Oestradiol-17 beta modulates PAF-evoked phospholipase D activity but not inositide-lipid hydrolysis in human endometrial cell line, HEC-1B.
Platelet-activating factor (PAF) has been shown to stimulate phospholipase D (PLD) activity in human endometrium. The effect of 17 beta-oestradiol on PAF- and 12-O-tetradecanoylphorbol 13-acetate (TPA)-evoked PLD activity assayed as an accumulation of [3H]phosphatidylbutanol was examined in [3H]myristic acid labelled in a human endometrial epithelial cell line HEC-1B. TPA stimulated PLD activity in a dose-dependent manner whereas PAF had no significant effect on PLD activity. Following 48 h pretreatment with 100 nM 17 beta-oestradiol, PAF evoked PLD activity while leaving inositol trisphosphate accumulation in myo-[2-3H] inositol-labelled HEC-1B cells unaffected. In the 17 beta-oestradiol-treated cells, TPA-stimulated PLD activity was significantly elevated at 100 nM TPA (P < 0.05) and 1 microM TPA (P < 0.05) compared to responses in the untreated cells, suggesting that 17 beta-oestradiol may upregulate PKC activity. Interestingly, following a 30 min pretreatment of HEC-1B cells with a range of 17 beta-oestradiol concentrations. TPA (10 nM) and PAF (100 nM) stimulated PLD activity. However, TPA-stimulated PLD activity levels fell 10-fold while PAF-mediated PLD activity remained elevated at 10 nM and 100 nM concentrations of 17 beta-oestradiol suggesting a different mechanism of activation. These results indicate that 17 beta-oestradiol can upregulate PAF-induced PLD activity in HEC-1B cells.
Centre for Clinical Research in Immunology and Signalling, Medical School, University of Birmingham, Edgbaston, UK.
A
A
Ahmed
M A
MA
Shoaibi
R
R
Plevin
S K
SK
Smith
D002273:Carcinogens / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004717:Endometrium / Q000166:cytology / Q000201:enzymology*; D004848:Epithelium / Q000201:enzymology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D015854:Up-Regulation
D002273:Carcinogens; D010716:Phosphatidylinositols; D010972:Platelet Activating Factor; D004958:Estradiol; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate