title: Transport of lipids from high and low density lipoproteins via scavenger receptor-BI.
abstract: The scavenger receptor-BI (SR-BI) delivers sterols from circulating lipoproteins to tissues, but the relative potency of individual lipoproteins and the transported cholesterol has not been studied in detail. In this study, we used Chinese hamster ovary cells that express recombinant mouse SR-BI but have no functional low density lipoprotein (LDL) receptors (ldlA7-SRBI cells) to compare the fate of lipids transferred from high or low density lipoproteins to cells by SR-BI. HDL and LDL were equally effective in mediating the transfer of [(3)H]cholesterol to cells. Only 5% of the free cholesterol transferred to cells was esterified, in direct contrast to the findings in the cells that express LDL receptors in which 50% of the transported cholesterol was esterified. Almost all the free cholesterol transferred from lipoproteins to cells was rapidly excreted when the ldlA7-SRBI cells were switched to media containing unlabeled lipoproteins. SR-BI expression was associated with an increase in selective cholesteryl ester uptake from both lipoproteins, but HDL was a more effective donor. HDL and LDL were equally effective in delivering cholesterol to the intracellular regulatory pool via SR-BI. These data indicate that SR-BI is able to exchange cholesterol rapidly between lipoproteins and cell membranes and can mediate the uptake of cholesteryl esters from both classes of lipoproteins.
authors.affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
authors.forename: H
authors.initials: H
authors.lastname: Stangl
authors.forename: M
authors.initials: M
authors.lastname: Hyatt
authors.forename: H H
authors.initials: HH
authors.lastname: Hobbs
mesh_terms: D000818:Animals; D018955:CD36 Antigens / Q000378:metabolism*; D016466:CHO Cells; D002460:Cell Line; D002784:Cholesterol / Q000031:analogs & derivatives / Q000378:metabolism; D002788:Cholesterol Esters / Q000378:metabolism; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D050356:Lipid Metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D051782:Sterol Regulatory Element Binding Protein 2; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D018955:CD36 Antigens; D002788:Cholesterol Esters; D004268:DNA-Binding Proteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C497390:SREBF2 protein, human; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D051782:Sterol Regulatory Element Binding Protein 2; D014157:Transcription Factors; C014409:cholesteryl oleate; C023511:cholesteryl oleyl ether; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases