title: Caveolin-1-dependent and -independent membrane domains.
abstract: 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.
authors.affiliation: Centre de Recherche des Cordeliers, INSERM, U872, Université Pierre et Marie Curie, Paris 6, France.
authors.forename: Soazig
authors.initials: S
authors.lastname: Le Lay
authors.forename: Qiong
authors.initials: Q
authors.lastname: Li
authors.forename: Nicholas
authors.initials: N
authors.lastname: Proschogo
authors.forename: Macarena
authors.initials: M
authors.lastname: Rodriguez
authors.forename: Krishanthi
authors.initials: K
authors.lastname: Gunaratnam
authors.forename: Siân
authors.initials: S
authors.lastname: Cartland
authors.forename: Carles
authors.initials: C
authors.lastname: Rentero
authors.forename: Wendy
authors.initials: W
authors.lastname: Jessup
authors.forename: Todd
authors.initials: T
authors.lastname: Mitchell
authors.forename: Katharina
authors.initials: K
authors.lastname: Gaus
mesh_terms: D000818:Animals; D021941:Caveolae; D051242:Caveolin 1 / Q000032:analysis / Q000172:deficiency / Q000502:physiology*; D051243:Caveolin 2 / Q000032:analysis; D021961:Cell Membrane Structures / Q000737:chemistry; D002478:Cells, Cultured; D002784:Cholesterol / Q000032:analysis; D002788:Cholesterol Esters / Q000032:analysis; D002789:Cholesterol Oxidase / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D008297:Male; D021962:Membrane Microdomains / Q000737:chemistry*; D051379:Mice; D018345:Mice, Knockout; D010713:Phosphatidylcholines / Q000032:analysis; D010743:Phospholipids / Q000032:analysis*; D051575:Proto-Oncogene Proteins c-yes / Q000378:metabolism; D013109:Sphingomyelins / Q000032:analysis
chemical_list: D051242:Caveolin 1; D051243:Caveolin 2; D002788:Cholesterol Esters; D005227:Fatty Acids; D010713:Phosphatidylcholines; D010743:Phospholipids; D013109:Sphingomyelins; D002784:Cholesterol; D002789:Cholesterol Oxidase; D051575:Proto-Oncogene Proteins c-yes; C496639:Yes1 protein, mouse