Prevention of oxytosis-induced c-Raf down-regulation by (arylthio)cyclopentenone prostaglandins is neuroprotective. (1st September 2017)

• Record Type: Journal Article
• Authors: Shibata, Shoko; Furuta, Kyoji; Oh-hashi, Kentaro; Ueda, Hiroshi; Kiuchi, Kazutoshi; Hirata, Yoko
• Is Part Of: Toxicology. Volume 390(2017)
• Page Start: 83
• Page End: 87
• Publication Date: 2017-09-01
• Subjects: DMEM Dulbecco's modified Eagle medium -- ERK extracellular-regulated protein kinase -- Glu glutamate -- LDH lactate dehydrogenase -- Keap1 Kelch-like ECH-associated protein 1 -- MAPK mitogen-activated protein kinase -- MEK mitogen-activated protein kinase kinase -- NEPPs neurite outgrowth-promoting prostaglandins -- Nrf2 nuclear factor erythroid 2-related factor 2 -- PAGE polyacrylamide gel electrophoresis -- PPARγ peroxisome proliferator-activated receptor-γ -- ROS reactive oxygen species -- SDS sodium dodecyl sulfate; Cyclopentenone prostaglandins -- HT22 cells -- Oxidative stress -- c-Raf; Toxicology -- Periodicals; Chemicals -- Physiological effect -- Periodicals; 615.9005
• DOI: 10.1016/j.tox.2017.09.006
• Languages: English
• ISSNs: 0300-483X

Abstract

Highlights: Down-regulation of c-Raf contributed to glutamate-induced oxytosis. Neuroprotective (arylthio)cyclopentenone prostaglandins preferentially bound to c-Raf. (Arylthio)cyclopentenone prostaglandins prevented down-regulation of c-Raf, resulting in neuroprotection against oxidative stress. Abstract: Prolonged exposure to high concentrations of glutamate leads to cell type specific glutathione depletion and resulting oxidative stress, known as oxytosis. As a result of glutathione depletion, accumulation of reactive oxygen species and Ca 2+ influx are increased; however, the specific target of oxytosis has yet to be identified. In the present study, we focused on the effect of glutamate-induced oxidative stress on the extracellular-regulated protein kinase (ERK) pathway using the murine hippocampal HT22 cell line. Although the contribution of the ERK pathway to glutamate-induced oxytosis in HT22 cells is controversial, Western blot analysis revealed that glutamate caused down-regulation of mitogen-activated protein kinase kinase kinase (c-Raf) and a resulting decrease in the phosphorylation of c-Raf, as well as of mitogen-activated protein kinase kinase1/2 (MEK1/2) and ERK1/2, downstream components of the c-Raf/MEK/ERK pathway. Furthermore, neuroprotective (arylthio)cyclopentenone prostaglandins prevented glutamate-induced c-Raf down-regulation and consequently maintained the basal activity of c-Raf and its downstream signaling components. A pull-down assay using biotin-labeled cyclopentenone prostaglandins revealed that they preferentially bound to c-Raf relative to other signaling molecules of the ERK pathway, including Ras, MEK1/2, and ERK. These results suggest that neuroprotective (arylthio)cyclopentenone prostaglandins directly bind to c-Raf protein and protect cells from down-regulation of the c-Raf protein itself, resulting in neuroprotection against oxidative stress.