Scavenger receptor, class B, type I-dependent stimulation of cholesterol esterification by high density lipoproteins, low density lipoproteins, and nonlipoprotein cholesterol

Herbert Stangl, Guoqing Cao, Kittie L. Wyne, Helen H. Hobbs

Research output: Contribution to journalArticle

102 Scopus citations

Abstract

Scavenger receptor, class B, type I (SR-BI) is a cell surface glycoprotein that mediates selective uptake and efflux of sterols from high density lipoproteins (HDL) to cells. A Chinese hamster ovary cell line that is deficient in functional LDL receptors, but has high expression levels of recombinant SR-BI (ldlA7-SR-BI), was used to examine the effect of SR-BI on the trafficking of sterols between lipoproteins and cells. To monitor the fate of sterols transported by SR-BI into cells, we measured the incorporation of [14C]oleate into cholesterol esters by acyl- CoA:cholesteryl acyltransferase in the endoplasmic reticulum. We show that incubation of ldlA7-SRBI cells with either LDL or HDL resulted in an equally dramatic increase in the formation of [14C]oleate-labeled cholesterol esters. The lipoprotein-stimulated, SR-BI-dependent increase in cholesterol esterification was inhibited by chloroquine. The uptake of sterols and their incorporation into cholesterol esters by SR-BI from LDL was largely a selective process. The addition of free cholesterol to ldlA7-SRBI cells also stimulated cholesterol ester formation in a chloroquine-sensitive fashion. We also show that SR-BI mediates the efflux of endogenously synthesized sterols from the cell membrane. From these studies we conclude that, in the absence of the LDL receptor, overexpression of SR-BI can mediate significant transport of sterols between lipoproteins and the endoplasmic reticulum of cells.

Original languageEnglish (US)
Pages (from-to)31002-31008
Number of pages7
JournalJournal of Biological Chemistry
Volume273
Issue number47
DOIs
StatePublished - Nov 20 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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