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Oxidant-sensitive protein phosphorylation in endothelial cells
A Barchowsky1, M E Williams, C C Benz
1Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH 03755.
Free Radical Biology & Medicine
|June 1, 1994
Summary
Hydrogen peroxide (H2O2) rapidly increases heat shock protein 27 (HSP27) phosphorylation in endothelial cells. This oxidant-induced signaling is independent of protein kinase C (PKC) and calcium.
Area of Science:
- Vascular Cell Biology
- Signal Transduction
- Oxidative Stress
Background:
- Reactive oxygen species (ROS) are critical regulators of vascular cell function.
- Mechanisms of oxidant signal transduction in endothelial cells remain unclear.
- Protein phosphorylation is a key signaling pathway.
Purpose of the Study:
- To investigate oxidant-sensitive changes in endothelial cell phosphorylation.
- To examine the role of protein kinase C (PKC) in H2O2 signaling.
Main Methods:
- Cultured aortic endothelial cells exposed to hydrogen peroxide (H2O2).
- Analysis of heat shock protein 27 (HSP27) phosphorylation.
- Measurement of intracellular free Ca2+ and bradykinin response.
- Assessment using protein kinase C inhibitors and phorbol myristate acetate (PMA).
Main Results:
- H2O2 rapidly increased HSP27 phosphorylation within minutes.
- H2O2 did not alter intracellular Ca2+ levels or bradykinin response.
- H2O2-induced HSP27 phosphorylation was not affected by PKC inhibitors.
- PMA did not induce the same level of HSP27 phosphorylation as H2O2.
- PMA suppressed H2O2-stimulated HSP27 phosphorylation.
Conclusions:
- Endothelial cell responses to H2O2 are mediated by signaling pathways independent of PKC.
- PKC may actively suppress oxidant-induced HSP27 phosphorylation.