Interactions of cholesterol with the membrane lipid matrix. A solid state NMR approach

Léonard, A.; Dufourc, Érick J.

doi:10.1016/0300-9084(91)90092-f

Cited by 55 publications

(48 citation statements)

References 68 publications

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“…This decrease in acyl chain packing is associated with a reciprocal increase in molecular packing at the surface of the membrane. A reciprocal relationship between core and surface molecular packing density of the membrane has been established by others as a typical feature in a variety of membranes (39,40). These data using two separate, different, and independent methods to assess molecular packing in the membrane (i.e., fluidity and X-ray diffraction) clearly demonstrate that the apparently minor differences between cholesterol and 7-DHC structure confer significant differences in membrane lipid organization and dynamics.…”

Section: Discussionmentioning

confidence: 62%

A membrane defect in the pathogenesis of the Smith-Lemli-Opitz syndrome

Tulenko

Boeze-Battaglia

Mason

et al. 2006

Journal of Lipid Research

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The Smith-Lemli-Opitz syndrome (SLOS) is an often lethal birth defect resulting from mutations in the gene responsible for the synthesis of the enzyme 3b-hydroxy-steroid-D 7 -reductase, which catalyzes the reduction of the double bond at carbon 7 on 7-dehydrocholesterol (7-DHC) to form unesterified cholesterol. We hypothesize that the deficiency in cholesterol biosynthesis and subsequent accumulation of 7-DHC in the cell membrane leads to defective composition, organization, dynamics, and function of the cell membrane. Using skin fibroblasts obtained from SLOS patients, we demonstrate that the SLOS membrane has increased 7-DHC and reduced cholesterol content and abnormal membrane fluidity. X-ray diffraction analyses of synthetic membranes prepared to mimic SLOS membranes revealed atypical membrane organization. In addition, calcium permeability is markedly augmented, whereas membrane-bound Na + /K + ATPase activity, folate uptake, inositol-1,4,5-trisphosphate signaling, and cell proliferation rates are markedly suppressed.These data indicate that the disturbance in membrane sterol content in SLOS, likely at the level of membrane caveolae, directly contributes to the widespread tissue abnormalities in this disease.-Tulenko,

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Section: Discussionmentioning

confidence: 62%

A membrane defect in the pathogenesis of the Smith-Lemli-Opitz syndrome

Tulenko

Boeze-Battaglia

Mason

et al. 2006

Journal of Lipid Research

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“…Cholesterol is known to straighten the acyl chains of surrounding lipids which leads to a condensation effect on the membrane bilayer. This affects the dynamics of cholesterol itself which leads to the larger quadrupolar splittings (43). This observation demonstrates that 2 H NMR spectroscopy employing deuterated cholesterol is a sensitive tool for observing very small changes in the behavior of cholesterol.…”

Section: Resultsmentioning

confidence: 77%

“…This could suggest an interaction between cholesterol and tryptophan. However, it was shown before that WALP23 also has a stretching effect (6) is hidden in the central isotropic peak (43,57). on the bilayer similar to that of cholesterol (18) which could cause an increase in quadrupolar splittings.…”

Section: Resultsmentioning

confidence: 99%

“…The 2 H NMR spectrum for a bilayer containing 2 mol % deuterated cholesterol in the absence of peptide (top row in Figure 6) is typical for -(d 6 -2,2,3,4,4,6)cholesterol incorporated into fluid phase bilayers (43). Knowing that the orientation of cholesterol in the bilayer is rather fixed along its long axis, the similarity of the 2 H NMR spectra suggests the same assignment of the splittings to the deuterons in all cases which allows direct comparison of the quadrupolar splittings summarized in Table 2.…”

Section: Resultsmentioning

confidence: 99%

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Is There a Preferential Interaction between Cholesterol and Tryptophan Residues in Membrane Proteins?

et al. 2008

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Recently, several indications have been found that suggest a preferential interaction between cholesterol and tryptophan residues located near the membrane-water interface. The aim of this study was to investigate by direct methods how tryptophan and cholesterol interact with each other and what the possible consequences are for membrane organization. For this purpose, we used cholesterol-containing model membranes of dimyristoylphosphatidylcholine (DMPC) in which a transmembrane model peptide with flanking tryptophans [acetyl-GWW(LA) 8 LWWA-amide], called WALP23, was incorporated to mimic interfacial tryptophans of membrane proteins. These model systems were studied with two complementary methods.(1) Steady-state and time-resolved Förster resonance energy transfer (FRET) experiments employing the fluorescent cholesterol analogue dehydroergosterol (DHE) in combination with a competition experiment with cholesterol were used to obtain information about the distribution of cholesterol in the bilayer in the presence of WALP23. The results were consistent with a random distribution of cholesterol which indicates that cholesterol and interfacial tryptophans are not preferentially located next to each other in these bilayer systems. (2) Solid-state 2 H NMR experiments employing either deuterated cholesterol or indole ring-deuterated WALP23 peptides were performed to study the orientation and dynamics of both molecules. The results showed that the quadrupolar splittings of labeled cholesterol were not affected by an interaction with tryptophan-flanked peptides and, vice versa, that the quadrupolar splittings of labeled indole rings in WALP23 are not significantly influenced by addition of cholesterol to the bilayer. Therefore, both NMR and fluorescence spectroscopy results independently show that, at least in the model systems studied here, there is no evidence for a preferential interaction between cholesterol and tryptophans located at the bilayer interface.

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“…CH was included in all preparations to confer fluidity to the gel-phase membrane (below its transition temperature) and to strengthen liquid crystalphase membrane to prevent a membrane phase transition. 27 DOPC-CH (7:3), DOPC-CH-DOTAP (7:2:1, 7:1:2), DOPC-CH-DOPG (7:2:1), DMPC-CH (7:3), and DPPC-CH (7:3) in liposome preparation gave 3.9%, 17%, 13.6%, 19.2%, 19%, and 17.1% encapsulation efficiency, respectively. DMPC-CH (7:3) was selected for further investigation owing to encapsulation efficiency, concern for stability of protein, and ease of use.…”

Section: Gus Encapsulation In Different Liposome Componentsmentioning

confidence: 98%

Liposomal dry powders as aerosols for pulmonary delivery of proteins

Hickey

2005

AAPS PharmSciTech

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The purpose of this research was to develop liposomal dry powder aerosols for protein delivery. The delivery of stable protein formulations is essential for protein subunit vaccine delivery, which requires local delivery to macrophages in the lungs. β-Glucuronidase (GUS) was used as a model protein to evaluate dry powder liposomes as inhaled delivery vehicles. Dimyristoyl phosphatylcholine:cholesterol (7:3) was selected as the liposome composition. The lyophilization of liposomes, micronization of the powders, aerosolization using a dry powder inhaler (DPI), and in vitro aerodynamic fine particle fraction upon collection in a twinstage liquid impinger were evaluated. After lyophilization and jet-milling, the total amount of GUS and its activity, representing encapsulation efficiency and stability, were evaluated. The GUS amount and activity were measured and compared with freshly-prepared liposomes in the presence of mannitol, 43% of initial GUS amount, 29% of GUS activity after lyophilization and 36% of GUS amount, 22% of activity after micronization were obtained. Emitted doses from dry powder inhaler were 53%, 58%, 66%, and 73% for liposome powder:mannitol carrier ratios of 1:0, 1:4, 1:9, and 1:19. Fifteen percent of the liposome particles were less than 6.4 μm in aerodynamic diameter. The results demonstrate that milled liposome powders containing protein molecules can be aerosolized effectively at a fixed flow rate. Influences of different cryoprotectants on lyophilization of protein liposome formulations are reported. The feasibility of using liposomal dry powder aerosols for protein delivery has been demonstrated but further optimization is required in the context of specific therapeutic proteins.

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Interactions of cholesterol with the membrane lipid matrix. A solid state NMR approach

Cited by 55 publications

References 68 publications

A membrane defect in the pathogenesis of the Smith-Lemli-Opitz syndrome

A membrane defect in the pathogenesis of the Smith-Lemli-Opitz syndrome

Is There a Preferential Interaction between Cholesterol and Tryptophan Residues in Membrane Proteins?

Liposomal dry powders as aerosols for pulmonary delivery of proteins

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