Cholesterol displacement by ceramide in sphingomyelin-containing liquid-ordered domains, and generation of gel regions in giant lipidic vesicles

Fluorescence confocal microscopy and differential scanning calorimetry are used in combination to study the phase behaviour of bilayers composed of PC:PE:SM:Chol equimolecular mixtures, in the presence or absence of 10 mol% egg ceramide. In the absence of ceramide, separate liquid-ordered and liquid...

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Bibliographic Details
Published in:FEBS letters 2008-09, Vol.582 (21), p.3230-3236
Main Authors: Sot, Jesús, Ibarguren, Maitane, Busto, Jon V., Montes, L.-Ruth, Goñi, Félix M., Alonso, Alicia
Format: Article
Language:English
Subjects:
Calorimetry, Differential Scanning
Ceramide
Ceramides - chemistry
Cholesterol
Cholesterol - chemistry
Differential scanning calorimetry
Fluorescence confocal microscopy
Gels - chemistry
Lipid Bilayers - chemistry
Liposomes - chemistry
Membrane domains
Microscopy, Confocal
Microscopy, Fluorescence
Phosphatidylcholines - chemistry
Phosphatidylethanolamines - chemistry
Sphingomyelin
Sphingomyelins - chemistry
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Summary:Fluorescence confocal microscopy and differential scanning calorimetry are used in combination to study the phase behaviour of bilayers composed of PC:PE:SM:Chol equimolecular mixtures, in the presence or absence of 10 mol% egg ceramide. In the absence of ceramide, separate liquid-ordered and liquid-disordered domains are observed in giant unilamellar vesicles. In the presence of ceramide, gel-like domains appear within the liquid-ordered regions. The melting properties of these gel-like domains resemble those of SM:ceramide binary mixtures, suggesting Chol displacement by ceramide from SM:Chol-rich liquid-ordered regions. Thus three kinds of domains coexist within a single vesicle in the presence of ceramide: gel, liquid-ordered, and liquid-disordered. In contrast, when 10 mol% egg diacylglycerol is added instead of ceramide, homogeneous vesicles, consisting only of liquid-disordered bilayers, are observed.
ISSN:0014-5793
1873-3468
DOI:10.1016/j.febslet.2008.08.016