1-O-hexadecyl-2-O-methyl-sn-glycero-3-phosphocholine inhibits diacylglycerol kinase in WEHI-3B cells.
The effects of 1-O-hexadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET-16-OCH3-GPC) and its metabolite 1-O-hexadecyl-2-O-methyl-sn-glycerol (AMG) on the activity of diacylglycerol kinase (DGK) in WEHI-3B cells were investigated. Treatment of WEHI-3B cells with 200 nM 12-O-tetradecanoylphorbol-13-acetate (TPA) for 5 min leads to the activation of cytosolic DGK without significant effect on microsomal DGK. When these cells were first exposed to 50 microM ET-16-OCH3-GPC for 30 min prior to activation with TPA, the activity of DGK was inhibited by about 70%, as measured by the ability of enzyme to form [32P]phosphatidic acid ([32P]PA). Addition of either ET-16-OCH3-GPC or AMG to the preparation of enzyme in vitro also inhibited 1,2-dioleoyl-sn-glycerol (DG) phosphorylation in the presence of [gamma-32P]ATP. The IC50 value for inhibition of cytosolic DGK by ET-16-OCH3-GPC and AMG were about 8.5 and 15 microM, respectively. ET-16-OCH3-GPC also inhibited the ability of guanosine 5'-O-(3-thiophosphate) (GTP-gamma S) to activate DGK in vitro. The potency of ET-16-OCH3-GPC at 10 microM in inhibiting DGK was greater than that of sphingosine at 50 microM, but less than that of R59022 (a specific DGK inhibitor) at 10 microM.(ABSTRACT TRUNCATED AT 250 WORDS)
Salari
H
H
Department of Medicine, Jack Bell Research Centre, University of British Columbia, Vancouver, Canada.
Low
M
M
Howard
S
S
Edin
G
G
Bittman
R
R
D000818:Animals; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D019852:Diacylglycerol Kinase; D004075:Diglycerides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005995:Glyceryl Ethers / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D051379:Mice; D008861:Microsomes / Q000201:enzymology; D010770:Phosphotransferases / Q000187:drug effects*; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011744:Pyrimidinones / Q000494:pharmacology; D013110:Sphingosine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology
D004075:Diglycerides; D005995:Glyceryl Ethers; D010972:Platelet Activating Factor; D011744:Pyrimidinones; D013844:Thiazoles; C053411:1-O-hexadecyl-2-C-methyl-3-phosphatidylcholine; C059039:1-O-hexadecyl-2-O-methylglycerol; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C047505:R 59022; D010770:Phosphotransferases; D019852:Diacylglycerol Kinase; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate; C013965:diolein