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Phospholipase D activation in endothelial cells is redox sensitive
N L Parinandi1, W M Scribner, S Vepa
1Department of Medicine, Division of Pulmonary & Critical Care, Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA.
Antioxidants & Redox Signaling
|March 7, 2001
Summary
Reactive oxygen species (ROS) activate phospholipase D (PLD) and protein tyrosine phosphorylation in vascular cells. Exogenous thiol agents like N-acetyl-L-cysteine (NAC) block these ROS-induced effects by modulating cellular thiol-redox status.
Area of Science:
- Endothelial cell biology
- Vascular pathophysiology
- Redox signaling
Background:
- Reactive oxygen species (ROS) play a key role in vascular disorders like atherosclerosis.
- ROS modulate mammalian cell signal transduction pathways.
- Previous studies showed ROS enhance protein tyrosine phosphorylation and phospholipase D (PLD) activation in bovine pulmonary artery endothelial cells (BPAECs).
Purpose of the Study:
- To investigate the role of exogenous thiol agents on ROS-induced PLD activation.
- To examine the influence of cellular thiols (glutathione and protein thiols) on PLD activation and protein tyrosine phosphorylation.
Main Methods:
- Bovine pulmonary artery endothelial cells (BPAECs) were pretreated with various agents.
- Agents included ROS-generating compounds, thiol agents (N-acetyl-L-cysteine, 2-mercaptopropionylglycine), and thiol-depleting agents (diamide, L-buthionine-(S,R)-sulfoximine).
- Measurements included intracellular glutathione (GSH) levels, PLD activity, and protein tyrosine phosphorylation.
Main Results:
- Pretreatment with NAC or MPG blocked ROS-induced changes in intracellular GSH and PLD activation.
- NAC attenuated diperoxovanadate-induced protein tyrosine phosphorylation.
- Diamide or BSO enhanced PLD activity, while NAC blocked these effects and attenuated diamide-induced tyrosine phosphorylation of specific proteins.
Conclusions:
- Modulation of thiol-redox status, encompassing cellular nonprotein and protein thiols, is crucial for regulating ROS-induced protein tyrosine phosphorylation and PLD activation.
- Thiol agents like NAC can counteract ROS-induced signaling in vascular endothelium.
- Findings support a regulatory role for cellular thiols in redox-sensitive signaling pathways within the vascular system.