title: SR-BI associates with ABCG1 and inhibits ABCG1-mediated cholesterol efflux from cells to high-density lipoprotein 3.
abstract: BACKGROUND
  The single and combined effects of scavenger receptor-BI (SR-BI), ATP-binding cassette transporter (ABC) A1 and G1 on cholesterol efflux from Chinese Hamster Ovary (CHO) cells were investigated.
  
  
  RESULTS
  When apolipoproteinA-I (apoA-I) was used as an acceptor, ABCA1 overexpression led to an increase in total cholesterol (TC) in medium which is attributable to a 2-fold increase in free cholesterol (FC) content. When high-density lipoprotein 3 (HDL3) was used as an acceptor, SR-BI overexpression not only promoted FC efflux, but also promoted the uptake of cholesteryl ester (CE) into cells, resulting in no TC varieties in medium. Overexpression of ABCG1 increased both the FC and CE levels in medium. However, when apoA-I and HDL3 were both used as acceptors, coexpression of SR-BI has no effect on ABCA1-mediated increased FC and TC accumulation in medium. Interestingly, coexpression of SR-BI with ABCG1 blocked the ABCG1-mediated cholesterol efflux to HDL3, mostly by promoting the reuptake of CE from the medium. Furthermore, co-immunoprecipitation experiments revealed that SR-BI interacted with ABCG1 in BHK cells overexpressing ABCG1 and SR-BI.
  
  
  CONCLUSIONS
  We found SR-BI associates with ABCG1 and inhibits ABCG1-mediated cholesterol efflux from cells to HDL3.
authors.affiliation: Key Laboratory of Atherosclerosis in Universities of Shandong, Taishan Medical University, Taian, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Song
authors.forename: Chuanlong
authors.initials: C
authors.lastname: Zong
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Si
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Ping
authors.initials: P
authors.lastname: Zhu
authors.forename: Shucun
authors.initials: S
authors.lastname: Qin
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism; D001693:Biological Transport, Active; D016466:CHO Cells; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D008074:Lipoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D053440:Lipoproteins, HDL3 / Q000378:metabolism*; D051379:Mice; D011994:Recombinant Proteins / Q000378:metabolism; D051122:Scavenger Receptors, Class B / Q000235:genetics / Q000378:metabolism*
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; D016632:Apolipoprotein A-I; D008074:Lipoproteins; D053440:Lipoproteins, HDL3; D011994:Recombinant Proteins; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D002784:Cholesterol