The role of the MAP-kinase superfamily in β-amyloid toxicity
Date
2001
Authors
Daniels W.M.U.
Hendricks J.
Salie R.
Taljaard J.J.F.
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Journal ISSN
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Abstract
The mitogen-activated protein kinase (MAP kinase) pathway participates in a number of reactions of the cell when responding to various external stimuli. These stimuli include growth factor binding to its receptor as well as stressful situations such as hypoxia and oxidative stress. It has been postulated that one of the mechanisms by which β-amyloid exerts its toxic effects is to produce oxidative stress. This study therefore investigated whether the MAP-kinase pathway was activated in cells following exposure to β-amyloid. Neuroblastoma (N2α) cells were used in all experiments. The cells were exposed to 50, 100, and 500 μM glutamate, and 10, 30, and 50 μM β-amyloid, for 24 h. The methylthiazolyl tetrazolium salt (MTT) assay was performed to determine the degree of toxicity. The generation of hydrogen peroxide was detected by fluorescence microscopy using the dye dihydrochlorofluorescein diacetate (DCDHF). Extracellular-signal-regulated kinase (ERK) and p38 MAP-kinase phosphorylation, as representatives of the MAP-kinase pathway, was determined. Treating N2α cells with β-amyloid resulted in a greater than 50% reduction in cell viability. These cells also showed a significantly higher presence of hydrogen peroxide. Western Blot analysis revealed that the phosphorylation of p38 MAP kinase was dose-dependently increased in cells exposed to glutamate and β-amyloid. On the other hand, the phosphorylation of ERK was significantly reduced in these cells. These data therefore suggest that the toxic effects of β-amyloid involve the generation of hydrogen peroxide, leading to the activation of p38 and the down-regulation of ERK.
Description
Keywords
3 (4,5 dimethyl 2 thiazolyl) 2,5 diphenyltetrazolium bromide, amyloid, amyloid beta protein, dihydrochlorofluorescein diacetate, fluorescein, glutamic acid, growth factor, hydrogen peroxide, mitogen activated protein kinase, synaptophysin, tetrazolium, unclassified drug, cell hypoxia, cell viability, conference paper, controlled study, dose response, enzyme activation, enzyme regulation, fluorescence microscopy, hormone receptor interaction, human, human cell, neuroblastoma, neurotoxicity, oxidative stress, protein phosphorylation, receptor binding, stimulus response, Western blotting, Alzheimer Disease, Amyloid beta-Protein, Blotting, Western, Coloring Agents, Dose-Response Relationship, Drug, Hydrogen Peroxide, MAP Kinase Signaling System, Mitogen-Activated Protein Kinases, Neuroblastoma, p38 Mitogen-Activated Protein Kinases, Phosphorylation, Tetrazolium Salts, Thiazoles, Tumor Cells, Cultured
Citation
Metabolic Brain Disease
16
04-Mar
16
04-Mar