Knockdown of hepatic ABCA1 by RNA interference decreases plasma HDL cholesterol levels and influences postprandial lipemia in mice.
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.
Ragozin
Sergei
S
Institute for Biochemistry and Molecular Biology II, Molecular Cell Biology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
Niemeier
Andreas
A
Laatsch
Alexander
A
Loeffler
Britta
B
Merkel
Martin
M
Beisiegel
Ulrike
U
Heeren
Joerg
J
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
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D008076:Cholesterol, HDL; D004041:Dietary Fats; D014280:Triglycerides