title: Knockdown of hepatic ABCA1 by RNA interference decreases plasma HDL cholesterol levels and influences postprandial lipemia in mice.
abstract: OBJECTIVE
  To investigate the impact of hepatic ABCA1 on systemic lipoprotein metabolism in vivo by an adenovirus-mediated RNA interference approach.
  
  
  RESULTS
  Efficiency of plasmid-based small interference RNA (siRNA)-induced knockdown of cotransfected murine ATP binding cassette transporter A1 (mABCA1) in HEK-293 cells was judged by RT-polymerase chain reaction, immunofluorescence, and Western blot analysis. The most effective plasmid was used to generate a recombinant adenovirus as a tool to selectively downregulate ABCA1 expression in mouse liver (C57BL/6). In comparison to controls, Western blot analysis from liver membrane proteins of Ad-anti-ABCA1 infected mice resulted in an approximately 50% reduction of endogenous ABCA1 and a clear upregulation of apolipoprotein E. Fast protein liquid chromatography analysis of plasma revealed that hepatic ABCA1 protein reduction was associated with an approximately 40% decrease of HDL cholesterol and a reduction of HDL-associated apolipoprotein A-I and E. In the fasted state, other lipoprotein classes were not affected. To analyze the influence of ABCA1 downregulation on postprandial lipemia, infected mice were given a gastric load of radiolabeled trioleate in olive oil. In Ad-anti-ABCA1 infected mice, the postprandial increase of chylomicrons and chylomicron-associated apolipoproteins B and E was significantly reduced as compared with controls.
  
  
  CONCLUSIONS
  Hepatic ABCA1 contributes to HDL plasma levels and influences postprandial lipemia.
authors.affiliation: Institute for Biochemistry and Molecular Biology II, Molecular Cell Biology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Sergei
authors.initials: S
authors.lastname: Ragozin
authors.forename: Andreas
authors.initials: A
authors.lastname: Niemeier
authors.forename: Alexander
authors.initials: A
authors.lastname: Laatsch
authors.forename: Britta
authors.initials: B
authors.lastname: Loeffler
authors.forename: Martin
authors.initials: M
authors.lastname: Merkel
authors.forename: Ulrike
authors.initials: U
authors.lastname: Beisiegel
authors.forename: Joerg
authors.initials: J
authors.lastname: Heeren
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D008076:Cholesterol, HDL / Q000097:blood*; D004041:Dietary Fats / Q000493:pharmacokinetics; D006801:Humans; D006949:Hyperlipidemias / Q000378:metabolism* / Q000503:physiopathology*; D007668:Kidney / Q000166:cytology; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms; D051379:Mice; D008810:Mice, Inbred C57BL; D019518:Postprandial Period; D034622:RNA Interference; D014280:Triglycerides / Q000097:blood
chemical_list: C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D008076:Cholesterol, HDL; D004041:Dietary Fats; D014280:Triglycerides