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J Lipid Res. 2015 Jun;56(6):1123-33. doi: 10.1194/jlr.M057612. Epub 2015 Apr 1.

Micellar lipid composition affects micelle interaction with class B scavenger receptor extracellular loops.

Author information

1
INRA, UMR 1260 "Nutrition, Obesity and Risk of Thrombosis," F-13385 Marseille, France INSERM, UMR 1062, F-13385 Marseille, France Aix-Marseille Université, F-13385 Marseille, France.
2
Aix-Marseille Université CNRS, BIP, UMR 7281, F-13402 Marseille, France.

Abstract

Scavenger receptors (SRs) like cluster determinant 36 (CD36) and SR class B type I (SR-BI) play a debated role in lipid transport across the intestinal brush border membrane. We used surface plasmon resonance to analyze real-time interactions between the extracellular protein loops and various ligands ranging from single lipid molecules to mixed micelles. Micelles mimicking physiological structures were necessary for optimal binding to both the extracellular loop of CD36 (lCD36) and the extracellular loop of SR-BI (lSR-BI). Cholesterol, phospholipid, and fatty acid micellar content significantly modulated micelle binding to and dissociation from the transporters. In particular, high phospholipid micellar concentrations inhibited micelle binding to both receptors (-53.8 and -74.4% binding at 0.32 mM compared with 0.04 mM for lCD36 and lSR-BI, respectively, P < 0.05). The presence of fatty acids was crucial for micelle interactions with both proteins (94.4 and 81.3% binding with oleic acid for lCD36 and lSR-BI, respectively, P < 0.05) and fatty acid type substitution within the micelles was the component that most impacted micelle binding to the transporters. These effects were partly due to subsequent modifications in micellar size and surface electric charge, and could be correlated to micellar vitamin D uptake by Caco-2 cells. Our findings show for the first time that micellar lipid composition and micellar properties are key factors governing micelle interactions with SRs.

KEYWORDS:

cholecalciferol; cholesterol; cluster determinant 36; fatty acid; intestine; phospholipids; scavenger receptor class B type I; surface plasmon resonance

PMID:
25833688
PMCID:
PMC4442870
DOI:
10.1194/jlr.M057612
[Indexed for MEDLINE]
Free PMC Article

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