Cloning and expression in Xenopus oocytes of a mouse homologue of the human acylcoenzyme A: cholesterol acyltransferase and its potential role in metabolism of oxidized LDL.
We used a Xenopus oocyte expression system to screen a mouse macrophage cDNA library for receptors for oxidized LDL (OxLDL). Injection of unfractionated mouse macrophage mRNA induced OxLDL binding activity on oocytes. An excess of acetylated LDL (AcLDL) inhibited the binding of OxLDL by only 30%, indicating the expression of OxLDL receptors distinct from the scavenger receptor (SRA). The library was screened and analyzed by competition binding using [125I]OxLDL and AcLDL, to avoid cloning of SRA. One of the purified clones encoded a peptide with 85% identity with human acyl-coenzyme A:cholesterol acyltransferase (ACAT). Injection of ACAT mRNA into oocytes induced specific binding of OxLDL. ACAT is expressed in mouse macrophages as a approximately 3.6 kB transcript and the expression is upregulated in human THP-1 cells treated with PMA.
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Department of Medicine, University of California, San Diego, La Jolla 92093-0682, USA.
Steinberg
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Quehenberger
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D015870:Gene Expression; D006801:Humans; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D002785:Sterol O-Acyltransferase / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014982:Xenopus laevis
D008077:Lipoproteins, LDL; D012333:RNA, Messenger; D002785:Sterol O-Acyltransferase; D013755:Tetradecanoylphorbol Acetate