transitions of monolayer lipid domains

Rice, Peter A.; McConnell, Harden M.

doi:10.1073/pnas.86.17.6445

Cited by 72 publications

(51 citation statements)

References 9 publications

(15 reference statements)

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“…Cholesterol domains were observed in both native and reconstituted lens membranes and remained stable over a broad range of temperature and relative humidity levels (27). These findings were consistent with the idea that pure cholesterol phases form within cell membranes at C/P mole ratios in excess of 1.0 (30), as confirmed by a number of experiments employing theoretical, model, and native membrane systems (31)(32)(33)(34)(35)(36)(37).…”

supporting

confidence: 74%

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Jacob

Cenedella

Mason

2001

Journal of Biological Chemistry

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Previous studies in our laboratory have provided direct evidence for the existence of distinct cholesterol domains within the plasma membranes of human ocular lens fiber cells. The fiber cell plasma membrane is unique in that it contains unusually high concentrations of cholesterol, with cholesterol to phospholipid (C/P) mole ratios ranging from 1 to 4. Since membrane cholesterol content is disturbed in the development of cataracts, it was hypothesized that perturbation of cholesterol domain structure occurs in cataracts. In this study, fiber cell plasma membranes were isolated from both normal (control) and cataractous lenses and assayed for cholesterol and phospholipid. Control and cataractous whole lens membranes had C/P mole ratios of 3.1 and 1.7, respectively. Small angle x-ray diffraction approaches were used to directly examine the structural organization of the cataractous lens plasma membrane versus control. Both normal and cataractous oriented membranes yielded meridional diffraction peaks corresponding to a unit cell periodicity of 34.0 Å, consistent with the presence of immiscible cholesterol domains. However, comparison of diffraction patterns indicated that cataractous lens membranes contained more pronounced and better defined cholesterol domains than controls, over a broad range of temperature (5-40°C) and relative humidity (52-92%) levels. In addition, diffraction analyses of the sterol-poor regions of cataractous membranes indicated increased membrane rigidity as compared with control membranes. Modification of the membrane lipid environment, such as by oxidative insult, is believed to be one potential mechanism for the formation of highly resolved cholesterol domains despite significantly reduced cholesterol content. The results of this x-ray diffraction study provide evidence for fundamental changes in the lens fiber cell plasma membrane structure in cataracts, including the presence of more prominent and highly ordered, immiscible cholesterol domains.

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supporting

confidence: 74%

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Jacob

Cenedella

Mason

2001

Journal of Biological Chemistry

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“…Appropriate mixtures of dimyristoyl phosphatidylcholine (DMPC) and cholesterol (30)(31)(32) and DPPC-cholesterol (34,35) exhibit the same characteristics of a critical point, although at pressures well below the values at which remixing occurs here. Surfactant preparations, however, that contain the complete set of phospholipids are far from binary mixtures.…”

Section: Discussionmentioning

confidence: 99%

Neutral Lipids Induce Critical Behavior in Interfacial Monolayers of Pulmonary Surfactant

et al. 1998

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We have shown previously that lateral compression of pulmonary surfactant monolayers initially induces separation of two phases but that these remix when the films become more dense (1). In the studies reported here, we used fluorescence microscopy to examine the role of the different surfactant constituents in the remixing of the separated phases. Subfractions containing only the purified phospholipids (PPL), the surfactant proteins and phospholipids (SP&PL), and the neutral and phospholipids (N&PL) were obtained by chromatographic separation of the components in extracted calf surfactant (calf lung surfactant extract, CLSE). Compression of the different monolayers produced nonfluorescent domains that emerged for temperatures between 20 and 41°C at similar surface pressures 6-8 mN/m higher than values observed for dipalmitoyl phosphatidylcholine (DPPC), the most prevalent component of pulmonary surfactant. Comparison of the different preparations showed that the neutral lipid increased the total nonfluorescent area at surface pressures up to 25 mN/m but dispersed that total area among a larger number of smaller domains. The surfactant proteins also produced smaller domains, but they had the opposite effect of decreasing the total nonfluorescent area. Only the neutral lipids caused remixing. In images from static monolayers, the domains for N&PL dropped from a maximum of 26 ± 3% of the interface at 25 mN/m to 4 ± 2% at 30 mN/m, similar to the previously reported behavior for CLSE. During continuous compression through a narrow range of pressure and molecular area, in N&PL, CLSE, and mixtures of PPL with 10% cholesterol, domains became highly distorted immediately prior to remixing. The characteristic transition in shape and abrupt termination of phase coexistence indicate that the remixing caused by the neutral lipids occurs at or close to a critical point. † © 1999 American Chemical Society * To whom correspondence should be addressed at Mail Code OHSU, Portland,.. NIH Public Access Author ManuscriptBiochemistry. Author manuscript; available in PMC 2012 December 08. The phase behavior of biological phospholipid films and membranes may be important in at least two respects. First, the different physical characteristics of the different phases can alter processes such as lateral diffusion. Second, phase separation can maintain components in distinct compartments and provide a means of organizing biological processes (2). Both of these issues may be important for the function of pulmonary surfactant. This complex mix of lipids and proteins coats the thin liquid layer that lines the lung's alveolar air spaces. When compressed by decreasing alveolar surface areas during normal exhalation, the surfactant film achieves very high densities, well above equilibrium values. Measurements in situ show that the surfactant films lower the surface tension of the air-liquid interface to very low levels (3) and in doing so stabilize the alveoli. Only films with the physical characteristics of a highly ordered phase se...

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“…50 mole % sterol) can yield pure cholesterol phases (12). In well defined lipid monolayer systems, the addition of cholesterol produces lateral sterol domains, as characterized by microscopy approaches (13)(14)(15). The formation of distinct cholesterol domains has also been observed in various membrane bilayer systems.…”

mentioning

confidence: 92%

“…Although the mechanisms responsible for the preferential interaction of cholesterol with sphingomyelin are not fully understood, it is believed that an increased probability of van der Waal's forces may contribute to the strength of their interaction (14,30,34). It should be pointed out that sphingomyelin is not required for the formation of cholesterol domains since domains have been observed in systems composed exclusively of other lipids (28), including dimyristoylphosphatidylcholine (35), dipalmitoylphosphatidylcholine (13), N-palmitoylgalactosylsphingosine (16), and dimyristoylphosphatidylserine (28). However, recent experiments conducted in our laboratory suggest that cholesterol domains form more readily in cholesterol/sphingomyelin binary mixtures and exhibit stability characteristics similar to that of cholesterol domains formed in the lens fiber cell plasma membrane (unpublished data).…”

Section: Figmentioning

confidence: 99%

Direct Evidence for Immiscible Cholesterol Domains in Human Ocular Lens Fiber Cell Plasma Membranes

Jacob¹,

Cenedella

Mason³

1999

Journal of Biological Chemistry

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The molecular structure of human ocular lens fiber cell plasma membranes was examined directly using small angle x-ray diffraction approaches. A distinct biochemical feature of these membranes is their high relative levels of free cholesterol; the mole ratio of cholesterol to phospholipid (C/P) measured in these membranes ranges from 1 to 4. The organization of cholesterol in this membrane system is not well understood, however. In this study, the structure of plasma membrane samples isolated from nuclear (3.3 C/P) and cortical (2.4 C/P) regions of human lenses was evaluated with x-ray diffraction approaches. Meridional diffraction patterns obtained from the oriented membrane samples demonstrated the presence of an immiscible cholesterol domain with a unit cell periodicity of 34.0 Å, consistent with a cholesterol monohydrate bilayer. The dimensions of the sterol-rich domains remained constant over a broad range of temperatures (5-20°C) and relative humidity levels (31-97%). In contrast, dimensions of the surrounding sterol-poor phase were significantly affected by experimental conditions. Similar structural features were observed in membranes reconstituted from fiber cell plasma membrane lipid extracts. The results of this study indicate that the lens fiber cell plasma membrane is a complex structure consisting of separate sterol-rich and -poor domains. Maintenance of these separate domains may be required for the normal function of lens fiber cell plasma membrane and may interfere with the cataractogenic aggregation of soluble lens proteins at the membrane surface.

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Critical shape transitions of monolayer lipid domains

Abstract: Fluorescence microscopy can be used to visualize coexisting fluid phases in lipid monolayers composed of cholesterol and dipalmitoyl phosphatidyicholine under specified conditions oftemperature, composition, and lateral pressure.

Cited by 72 publications

References 9 publications

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Neutral Lipids Induce Critical Behavior in Interfacial Monolayers of Pulmonary Surfactant

Direct Evidence for Immiscible Cholesterol Domains in Human Ocular Lens Fiber Cell Plasma Membranes

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