title: SR-BI does not require raft/caveola localisation for cholesteryl ester selective uptake in the human adrenal cell line NCI-H295R.
abstract: Class B type I scavenger receptor (SR-BI) mediates the selective uptake of high-density lipoprotein (HDL)-derived cholesteryl esters (HDL-CE) in steroidogenic cells and hepatocytes. SR-BI is enriched in the caveolae of some cell types, genetically modified or not, and these domains have already been shown to constitute primary acceptors for HDL-CE. Nevertheless, the fate of caveola-free cell types has not yet been discussed.NCI-H295R, a human adrenal cell line, highly active in HDL-CE uptake via SR-BI, does not display any morphologically defined caveolae and expresses caveolin at a very low level. Using two different fractionation protocols, we have shown, in this cell type, that SR-BI is homogeneously distributed along the plasma membrane and consists principally of a non-raft membrane-associated pool. Raft destabilisation and caveolin-1 displacement from plasma membrane did not modify the SR-BI-mediated HDL-CE selective uptake. Moreover, the induction of SR-BI expression that is associated with increased CE selective uptake was not associated with any modification in caveolin-1 expression or any raft-targeting mechanism of SR-BI in NCI-H295R. In conclusion, we provide evidence that SR-BI does not require raft/caveola localisation to be implicated in CE selective uptake either in basal or in induced conditions.
authors.affiliation: Inserm UR545, Institut Pasteur de Lille and Faculté des Sciences Pharmaceutiques et Biologiques, Université de Lille 2, 1 rue du Professeur Calmette BP245, 59019, Lille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Briand
authors.forename: Sophie
authors.initials: S
authors.lastname: Lestavel
authors.forename: Antoine
authors.initials: A
authors.lastname: Pilon
authors.forename: Gérard
authors.initials: G
authors.lastname: Torpier
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Fruchart
authors.forename: Véronique
authors.initials: V
authors.lastname: Clavey
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism* / Q000648:ultrastructure; D018955:CD36 Antigens / Q000096:biosynthesis / Q000378:metabolism*; D021941:Caveolae / Q000378:metabolism / Q000648:ultrastructure; D002460:Cell Line; D002788:Cholesterol Esters / Q000378:metabolism*; D005576:Colforsin; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins; D017830:Octoxynol; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B
chemical_list: D018955:CD36 Antigens; D002788:Cholesterol Esters; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C495124:SCARB1 protein, human; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D005576:Colforsin; D017830:Octoxynol