Characterization of Apolipoprotein-Mediated HDL Generation Induced by cAMP in a Murine Macrophage Cell Line
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- 作者：Sumiko Abe-Dohmae ; Shogo Suzuki ; Youichiro Wada ; Hiroyuki Aburatani ; Dennis E. Vance ; and Shinji Yokoyama
- 刊名：Biochemistry
- 出版年：2000
- 出版时间：September 12, 2000
- 年：2000
- 卷：39
- 期：36
- 页码：11092 - 11099
- 全文大小：106K
- 年卷期：v.39,no.36(September 12, 2000)
- ISSN：1520-4995
文摘
Murine macrophage RAW264 were investigated for their response to lipid-free apolipoproteins.Preincubation of the cells with 300 
M dibutyryl cyclic (dBc) AMP for 16 h induced specific binding ofapolipoprotein (apo) A-I to the cells and apoA-I-mediated HDL formation with cellular lipids, neither ofwhich was detected in the absence of dBcAMP. Dose-dependent changes of the apoA-I specific bindingand the apoA-I-mediated cholesterol release were largely superimposable. ApoA-II also mediated lipidrelease after the treatment of the cells with dBcAMP and effectively displaced the apoA-I binding to thecells. In contrast, cellular cholesterol efflux to lipid microemulsion and to 2-(hydroxypropyl)-
-cyclodextrinwas uninfluenced by the dBcAMP treatment. To induce the cellular reactivity with apoA-I, the incubationwith dBcAMP required at least 6 h. Actinomycin D, cycloheximide, puromycin, and brefeldin A suppressedboth the induction of apoA-I-mediated lipid release and the apoA-I specific binding to the cells. Analysisof the expression level of ABC1 mRNA by using reverse transcription-polymerase chain reaction andoligonucleotide arrays revealed that ABC1 mRNA was already expressed in the dBcAMP-untreated cells,and the dBcAMP treatment for 16 h enhanced its expression 9-13-fold. We conclude that dBcAMPselectively induces apolipoprotein-mediated cellular lipid release and accordingly high-density lipoproteingeneration by inducing specific binding of apolipoprotein, but does not influence diffusion-mediated lipidefflux. The cell-apolipoprotein interaction seems to depend on cellular protein biosynthesis and transport.A substantial increase in the level of ABC1 mRNA caused by the dBcAMP treatment indicates that ATP-binding cassette transporter 1, the protein product of ABC1, may directly be responsible for the interaction,but the question about the absence of the interaction with its baseline expression level remains.
M dibutyryl cyclic (dBc) AMP for 16 h induced specific binding ofapolipoprotein (apo) A-I to the cells and apoA-I-mediated HDL formation with cellular lipids, neither ofwhich was detected in the absence of dBcAMP. Dose-dependent changes of the apoA-I specific bindingand the apoA-I-mediated cholesterol release were largely superimposable. ApoA-II also mediated lipidrelease after the treatment of the cells with dBcAMP and effectively displaced the apoA-I binding to thecells. In contrast, cellular cholesterol efflux to lipid microemulsion and to 2-(hydroxypropyl)--cyclodextrinwas uninfluenced by the dBcAMP treatment. To induce the cellular reactivity with apoA-I, the incubationwith dBcAMP required at least 6 h. Actinomycin D, cycloheximide, puromycin, and brefeldin A suppressedboth the induction of apoA-I-mediated lipid release and the apoA-I specific binding to the cells. Analysisof the expression level of ABC1 mRNA by using reverse transcription-polymerase chain reaction andoligonucleotide arrays revealed that ABC1 mRNA was already expressed in the dBcAMP-untreated cells,and the dBcAMP treatment for 16 h enhanced its expression 9-13-fold. We conclude that dBcAMPselectively induces apolipoprotein-mediated cellular lipid release and accordingly high-density lipoproteingeneration by inducing specific binding of apolipoprotein, but does not influence diffusion-mediated lipidefflux. The cell-apolipoprotein interaction seems to depend on cellular protein biosynthesis and transport.A substantial increase in the level of ABC1 mRNA caused by the dBcAMP treatment indicates that ATP-binding cassette transporter 1, the protein product of ABC1, may directly be responsible for the interaction,but the question about the absence of the interaction with its baseline expression level remains.