Abstract |
Relationships between phospholipases are poorly understood, but phosphatidic acid (PA) and diglycerides (DGs), produced by phospholipase D ( PLD) and phosphatidate phosphohydrolase actions, might function as second messengers coupling cell stimulation to cellular responses. This study investigates the role of PLD-mediated PA and DG formation in inducing phospholipase A2 (PLA2) activity in intact human neutrophils (PMNs) and in PMNs permeabilized with Staphylococcus aureus alpha-toxin. PMNs were labelled with [3H] arachidonic acid (AA) to assess AA release and metabolism and diacylglycerol formation, or with [3H]1-O-hexadecyl-2-lyso-glycerophosphatidylcholine for the determination of platelet-activating factor ( PAF), PA and alkylacylglycerol production. In intact PMNs primed with tumour necrosis factor alpha before stimulation with N-formyl- Met-Leu-Phe, AA release and metabolism and PAF formation increased in parallel with enhanced PA and DG formation, and inhibition of PA and DG production led to a decrease in both AA release and PAF accumulation. In alpha-toxin-permeabilized PMNs, AA release and PAF production result from the specific activation of cytosolic PLA2 (cPLA2). In this system, PA and DG formation were always present when cPLA2 activation occurred; blocking PA and DG production inhibited AA release and PAF accumulation. Adding either PA or DG back to permeabilized cells (with endogenous PA and DG formation blocked) led to a partial restoration of AA release and PAF formation; a combination of PA and DGs reconstituted full cPLA2 activity. These results strongly suggest that products of PLD participate in activating cPLA2 in PMNs.
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Authors | S A Bauldry, R E Wooten |
Journal | The Biochemical journal
(Biochem J)
Vol. 322 ( Pt 2)
Pg. 353-63
(Mar 01 1997)
ISSN: 0264-6021 [Print] England |
PMID | 9065750
(Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Bacterial Toxins
- Diglycerides
- Hemolysin Proteins
- Phosphatidic Acids
- Platelet Activating Factor
- Tumor Necrosis Factor-alpha
- staphylococcal alpha-toxin
- Arachidonic Acid
- Ethanol
- N-Formylmethionine Leucyl-Phenylalanine
- Phospholipases A
- Phospholipases A2
- Phospholipase D
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Topics |
- Arachidonic Acid
(metabolism)
- Bacterial Toxins
(pharmacology)
- Cell Membrane Permeability
- Cytosol
(enzymology)
- Diglycerides
(biosynthesis, pharmacology)
- Dose-Response Relationship, Drug
- Enzyme Induction
- Ethanol
(pharmacology)
- Hemolysin Proteins
(pharmacology)
- Humans
- N-Formylmethionine Leucyl-Phenylalanine
(pharmacology)
- Neutrophils
(drug effects, enzymology)
- Phosphatidic Acids
(biosynthesis, pharmacology)
- Phospholipase D
(metabolism)
- Phospholipases A
(biosynthesis)
- Phospholipases A2
- Platelet Activating Factor
(metabolism)
- Tumor Necrosis Factor-alpha
(pharmacology)
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