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12,14-Prostaglandin J2 by Augmenting GSH and Activating MAPK
From the Department of Biological Sciences, Allergan, Inc., Irvine, California.
PURPOSE. The goal of this study was to identify the mechanisms by which 15-deoxy-
12,14-prostaglandin J2 (dPGJ2) protects RPE cells from oxidative injury.
METHODS. Cell viability was determined by MTT assay. Protein expression and activation of signaling molecules were detected by Western blot. Reduced glutathione (GSH) was determined by a colorimetric assay kit. PPAR
expression was knockdown by small interfering (si)RNA technique.
RESULTS. dPGJ2 protected ARPE19 cells from oxidative injury, whereas the synthetic PPAR
agonists AGN195037 and rosiglitazone had no effect. PPAR
knockdown also did not affect dPGJ2s protective activity. dPGJ2 upregulated GSH synthesis via induction of glutamylcysteine ligase. GSH depletion sensitized cells to oxidative stress and completely reversed the protective effect of dPGJ2. dPGJ2 activated ERK, JNK, and p38; GSH induction by dPGJ2 depended partially on JNK and p38. In addition, dPGJ2 significantly extended hydrogen peroxideinduced activation of JNK and p38, but not of Akt. Inhibition of MEK, JNK, and p38 abolished dPGJ2s protection of ARPE19 cells from oxidative injury, whereas inhibiting PI3K/Akt pathway failed to affect dPGJ2s protective effect. Heme oxygenase-1 was strongly induced by dPGJ2 but was not associated with protection.
CONCLUSIONS. Independent of its PPAR
activity, dPGJ2 protected cells from oxidative stress by elevating GSH and enhancing MAPK activation. Thus, dPGJ2 may delay the development of dry-type age-related macular degeneration.
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N. G. Abraham and A. Kappas Pharmacological and Clinical Aspects of Heme Oxygenase Pharmacol. Rev., March 1, 2008; 60(1): 79 - 127. [Abstract] [Full Text] [PDF] |
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