Abeta[25-35] peptide and iron promote apoptosis in lymphocytes by an oxidative stress mechanism: involvement of H2O2, caspase-3, NF-kappaB, p53 and c-Jun.
The Abeta deposition in the neuritic plaques is one of the major neuropathological hallmarks of the Alzheimer disease (AD). Studies in vitro have demonstrated that the Abeta[25-35] fragment, which contains the cytotoxic functional sequence of the amyloid peptide, induces neurotoxicity and cell death by apoptosis. Despite intense investigations, a complete picture of the precise molecular cascade leading to cell death in a single cellular model is still lacking. In this study, we provide evidence that Abeta[25-35] induce apoptosis either alone or in presence of iron in peripheral blood lymphocytes cells (PBL) in a concentration-dependent fashion by an oxidative stress mechanism involving: (1) the production of hydrogen peroxide (H2O2), reflected by rhodamine-positive fluorescent cells, (2) activation and/or translocation of NF-kappaB, p53 and c-Jun transcription factors showed by immunocytochemical diaminobenzidine positive nuclei, (3) activation of NF-kappaB complex by electrophoretic mobility shift assay/immuno-blotting/and ammonium pyrrolidinedithiocarbamate (PDTC) inhibition, (4) caspase-3 activation, reflected by caspase Ac-DEVD-cho inhibition, (5) mRNA synthesis de novo according to actinomycin D cell death inhibition. These results are consistent with the notion that the Abeta[25-35]/H2O2 generation precede the apoptotic process and that once H2O2 is generated, it is able to trigger a specific cell death signalisation. Thus, taken together these results, we present a well-ordered cascade of the major molecular events leading PBL to apoptosis. These results may contribute to explain the importance of Abeta alone or in the presence of redox-available iron in association with Abeta plaques (and neurofibrillary tangles) in AD brains and the significant role played by H2O2 as a second messenger of death signal in some degenerative diseases linked to oxidative stress stimuli.
Velez-Pardo
Carlos
C
Department of Internal Medicine, School of Medicine, University of Antioquia, Medellin, Colombia. cvelezp@quimbaya.udea.edu.co
Ospina
Gloria Garcia
GG
Jimenez del Rio
Marlene
M
D000328:Adult; D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000235:genetics / Q000502:physiology*; D016923:Cell Death / Q000187:drug effects; D024202:Electrophoretic Mobility Shift Assay; D016758:Genes, jun / Q000235:genetics / Q000502:physiology*; D016158:Genes, p53 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007501:Iron / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D016328:NF-kappa B / Q000235:genetics / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism
D016229:Amyloid beta-Peptides; D016328:NF-kappa B; D010446:Peptide Fragments; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C074636:amyloid beta-protein (25-35); D006861:Hydrogen Peroxide; D007501:Iron; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases