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Lipid Free Apolipoprotein E Binds to the Class B Type I Scavenger Receptor I (SR-BI) and Enhances Cholesteryl Ester Uptake from Lipoproteins

2002; Elsevier BV; Volume: 277; Issue: 39 Linguagem: Inglês

10.1074/jbc.m201943200

1083-351X

Stéphanie Bultel-Brienne, Sophie Lestavel, Antoine Pilon, Isabelle Laffont, Anne Tailleux, Jean‐Charles Fruchart, Gérard Siest, Véronique Clavey,

Lipoproteins and Cardiovascular Health

The Class B type I scavenger receptor I (SR-BI) is a physiologically relevant high density lipoprotein (HDL) receptor that can mediate selective cholesteryl ester (CE) uptake by cells. Direct interaction of apolipoprotein E (apoE) with this receptor has never been demonstrated, and its implication in CE uptake is still controversial. By using a human adrenal cell line (NCI-H295R), we have addressed the role of apoE in binding to SR-BI and in selective CE uptake from lipoproteins to cells. This cell line does not secrete apoE and SR-BI is its major HDL-binding protein. We can now provide evidence that 1) free apoE is a ligand for SR-BI, 2) apoE associated to lipids or in lipoproteins does not modulate binding or CE-selective uptake by the SR-BI pathway, and 3) the direct interaction of free apoE to SR-BI leads to an increase in CE uptake from lipoproteins of both low and high densities. We propose that this direct interaction could modify SR-BI structure in cell membranes and potentiate CE uptake.