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Oxidant-mediated AA release from astrocytes involves cPLA(2) and iPLA(2)
Jianfeng Xu1, Sue Yu, Albert Y Sun
1Department of Biochemistry, University of Missouri, Columbia, MO 65212, USA.
Free Radical Biology & Medicine
|June 6, 2003
Summary
Hydrogen peroxide (H2O2) triggers arachidonic acid (AA) release in astrocytes via both cytosolic phospholipase A2 (cPLA2) and Ca(2+)-independent phospholipase A2 (iPLA2). This study identifies key enzymes involved in oxidative stress-induced neuronal injury.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Reactive oxygen species (ROS) contribute to central nervous system (CNS) injury.
- Oxidants like hydrogen peroxide (H2O2) stimulate arachidonic acid (AA) release in various cells.
- The specific phospholipase A2 (PLA2) enzymes involved in H2O2-induced AA release in astrocytes are not fully understood.
Purpose of the Study:
- To investigate the roles of different PLA2 isoforms in H2O2-mediated AA release from primary murine astrocytes.
- To elucidate the signaling pathways involved in oxidative stress-induced AA release.
Main Methods:
- Primary murine astrocytes were treated with H2O2 or menadione.
- AA release was measured.
- Enzyme activity was inhibited using specific inhibitors (U0126, GF109203x, MAFP, HELSS) and calcium chelation (BAPTA).
- Phosphorylation of ERK1/2 and cPLA2 was assessed.
Main Results:
- H2O2 and menadione dose-dependently stimulated AA release, inhibited by catalase.
- H2O2 induced ERK1/2 and cPLA2 phosphorylation.
- Inhibiting cPLA2 partially reduced AA release, while inhibiting both cPLA2 and iPLA2 nearly abolished it.
- Inhibiting iPLA2 alone or chelating intracellular calcium only partially reduced AA release.
Conclusions:
- Both cytosolic phospholipase A2 (cPLA2) and Ca(2+)-independent phospholipase A2 (iPLA2) are involved in H2O2-mediated AA release in murine astrocytes.
- These findings contribute to understanding the mechanisms of neuronal injury induced by oxidative stress.