Liver X receptor activation induces the uptake of cholesteryl esters from high density lipoproteins in primary human macrophages.
OBJECTIVE
Liver X receptors (LXRs) are oxysterol-activated nuclear receptors regulating reverse cholesterol transport, in part by modulating cholesterol efflux from macrophages to apoAI and HDL via the ABCA1 and ABCG1/ABCG4 pathways. Moreover, LXR activation increases intracellular cholesterol trafficking via the induction of NPC1 and NPC2 expression. However, implication of LXRs in the selective uptake of cholesteryl esters from lipoproteins in human macrophages has never been reported.


RESULTS
Our results show that (1) selective CE uptake from HDL(3) is highly efficient in human monocyte-derived macrophages; (2) surprisingly, HDL(3)-CE uptake is strongly increased by LXR activation despite antiatherogenic effects of LXRs; (3) HDL(3)-CE uptake increase is not linked to SR-BI expression modulation but it is dependent of proteoglycan interactions; (4) HDL(3)-CE uptake increase is associated with increased expression and secretion of apoE and LPL, two proteins interacting with proteoglycans; (5) HDL(3)-CE uptake increase depends on the integrity of raft domains and is associated with an increased caveolin-1 expression.


CONCLUSIONS
Our study identifies a new role for LXRs in the control of cholesterol homeostasis in human macrophages. LXR activation results in enhanced dynamic intracellular cholesterol fluxes through an increased CE uptake from HDL and leads to an increased cholesterol availability to efflux to apoAI and HDL.
Bultel
Stephanie
S
Institut Pasteur de Lille, Inserm, U545, Université de Lille 2, Faculté de Pharmacie et de Médecine Lille, Lille, France.
Helin
Lionel
L
Clavey
Veronique
V
Chinetti-Gbaguidi
Giulia
G
Rigamonti
Elena
E
Colin
Morvane
M
Fruchart
Jean-Charles
JC
Staels
Bart
B
Lestavel
Sophie
S
D016632:Apolipoprotein A-I / Q000378:metabolism; D050197:Atherosclerosis / Q000209:etiology / Q000378:metabolism; D001693:Biological Transport, Active; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D002788:Cholesterol Esters / Q000378:metabolism*; D008076:Cholesterol, HDL / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000819:agonists / Q000378:metabolism*; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000494:pharmacology; D008075:Lipoproteins, HDL / Q000378:metabolism*; D000071518:Liver X Receptors; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000378:metabolism*; D051122:Scavenger Receptors, Class B / Q000235:genetics / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D005466:Fluorocarbons; D000096926:Benzenesulfonamides
D016632:Apolipoprotein A-I; D051242:Caveolin 1; D002788:Cholesterol Esters; D008076:Cholesterol, HDL; D004268:DNA-Binding Proteins; D006845:Hydrocarbons, Fluorinated; D008075:Lipoproteins, HDL; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D051122:Scavenger Receptors, Class B; D013449:Sulfonamides; C495124:SCARB1 protein, human; C423915:T0901317; D005466:Fluorocarbons; D000096926:Benzenesulfonamides