Exposure of bovine pulmonary-arterial endothelial cells to the oxidant lipid t-butyl hydroperoxide (t-Bu-OOH) increases cell-membrane-associated phospholipase A2 (PLA2) activity and stimulates arachidonic acid (AA) release. To test the hypothesis that a membrane-associated serine esterase plays an important role in activating PLA2, the present study was undertaken. In addition to increasing PLA2 activity and AA release, t-Bu-OOH also enhances the activity of a membrane-associated serine esterase that cleaves the synthetic substrate N alpha-p-tosyl-L-arginine methyl ester (TAME). Changes in the activity of this membrane-bound serine esterase correlate directly with changes in the activity of PLA2. Serine esterase inhibitors such as phenylmethanesulphonyl fluoride, di-isopropyl fluorophosphate and alpha 1-proteinase inhibitor, and TAME, a synthetic substrate for serine esterase, prevent the increase in serine esterase activity, PLA2 activity and AA release caused by t-Bu-OOH. Pretreatment of the endothelial cells with the antioxidant vitamin E prevents t-Bu-OOH-induced stimulation of AA release and the cell-membrane-associated serine esterase and PLA2 activities. Adding t-Bu-OOH or the serine esterase trypsin to the endothelial-cell membrane fraction also significantly augments PLA2 activity, implying that these treatments activate latent PLA2. These results suggest that t-Bu-OOH stimulates a membrane-associated serine esterase that plays a crucial role in activating PLA2 and releasing AA.
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June 1993
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Research Article|
June 01 1993
Role of a membrane-associated serine esterase in the oxidant activation of phospholipase A2 by t-butyl hydroperoxide
S Chakraborti;
S Chakraborti
*Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, India
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J R Michael;
J R Michael
†Deparments of Medicine, Salt Lake Veterans Administration Medical Center and the University of Utah Health Science Center, Salt Lake City, UT 84132, U.S.A.
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G H Gurtner;
G H Gurtner
‡Departments of Physiology and Medicine, New York Medical College, Valhalla, NY 10595, U.S.A.
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S S Ghosh;
S S Ghosh
*Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, India
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G Dutta;
G Dutta
*Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, India
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A Merker
A Merker
‡Departments of Physiology and Medicine, New York Medical College, Valhalla, NY 10595, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1993 The Biochemical Society, London
1993
Biochem J (1993) 292 (2): 585–589.
Citation
S Chakraborti, J R Michael, G H Gurtner, S S Ghosh, G Dutta, A Merker; Role of a membrane-associated serine esterase in the oxidant activation of phospholipase A2 by t-butyl hydroperoxide. Biochem J 1 June 1993; 292 (2): 585–589. doi: https://doi.org/10.1042/bj2920585
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