Reduction of iron-regulated amyloid precursor protein and beta-amyloid peptide by (-)-epigallocatechin-3-gallate in cell cultures: implications for iron chelation in Alzheimer's disease.
Brain iron dysregulation and its association with amyloid precursor protein (APP) plaque formation are implicated in Alzheimer's disease (AD) pathology and so iron chelation could be considered a rational therapeutic strategy for AD. Here we analyzed the effect of the main polyphenol constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), which possesses metal-chelating and radical-scavenging properties, on the regulation of the iron metabolism-related proteins APP and transferrin receptor (TfR). EGCG exhibited potent iron-chelating activity comparable to that of the prototype iron chelator desferrioxamine, and dose dependently (1-10 microm) increased TfR protein and mRNA levels in human SH-SY5Y neuroblastoma cells. Both the immature and full-length cellular holo-APP were significantly reduced by EGCG, as shown by two-dimensional gel electrophoresis, without altering APP mRNA levels, suggesting a post-transcriptional action. Indeed, EGCG suppressed the translation of a luciferase reporter gene fused to the APP mRNA 5'-untranslated region, encompassing the APP iron-responsive element. The finding that Fe(2)SO(4) reversed the action of EGCG on APP and TfR proteins reinforces the likelihood that these effects are mediated through modulation of the intracellular iron pool. Furthermore, EGCG reduced toxic beta-amyloid peptide generation in Chinese hamster ovary cells overexpressing the APP 'Swedish' mutation. Thus, the natural non-toxic brain-permeable EGCG may provide a potential therapeutic approach for AD and other iron-associated disorders.
Eve Topf and US National Parkinson Foundation Centers for Neurodegenerative diseases and Department of Pharmacology, Faculty of Medicine, Technion, Haifa, Israel.
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Reznichenko
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Amit
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Zheng
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Avramovich-Tirosh
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Youdim
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Weinreb
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Mandel
D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015153:Blotting, Western / Q000379:methods; D016466:CHO Cells; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D003676:Deferoxamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D007501:Iron / Q000502:physiology*; D007502:Iron Chelating Agents / Q000494:pharmacology; D009447:Neuroblastoma; D018696:Neuroprotective Agents / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014162:Transfection / Q000379:methods
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D015703:Antigens, CD; C068126:CD71 antigen; D007502:Iron Chelating Agents; D018696:Neuroprotective Agents; D012333:RNA, Messenger; D011990:Receptors, Transferrin; D002392:Catechin; C045651:epigallocatechin gallate; D007501:Iron; D003676:Deferoxamine