Generation of reactive oxygen species and activation of NF-kappaB by non-Abeta component of Alzheimer's disease amyloid.
Non-amyloid beta (Abeta) component of Alzheimer's disease (AD) amyloid (NAC) coexists with Abeta protein in senile plaques. After exposure to NAC fibrils, cortical neurons of rat brain primary culture became apoptotic, while astrocytes were activated with extension of their processes. NAC fibrils decreased the activity of reducing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) in cortical neurons more markedly (IC(50) = 5.6 microm) than in astrocytes (IC(50) approximately 50 microm). The neuron-specific toxicity of NAC fibrils was indicated also by an increased release of lactate dehydrogenase from the cells. Neuronal apoptosis was suppressed by pre-treatment with the antioxidants, propyl gallate (PG) and N-t-butyl-phenylnitrone (BPN), or overexpression of human Bcl-2. Exposure to NAC fibrils enhanced generation of reactive oxygen species (ROS) in neurons and less efficiently in astrocytes, as demonstrated by oxidation of 2',7'-dichlorofluorescin. The site of ROS generation was shown to be mitochondria by oxidation of chloromethyl-tetramethyl rosamine. Exposure to NAC fibrils increased also the nuclear translocation of nuclear factor kappa B (NF-kappaB) and enhanced its DNA-binding activity, which was inhibited by PG and BPN more efficiently in neurons than in astrocytes. These results suggest that NAC fibrils increase mitochondrial ROS generation and activate NF-kappaB, thereby causing a differential change in gene expression between neurons and astrocytes in the AD brain.
Tanaka
Seigo
S
Laboratory of Molecular Clinical Chemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan. seigo@scl.kyoto-u.ac.jp
Takehashi
Masanori
M
Matoh
Naomi
N
Iida
Shinya
S
Suzuki
Tomoki
T
Futaki
Shiroh
S
Hamada
Hirofumi
H
Masliah
Eliezer
E
Sugiura
Yukio
Y
Ueda
Kunihiro
K
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000544:Alzheimer Disease / Q000378:metabolism*; D000682:Amyloid / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D051843:Synucleins; D013778:Tetrazolium Salts; D013844:Thiazoles
D000682:Amyloid; D000975:Antioxidants; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D051843:Synucleins; D013778:Tetrazolium Salts; D013844:Thiazoles; D004247:DNA; D007770:L-Lactate Dehydrogenase; C022616:thiazolyl blue