Prostaglandin E2 synthesis after oxidant stress is dependent on cell glutathione content

Abstract

The role of glutathione in protecting prostaglandin (PG) generation after exposure of fibroblasts to oxidant stress was investigated. Exposure of 3T3 fibroblasts to H2O2, followed by washing and then 20 microM arachidonic acid, caused a dose-dependent decrease in PG synthesis as assessed by radioimmunoassay. PGE2 production decreased from 3.7 +/- 1.1 to 0.15 +/- 0.04 pmol/microgram protein, and prostacyclin (PGI2) formation decreased from 0.56 +/- 0.03 to 0.06 +/- 0.03 pmol/microgram protein after exposure to 200 microM H2O2. Decreasing intracellular glutathione with 50 micrograms/ml 1,3-bis(chloroethyl)-1-nitrosourea (BCNU) enhanced the H2O2-induced decrease in PGE2 synthesis. Another glutathione-depleting agent, 1-chloro-2,4-dinitrobenzene (CDNB), also potentiated the H2O2-induced decrease in PGE2 formation. However, although PGI2 production was decreased by H2O2, neither BCNU nor CDNB potentiated this decrease. Without oxidant stress, extreme glutathione depletion decreased PGE2 synthesis and caused PGI2 synthesis to exceed PGE2. In summary, oxidant stress decreases both PGE2 and PGI2 formation. However, the primary effect of decreasing cell glutathione during oxidant stress is a reduction in PGE2 formation, not PGI2. This implies that the predominant effect of glutathione depletion during oxidant stress is on the PGE2 isomerase(s) and not PGH synthase or PGI2 synthase.

Tumor Necrosis Factor-α Inversely Regulates Prostaglandin D2 and Prostaglandin E2 Production in Murine Macrophages

“…10). Thus, the observed switch from PGD 2 to PGE 2 does not seem to be mediated by depletion of glutathione following TNF␣-induced oxidant stress since both PGE 2 and PGD 2 synthases are glutathione-dependent enzymes (50,51). We next examined whether the observed TNF␣-induced increase in PGE 2 synthase activity was dependent on protein or RNA synthesis.…”

Prostanoid receptors: ontogeny and implications in vascular physiology

“…Neither synthase has greater than 16% sequence identity to any other P-450 enzymes or to each other such that each constitutes its own subfamily, designated CYP8 and CYP5 for PGI 2 synthase and TxA 2 synthase, respectively. Of physiological relevance, because of inherent characteristics and reductive cofactor requirements (GSH and NADPH) for PGI 2 , PGE 2 , PGD 2 , and PGF 2␣ synthases, TxA 2 synthesis is preferentially preserved over that of the other prostanoids during peroxidative processes (3,6,89,182,207,223,227).…”

Evaluation of safety and efficacy of topical prostaglandin E2in treatment of vitiligo

“…Local application of bFGF‐derived peptide alone or in combination with PUVASOL is effective in vitiligo 3 . Oxidative stress, known to cause melanocyte destruction in vitiligo, causes glutathione depletion which in turn decreases PGE 2 isomerase(s) leading to a decrease in PGE 2 4 . PGE 2 is commercially available as a sterile translucent gel preparation containing dinoprostone 0·25 mg g −1 (0·5 mg in 2 g) in a prefilled syringe with a catheter, in a blister pack.…”