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Papers In Press, published online ahead of print August 1, 2009
J. Lipid Res., doi:10.1194/jlr.M800601-JLR200

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Journal of Lipid Research, Vol. 50, 1609-1620, August 2009
Copyright © 2009 by American Society for Biochemistry and Molecular Biology

Caveolin-1-dependent and -independent membrane domains^[S]

Soazig Le Lay^1,*,, Qiong Li^1,,**, Nicholas Proschogo^,**, Macarena Rodriguez^,**, Krishanthi Gunaratnam^,**, Siân Cartland^,**, Carles Rentero^,**, Wendy Jessup^,**, Todd Mitchell^,**, and Katharina Gaus^2,,**

^* Centre de Recherche des Cordeliers, INSERM, U872, Université Pierre et Marie Curie, Paris 6, France
Université Paris Descartes, Paris F-75006, France
Centre for Vascular Research, University of New South Wales
^** Department of Haematology, Prince of Wales Hospital, Sydney, Australia
School of Health Sciences, University of Wollongong, Wollongong, Australia

² To whom correspondence should be addressed. e-mail: k.gaus{at}unsw.edu.au

Lipid rafts defined as cholesterol- and sphingomyelin-rich domains have been isolated from different cell types that vary greatly in their lipid profiles. Here, we investigated the contribution of the structural protein caveolin-1 (Cav1) to the overall lipid composition and domain abundance in mouse embryonic fibroblasts (MEFs) from wild-type (WT) or Cav1-deficient (Cav1^–/–) animals. Our findings show that Cav1 expression had no effect on free (membrane-associated) cholesterol levels. However, Cav1^–/–-deficient cells did have a higher proportion of sphingomyelin, decreased abundance of unsaturated phospholipids, and a trend toward shorter fatty acid chains in phosphatidylcholine. We isolated detergent-resistant membranes (DRMs), nondetergent raft domains (NDR), and cholesterol oxidase (CO)-sensitive domains and assessed the abundance of ordered domains in intact cells using the fluorescent dye Laurdan. Despite differences in phospholipid composition, we found that cholesterol levels in DRMs, NDR, and CO-sensitive domains were similar in both cell types. The data suggest that Cav1 is not required to target cholesterol to lipid rafts and that CO does not specifically oxidize caveolar cholesterol. In contrast, the abundance of ordered domains in adherent cells is reduced in Cav1^–/– compared with WT MEFs, suggesting that cell architecture is critical in maintaining Cav1-induced lipid rafts.

Supplementary key words lipid rafts • caveolae • lipid profile

Abbreviations: Cav1, caveolin-1; Cav1^–/–, Cav1-deficient; CO, cholesterol oxidase; DRM, detergent-resistant membrane; GP, generalized polarization; GPI, glycosyl phosphatidylinositol; MEFs, mouse embryonic fibroblasts; NDR, nondetergent raft domains; PC, phosphatidylcholine; PL, phospholipids; SM, sphingomyelin; WT, wild type

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