title: Lipopolysaccharide represses the expression of ATP-binding cassette transporter G1 and scavenger receptor class B, type I in murine macrophages.
abstract: OBJECTIVE
  To investigate the regulation of cholesterol transporters, including ATP-binding cassette transporter A1 (ABCA1), ABCG1 and scavenger receptor class B, type I (SR-BI), by inflammatory stimuli in macrophages.                                               MATERIALS AND TREATMENTS:                          RAW 264.7 macrophages and mouse peritoneal macrophages were treated with inflammatory stimuli with or without rosiglitazone, a peroxisome proliferator activated receptor γ (PPARγ) agonist, or T0901317, a liver X receptor (LXR) agonist.
  
  
  METHODS
  Real-time PCR and Western blotting for cholesterol transporters as well as cellular cholesterol efflux to high-density lipoprotein 2 (HDL(2)) were determined.
  
  
  RESULTS
  In RAW 264.7 macrophages, lipopolysaccharide (LPS) significantly reduced ABCG1 and PPARγ as well as cholesterol efflux to HDL(2). Rosiglitazone and T0901317 induced ABCA1 and ABCG1 several-fold, but LPS reduced only ABCG1. ABCG1 and SR-BI proteins, but not ABCA1, were decreased by LPS. In mouse peritoneal macrophages, LPS, tumor necrosis factor α and interleukin-1β decreased ABCG1, SR-BI, LXRα and PPARγ mRNA. The agonists increased ABC transporter expression but LPS reduced mRNA of T0901317-induced ABCA1 as well as basal and agonists-induced ABCG1. SR-BI protein was increased by rosiglitazone but LPS decreased the levels.
  
  
  CONCLUSIONS
  The data suggest that inflammatory insults repress ABCG1 and SR-BI expression partly dependent on PPARγ with a minimal effect on ABCA1 expression.
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Youngki
authors.initials: Y
authors.lastname: Park
authors.forename: Tho X
authors.initials: TX
authors.lastname: Pham
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Lee
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008074:Lipoproteins / Q000235:genetics* / Q000502:physiology; D000071518:Liver X Receptors; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000502:physiology; D057093:Orphan Nuclear Receptors / Q000819:agonists; D047495:PPAR gamma / Q000819:agonists / Q000235:genetics; D051122:Scavenger Receptors, Class B / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics
chemical_list: C487540:ABCG1 protein, mouse; D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D008070:Lipopolysaccharides; D008074:Lipoproteins; D000071518:Liver X Receptors; D016328:NF-kappa B; C000605214:Nr1h3 protein, mouse; D057093:Orphan Nuclear Receptors; D047495:PPAR gamma; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D014157:Transcription Factors; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1