Abstract
ATP-binding cassette transporter A1 (ABCA1) plays an essential role in the helical apolipoprotein-mediated assembly of high density lipoprotein, and the apolipoporteins stabilize ABCA1 against calpain-mediated degradation during the reaction ((2002) J. Biol. Chem. 277, 22426-22429). Protein kinase C (PKC) inhibitors suppressed both ABCA1 stabilization and cellular lipid release mediated by apolipoprotein A-I (apoA-I) but not ABCA1 increase by calpain inhibitors. The increase of ABCA1 and the cellular lipid release by apoA-I were both suppressed by a phosphatidylcholine phospholipase C (PC-PLC) inhibitor but not by the inhibitors of phosphatidylinositol-PLC and phosphatidylinositol 3-kinase. A protein phosphatase inhibitor further enhanced the ABCA1 increase by apoA-I. Biochemical and microscopic evidence indicated that apoA-I activated PKC alpha, and phosphorylation of ABCA1 was directly demonstrated by apoA-I via PKC. Finally, digestion of sphingomyelin increased ABCA1, and a PC-PLC inhibitor suppressed it. We conclude that apoA-I activates PKC alpha by PC-PLC-mediated generation of diacylglycerol initiated by the removal of cellular sphingomyelin ((2002) J. Biol. Chem. 277, 44709-44714), and subsequently phosphorylates and stabilizes ABCA1.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ATP Binding Cassette Transporter 1
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ATP-Binding Cassette Transporters / metabolism*
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Apolipoprotein A-I / metabolism
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Apolipoprotein A-I / physiology*
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Apolipoproteins / metabolism
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Blotting, Western
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Calpain / antagonists & inhibitors
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Cell Line
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Diglycerides / metabolism
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Dose-Response Relationship, Drug
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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Fibroblasts / metabolism
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Green Fluorescent Proteins
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Humans
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Lipid Metabolism
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Lipoproteins, HDL / metabolism*
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Luminescent Proteins / metabolism
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Models, Biological
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Phosphorylation
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Protein Kinase C / antagonists & inhibitors
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Protein Kinase C / metabolism*
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Protein Kinase C-alpha
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RNA, Messenger / metabolism
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Recombinant Fusion Proteins / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
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Signal Transduction
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Sphingomyelins / metabolism
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Time Factors
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Type C Phospholipases / antagonists & inhibitors
Substances
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ABCA1 protein, human
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ATP Binding Cassette Transporter 1
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ATP-Binding Cassette Transporters
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Apolipoprotein A-I
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Apolipoproteins
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Diglycerides
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Enzyme Inhibitors
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Lipoproteins, HDL
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Luminescent Proteins
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RNA, Messenger
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Recombinant Fusion Proteins
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Sphingomyelins
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Green Fluorescent Proteins
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PRKCA protein, human
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Protein Kinase C
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Protein Kinase C-alpha
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Type C Phospholipases
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phosphatidylcholine-specific phospholipase C
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Calpain